Plant Health

Spring Showers Bring Flooded Gardens

Posted on May 31, 2025June 2, 2025 by Zidack, Heather

By Amelia Martin, UConn Plant Science Graduate Student

You may have noticed the heavy rains and chilly temperatures last week’s nor ’easter brought to Connecticut. Maybe you were one of many who checked their back window to see their gardens had flooded and their plants are looking worse for the wear. If this sounds familiar and you are curious what garden flooding means for your plants and want to know how to protect them- you found the right article!

A flooded garden is not a unique problem, especially during periods of heavy rainfall, but there are some factors that may contribute to the severity of flooding. Having minimal or poor drainage can amplify the problem, especially if planting in garden boxes with closed bottoms. Soil compaction can contribute to flooding if you are planting directly in the ground. Compacted soil can happen if there has been too much tillage, if wheels or machinery have been over the area, or even from excess foot traffic. Lastly, the layout and landscaping of a yard can contribute to flooding as well. If you placed your garden at the bottom of a hill or there are minimal drainage angles surrounding your garden, water may be pooling up faster than it can drain.

To prevent flooding, check your gutters and make sure they are free from debris and directed to a drain or storm barrel. Put down gravel and mulch to help prevent surface flooding. Avoid cutting your grass too short to maintain strong roots which help to absorb water. Maintain healthy soil to allow for the best water absorption. Dig out a shallow drainage channel if you have the space for it. Consider switching to raised beds with drainage rather than in-ground gardens in easily flooded areas. Try adding native plants to your garden. Native plants have deep roots which helps them absorb excess water and prevent runoff. While handling these issues would be preventative measures, let’s talk about what to do if your garden has already flooded.

Assess the drainage situation and take note of where the water is pooling the most. If flooding is unusual in your garden- there may be something blocking the normal drainage route, which may be a quick fix. If not, knowing where water is likely to pool may help in future garden planning, or help you determine where to make improvements.

Stay off your garden beds. If you step on your soil while it is saturated, it will compact it, ruining the soil’s tilth. Instead, if you need to access your garden beds consider putting a wooden board down to walk on to distribute your weight better.

Re-fertilize your plants. Heavy rain can wash away nutrients out of the soil through a process called leaching. Check the forecast to make sure no more extreme weather is immediately approaching before fertilizing- or you may have to do it again.

Add supports to your plants. The wind and rain may have led to plants falling over. Add in some additional supports to get them upright again and give them a better chance for the next time heavy rain comes.

While having a flooded garden may be a bummer, there are some gardening activities that are actually easier to do in saturated soil! Once the rain stops and the ground is still wet, use this time to weed. The soft ground will make weeds especially easy to pull up- just try not to step on the garden beds. After a rain or a flood, re-mulching is always a good idea. The rain might wash away some previously placed mulch, use this as an opportunity to locate any spots barren of mulch and in need of a re-fill. After a couple days when the soil is soft but not sodden, the ground will be the perfect consistency to dig and put stakes.

Lastly, check for any young plants that didn’t survive the water or any seeds that haven’t come up. Take this as an opportunity to plant new seeds, as seeds do better in already moist soil where they have less chance of being displaced when watered.

At the end of the day, while having a flooded garden may not be the best for your plants, it is not the end of the world. There are a handful of preventative measures that can be taken ranging from backyard renovations to quick fixes- it is about finding what works best for you and your garden.

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at cahnr.uconn.edu/extension/locations.

Spring Landscape and Garden Issues in 2025

Posted on May 10, 2025May 20, 2025 by Zidack, Heather

By Pamm Cooper, UConn Home & Garden Education Center This spring has been a dramatic one as ornamental trees and shrubs are putting on quite a colorful floral display. Many deciduous ornamentals including redbuds, forsythia, crabapples, fruit trees, quince azaleas and many others were not adversely affected by last summer’s drought and the cold, windy winter and frozen soils that followed. A lesser noticed but significant drama is the negative effect these same environmental conditions had on ornamental and native evergreens.

Rhododendrons and ‘Green Giant’ arborvitae seemed to suffer the most damage followed by cherry laurels and hollies. Last year’s drought conditions that extended into late fall combined with very windy winter conditions and frozen soils were tough for some evergreens. Winter desiccation injury on broadleaved and needled evergreens causes foliage browning when plants cannot take up the water needed to keep foliage healthy. Damage to many rhododendrons and some azaleas could be seen during the winter and is still evident this spring. Buds may provide new leaves by June if branches are still alive.

In contrast, 'Green Giant’ arborvitaes suddenly showed symptoms after warm weather began this spring. This was evident especially in trees on windy sites. Needles are brown or off color and time will tell if they are able to recover. If branch tips are flexible and show new buds, growth may resume. Prune any dead branches that show no signs of recovery.

Large tent like structures with little caterpillars inside them in the crotch of a tree branch. — Eastern Tent Caterpillars in a Black Cherry Tree. Photo by Pamm Cooper

Eastern tent caterpillars have hatched from overwintering egg masses on native black cherries. Silken nests are evident located in crotches of these trees. Caterpillars feed outside the tents at night and hide in them during the day. There is only one generation, and feeding is generally finished by late June. Trees have time to leaf out again to remain healthy during the growing season. Birds like cuckoos and vireos will rip tents apart to feed on the caterpillars.

If you have Oriental lilies, be alert for the lily leaf beetle. This bright red insect can severely defoliate these lilies. Adults overwinter in soil close to the plants they were feeding on the previous season. They appear as soon as lilies begin new growth above the ground. Leaf undersides should be checked for eggs and larvae and crushed when found. Leaves can be treated if needed with a product that larvae will ingest as they feed on the treated leaves. Never spray flowers with any insect control product and always follow directions as written on the product label.

Snowball aphid feeding damage is noticeable on the new leaves of European cranberry bush and snowball viburnums. As the aphids feed on the new leaves and twigs, leaves curl and twigs twist in response to aphid feeding on the sap. Aphids can be found by uncurling the leaves. Treatment is difficult as they are not out in the open where contact control products can reach them. Feeding should end within two months of egg hatch. These aphids overwinter as eggs laid on the branches of host viburnums.

Viburnum leaf beetles, Pyrrhalta viburni, are another significant pest of ornamental and native viburnums. They’re active soon after viburnums leaf out. Damage will be seen as larval populations grow and they skeletonize leaves. Some viburnums may suffer complete defoliation. This pest prefers arrowwood, European cranberry bush or American cranberry bush viburnums. Try switching to resistant varieties such as V. plicatum and Korean spicebush viburnum V. calesii if leaf beetles are a chronic pest.

If anyone has small St John’s wort shrubs or certain weigela cultivars that seem to be dead, wait and see if new growth resumes as it gets warmer and sunnier. The smaller St. Johns’ wort shrubs die back in fall, leaving brown stems with withered fruit. Prune these back almost to the ground as basal growth appears. Some weigela cultivars are just slowly getting started, while others are already full of leaves. Do not give up these plants but wait and see what happens in May.

As always, our UConn Home and Garden Education Center office staff welcomes any questions gardeners may have concerning landscape and garden plants problems. Across the New England region, people are having much the same problems as we are having in Connecticut from the winter weather, but we can hope that plant recovery be swift and complete. Enjoy the growing season and stay alert- scout for pests and other problems before they get out of hand.

A Gardener’s Guide to Planting by Hardiness Zones

Posted on May 3, 2025May 20, 2025 by Zidack, Heather

By Marie Woodward, UConn Home & Garden Education Center

Map of Connecticut USDA Hardiness zones as of 2023. Most zones in the state are either zone 6 or zone 7. — USDA Hardiness Zone Map for Connecticut, 2023

If you are wondering whether that shrub, flower, or tree that you saw in a magazine or catalog will grow well in your garden, using a hardiness zone map is your best bet to ensure success.

A hardiness zone map is a tool that divides a geographical area into distinct zones based on average annual minimum winter temperatures. These maps are used by gardeners and farmers around the world to determine which plants are most likely to thrive in a particular region. Each country has its own hardiness map that correlates to their climate. In the United States, the USDA publishes a hardiness zone map, which covers all fifty states and includes Puerto Rico, Guam, American Samoa, and the U.S. Virgin Islands. It uses climate data collected over many years from weather stations throughout a specific region. Then the data is analyzed to determine average minimum winter temperatures from different areas.

The concept of hardiness zones was first introduced in 1927 by Dr. Alfred Rehder. Rehder worked at Harvard's Arnold Arboretum as a botanical taxonomist. He wanted to address the challenges gardeners and growers faced in selecting plants suited to their local climate. Prior to Rehder’s map, there was no standardized system for categorizing plants based on their ability to survive winter temperatures. His hand-drawn map featured eight hardiness zones and was based on the lowest winter temperatures recorded in various regions across the country. Rehder aimed to provide a practical tool for gardeners and growers. His map made it easier for them to choose plants with the best chances of survival in their region, ultimately contributing to more successful gardens and agricultural endeavors. Rehder’s innovative approach recognized the importance of adapting agricultural practices to local climates. In the 1960s, the USDA adopted and adapted Rehder's concept, creating the first official USDA Plant Hardiness Zone Map.

Since its initial release, the USDA Plant Hardiness Zone Map has been updated several times to reflect changes in climate and the availability of more accurate data. The latest update of the USDA hardiness map was released in November 2023, jointly developed by the USDA's Agricultural Research Service (ARS) and Oregon State University's PRISM Climate Group. This update incorporates data from 1991 to 2020, covering a broader range of weather stations than previous versions. One of the key findings from this update is that the contiguous United States has become approximately 2.5 degrees Fahrenheit warmer on average compared to the previous map. As a result, around half of the country has shifted into the next warmer half zone, while the other half has remained unchanged. The updated map still consists of 13 zones, but now offers more detailed information on temperature ranges within each zone, including 10-degree zones and 5-degree half zones. Connecticut has two hardiness zones each of which is divided into half zones; (6a,6b); (7a,7b), to better reflect the temperatures in the state over the past few decades.

The importance of hardiness zones lies in their ability to help gardeners and farmers choose plants that will thrive in their specific region. By selecting plants appropriate for their zone, growers can reduce the risk of frost damage and increase their chances of a successful growing season. However, due to unexpected temperatures outside the average range, there is no guarantee that a plant won’t suffer but it does reduce the risk of plant damage. In addition to gardeners, researchers use hardiness zones to study the spread of insects and exotic weeds, while the USDA Risk Management Agency uses the map to help determine crop insurance rates for commercial growers.

While the USDA Plant Hardiness Zone Map is an invaluable tool, it is important to note that it is not the only factor gardeners and farmers should consider when selecting plants. Other factors, such as soil type, precipitation, and local microclimates, can also impact plant growth and survival. Gardeners should use the map as a starting point and supplement it with local knowledge and research to make the best plant selections for their specific needs.

The development of the USDA Plant Hardiness Zone Map is a testament to the importance of adapting agricultural practices to local climates. Since its inception nearly a century ago, the map has evolved to reflect changes in climate and incorporate more accurate data. Today, the map remains an essential resource for gardeners and researchers alike, helping them to better understand and navigate the complexities of plant growth in the diverse regions of the United States. Knowing a plant’s hardiness zone when selecting that shrub, tree or flower will help you grow the garden of your dreams.

Rocky Start for Rhododendron’s This Spring

Posted on April 12, 2025April 14, 2025 by Zidack, Heather

By Heather Zidack, UConn Home & Garden Education Center

Two Rhododendron shrubs. Shrub in the foreground showing leaf curl while shrub behind it looks healthy and is not displaying any signs of stress. — Rhododendrons are showing a varying degree of stress responses to winter conditions in the landscape. Photo by Heather Zidack

Rhododendrons are looking rough this spring. You’ve probably seen it in your yard or in your neighborhood. The UConn Home & Garden Education Center has been seeing an increase in the number of calls regarding injury or damage to rhododendrons. In most cases, we are finding these reports to be winter injury. This is an environmental type of damage, caused by a perfect storm of conditions that we have seen throughout the state. So, let’s take a closer look into why this is happening.

Plants lose water through their leaves. During active growth, that water is constantly replenished from the roots. When the temperatures drop and the ground freezes in the winter, available water becomes limited. Plants have adapted to this in many ways. Dormancy is triggered by multiple factors, but water conservation is certainly one of those. Deciduous trees shed their leaves completely. Evergreens have developed various leaf adaptations to help with survival, too.

As broadleaf evergreens, rhododendrons have developed a waxy coat on their leaves to help prevent water loss. They also have a physiological mechanism to help defend themselves further. Just as you’d clasp your hands together on a cold winter day to shield them from the elements, rhododendron leaves curl themselves into cigar-shaped cylinders. The leading theory is that this happens to protect the leaves from further water loss. This natural defense mechanism has grabbed our attention this spring, since our weather patterns have lent a hand in amplifying a natural phenomenon.

At the end of last summer, CT started to see a moderate drought in much of the state. These conditions have persisted through this spring. Water availability was limited as plants went into the winter and remained limited throughout the season. Add in frozen soil and harsh winter winds and the environmental stress increased even more. When water is unavailable to the roots – through either freezing or drought conditions, plants lose their ability to return water to the living tissues. This drying out, referred to as desiccation, leads to winter injury or winter kill depending on the severity of damage. While we are finally seeing rain, these plants need time to recover and may not be ready to unfurl just yet.

Many have noted that some plants are faring better than others even within the same bed. This is also normal to some extent. It can be easy to forget that plants are living things in our landscapes. There is going to be variance in their ability to withstand environmental pressures and their recovery rates.

If you are seeing this in your rhododendrons, be patient this spring and monitor over the next month or so. With an increase of rain in the forecast, the extra hydration should help plants recover - or at least push out new growth. These shrubs will shed any leaves that are damaged beyond repair on their own. Do not prune or fertilize shrubs until the end of May to avoid further injury. If we go a week without rain, consider watering your shrubs to help speed up recovery – but only water if the soil feels dry to the touch! If by mid-late May you are seeing absolutely no improvement, we start to consider other factors that may contribute to the plant’s health. For now, they just need a little more time.

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at cahnr.uconn.edu/extension/locations.

Potted Plant Paradise

Posted on March 24, 2025March 28, 2025 by Zidack, Heather

By Dr. Matthew Lisy, UConn Adjunct Faculty
UConn Home & Garden Education Center

Finally, spring is here! It will soon be time to repot all our houseplants as soon as the cold weather completely stops. Many of the plants purchased over the winter, as well as the ones sitting around for years should be repotted. This does not imply that the pot size needs to be increased. Many times, the plant can be left in the same size pot. If it is rootbound, and the plant is known to get large, it’s good to go one pot size up. Increasing the pot size when it is not needed just leads to root rot as the soil will not dry out properly. Alternatively, if the plant is getting big, another option is to divide it into numerous smaller plants, each requiring a smaller pot.

Different varieties of Sansevieria in separate pots — Various Sansevieria species waiting for spring to be repotted – the three in front need bigger pots, and the rear one needs to be split. It’s best to repot during the growing season in order to avoid root rot. (photo by M. Lisy).

Many people think that if the pot size does not need to increase, then there is no need to repot. This could not be further from the truth. The plant is in a fixed medium. The soilless mix will quickly run out of nutrients, even with regular fertilization. Also, salts tend to build up in the soil, which harms the plant over the long run. This is a natural consequence of plants in pots. Soil can also get compacted too much over time and interfere with proper aeration of the root zone. Tease away the loose soil from the root ball being careful not to break the roots. Add the new soil and watch the plant grow!

This is also a great time to change out the pot. Most of our houseplants come in plastic pots. These are usually not very attractive. Plastic pots are good for plants that like to be kept moist. I prefer a clay pot in most cases. This allows the soil to breathe and makes it harder to over water. What I do not care for or recommend are the automatic watering pots. I have found that these have a tendency to keep the soil too moist, and do not allow for a drying out period between waterings. Stores use them as they require no maintenance from their staff, and the plants cannot wither and die due to lack of water. Long term, these types of pots lead to root rot.

Different plants have different soil needs. Cacti and succulents like it dry and fast draining. Orchids like it airy and chunky. Most houseplants prefer a mix that holds moisture but drains. Try and match the plant to the right soil type. There are great commercial mixes available for purchase, and prices on these have come down some lately. Take some time to research the proper soil type for each plant. Many of the plants take a typical houseplant mix, but some require additional drainage. In this case, add perlite and/or sand. To enable to soil to hold moisture for a longer period of time, add some vermiculite.

In all honesty, almost any soil can work for almost any plant provided that the watering is controlled. Most of the time, houseplants get overwatered which leads to fungal problems. People want to water at some magical interval, like every Friday, for example. In reality, the weather greatly influences how quickly or slowly our plants dry out. Sometimes they need water sooner, and sometimes they do not need water at all. Let the plants determine the watering schedule. If all these suggestions are followed, our plants will be living in a potted paradise, as will we!

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at cahnr.uconn.edu/extension/locations.

The Challenges of Boxwood: Pests, Diseases, and Alternatives

Posted on February 22, 2025February 27, 2025 by Zidack, Heather

By Marie Woodward, UConn Home & Garden Education Center

Boxwood, a classic choice for formal gardens and hedges, has faced increasing threats in recent years. As gardeners grapple with these challenges, it is crucial to understand the issues at hand and explore alternative plants for our landscapes.

Boxwood Blight is an aggressive fungal disease that affects various Boxwood species and causes rapid defoliation and potential plant death. First identified in the United Kingdom in the mid-1990s, this disease has since spread across North America. Early symptoms include stem cankers, sunken lesions, and eventual dieback. To mitigate the risk of Boxwood Blight, choose resistant cultivars, practice good garden hygiene, and monitor your plants for early signs of infection.

The Box Tree Moth is an invasive pest native to Asia that feeds on Boxwood plants. Since its arrival in North America, this moth has wreaked havoc on Boxwood populations, leading to defoliation and plant stress. Symptoms of infestation include see-through plants, "stick shrubs," and stem cankers. Regular monitoring and integrated pest management strategies are essential for controlling this destructive insect.

As Boxwood plants continue to face challenges from pests and diseases, it is wise to consider alternative options for our gardens. Ilex crenata (Japanese Holly) is a versatile, broadleaf evergreen that can be shaped into hedges or topiaries. Its small, glossy leaves provide a neat appearance, and its adaptability to various soil types and sun exposure makes it a low-maintenance choice.

Row of Gem Box Ilex shrubs for sale — Gem Box Ilex is one of many fantastic substitutes for Boxwood shrubs. Photo by H. Zidack

Euonymus japonicus (Japanese Euonymus), an evergreen shrub with small, glossy leaves and tolerance for a range of growing conditions is another possible substitution. Its compact growth habit and easy maintenance make it an excellent choice for hedges or screens.

Ilex glabra (Inkberry), is a slow-growing evergreen native to North America, featuring dark green leaves and red berries in the fall. Its low, spreading habit makes it ideal for low hedges or mass plantings.

Privets (Ligustrum), are fast-growing, low-maintenance evergreen shrubs with small, glossy leaves. They can be used for hedges, screens, or as stand-alone specimens. However, keep in mind that three cultivars, border privet, (Ligustrum obtusifolium Sieb. & Zucc), California privet, (Ligustrum ovalifolium Hassk.) and European privet (Ligustrum vulgare L.) are listed on UConn’s invasive plant database. If you decide to plant privets, look for seedless cultivars such as Golden Ticket privet (Ligustrum x vicaryi "KCLX1") at your local nursery.

The Boxwood Blight and Box Tree Moth present ongoing challenges for gardeners and landscapers. By understanding these threats and adopting appropriate management strategies, we can mitigate the damage they cause. Additionally, exploring alternative plants can help create more resilient and sustainable gardens in the face of these challenges. With careful planning and thoughtful plant selection, our landscapes can continue to thrive in the face of adversity.

The UConn Home & Garden Education Center supports UConn Extension’s mission by providing answers you can trust with research-based information and resources. For questions about your boxwoods or other gardening questions, contact us toll-free at (877) 486-6271, visit our website at homegarden.cahnr.uconn.edu, or reach out to your local UConn Extension center at cahnr.uconn.edu/extension/locations.

Helping Plants During the September-October Drought

Posted on October 25, 2024October 23, 2024 by Zidack, Heather

By Pamm Cooper, UConn Home & Garden Education Center

A sloped yard showing signs of drought stress. — Drought stress on a sloped lawn. Photo by Pamm Cooper

Here at the UConn Home and Garden Center we have been getting questions about lawn and garden issues that have been particularly widespread in the state. Whether in the landscape or the garden, there is always something going on, good or bad, and keeping up with pests or cultural issues can be challenging. Because of the extended late season drought conditions this year, plants may be showing signs of stress. There are some basic things homeowners can do to help plants go into winter as healthy as possible.

Plants in temperate climates, like we have in New England, are normally manufacturing food to enable carbohydrate storage for new growth that will occur next spring. To do this, plants need both sunlight and water, and our extended drought conditions have limited most plants to enter survival mode, and carb storage is a second priority. The best way to help your plants is to water deeply any that still have green leaves. People with wells may need to determine if this is a priority for them. We can hope for a warm winter or insulating snow cover to help any plants with shallow roots survive until warm weather returns.

Drought stress on dogwood leaves. Photo by John Ruter

One sign of drought stress in woody broadleaf plants is leaf edges that curl upward. This is a good clue as to the beginning of water stress. Make sure to water these plants deeply, to ensure roots will be able to pick up the water. Usually the next day, leaves will start to uncurl if adequate water is applied. If drought stress continues, leaves may turn brown at the edges and early leaf drop may occur.

Evergreens, even established ones, can benefit from regular watering as long as the soil is not frozen and drought conditions remain. Evergreen foliage, whether needles or leaves, photosynthesize all year, and it is important that soil is not dry. Normally, we have snow that melts on and off, and if soils are not frozen, roots will be able to take up water and photosynthesis can still take place.

Perennials of certain species may be doing fine in this drought. Yarrows, some ox-eyed daisy cultivars, obedient plants, goldenrods, mountain mints and Agastache may be showing no signs of stress. Still, if any have green leaves at this point, consider watering them if dry and warm conditions continue.

This weekend I planted a small shrub, and I had to dig about fourteen inches down to accommodate the root mass. I have to say that I was surprised that the soil, not particularly one that dries out often, was powdery to the bottom of the hole. If you are planting anything now, make sure to water the soil thoroughly as you fill in the area around the roots, then water again when done. This is especially needed for small trees and shrubs but do the same for perennials.

Next year, woody plants that were impacted by drought this year may be more susceptible to certain diseases like verticillium wilt, Nectria canker and evergreens to Rhizosphaera needlecast. Be vigilant and scout for any signs or symptoms of these diseases.

Lawns that did not receive any rainfall or supplemental watering during the past two months may be dormant and crunchy at this time. It may not be clear if the grass will recover when temperatures cool and adequate water is applied. Some grass species may be dead, but it may not be clear until next spring when they fail to green up. There still may be time to apply supplemental irrigation, and with warm temperatures, grass may or may not green up, but at least the crowns may be kept alive to generate new leaves next spring. If any lawn areas were seeded in late summer, water new grass as needed. If it is wilting, water it for sure.

Be alert to what is happening in your own backyard, for the sooner you discover any problems the better. Contact us at the University of Connecticut Home and Garden Education Center for advice on lawns, landscapes, and other gardening subjects. Here's hoping for some needed rainfall and cooler temperatures to help our plants recover from the trying drought of 2024.

Penn State Extension has a good article on long-term effects of drought stress- https://extension.psu.edu/the-long-term-impact-of-drought-on-trees-and-shrubs

If you have questions about caring for plants during a drought, or if you have other gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension center.

Is Early Leaf Drop an Indicator of Tree Health?

Posted on September 27, 2024September 25, 2024 by Zidack, Heather

By Nick Goltz, DPM, UConn Home & Garden Education Center, Plant Diagnostic Lab

Trees showing their autumn colors — Trees showing their fall colors. Photo by Nick Goltz

The autumnal equinox, one of two times of the year at which day and night are equal in length, just passed on Sunday the 22^nd. While this point marks the astrological start of fall, many of the trees lining the roads on my drive to work (and in many of our clients’ yards) seem to want to get a head start on the season. Since late August, we’ve been getting calls from folks across Connecticut asking why the leaves on their trees are changing color and falling early. You may even be thinking, “Hey, a few of my trees are dropping their leaves early too. Is that something that can indicate how healthy they are?” In a word, maybe!

First, let me share the good news that, for most trees, premature color change and leaf drop doesn’t mean that they are in any immediate danger. Plants, much like humans and other animals, respond to stress differently depending on their environment and the kind of year they’ve been having. Just like we might see a little hair loss after a particularly stressful few months, trees may drop their leaves early as a response to stress. Identifying what is causing the stress however, is important when deciding if concern is warranted.

What type of stressors might be causing this early color change and leaf drop? For most trees, the answer is water. Connecticut and several other states in New England had a series of heavy rain events and flash flooding throughout the summer. While we’ve had hardly any rain in the land of steady habits for several weeks now, for many trees, the damage has already been done and symptoms are just appearing now. Saturated soils deprived plant roots of oxygen, damaging them and making them more susceptible to disease. Plants in especially low-lying areas, caught in floodwaters, or grown in poorly-draining clay soils likely experienced the most damage and earliest leaf drop. Some plants may have even perished outright from the damage. Besides water, excessive heat and the increased prevalence of fungal and bacterial diseases, as well as some insect pests, may have also contributed to the stress our plants are letting us know about now.

So, how can you know if the early color change or leaf drop is an issue for your favorite tree or just its way of complaining about a stressful summer? When and where the leaf change and drop is occurring can help you determine if the damage is likely a normal stress response or due to something more sinister.

Consider when the color change and leaf drop first began. In this instance, seeing some leaves begin to change in the last week of August is less concerning than seeing them change at the end of June. Plants that have their leaves change color and drop in midsummer or earlier are most likely dealing with a disease or pest issue, rather than a stress response. I recommend you get advice for these plants by contacting the UConn Home & Garden Education Center and remove them from your garden if they are unlikely to recover.

Also, consider what part(s) of the canopy was affected. Conifers such as white pine drop their leaves (we usually call them needles) in response to stress too, but you will typically see this take place on the interior of the plant – the older needles that aren’t capturing much sun anymore. Branches on deciduous trees, such as oak, that are in shady spots tend to drop their leaves early too, and this is normal.

Branches in full sun that lose their leaves very early, while others on the tree remain fine, are a bit suspicious. Mark these branches with tape or string and monitor them carefully as the plant produces its first leaves or flowers in the spring. If these marked branches do not produce leaves or flowers with the rest of the tree, get advice (again, by contacting the folks at the UConn HGEC)! The best option is usually to cut them close to the main trunk, then disinfect your pruning tools.

If you’re concerned about the health of your tree, including as a result of a potential disease or pest issue, practice good fall habits to give your trees the best foot forward next spring! Clean as much leaf litter as possible and remove it from the base of trees that dropped their leaves early. If you suspect the plant is diseased or has pests, throw away these leaves or burn them before composting. For example, many plant pathogenic fungi can survive the winter on fallen leaves and reinfect healthy plant tissue the following spring. It’s also a good idea to minimize added stress for your plants. Try not to expose them to herbicides, deicing salts, fertilizers, or other chemicals until they’re looking strong again.

If you aren’t sure how to proceed with your fall cleanup or if you’d simply like a second opinion on your favorite tree, get free horticultural consultation from the UConn Home & Garden Education Center by emailing ladybug@uconn.edu or by calling (877) 486-6271.

End of Season Strawberry Renovation

Posted on August 24, 2024September 3, 2024 by Zidack, Heather

By Dawn Pettinelli, UConn Home & Garden Education Center

Strawberry row — Strawberries before renovation at the end of the season. Photos by dmp2024

Strawberry row after renovation — Strawberries after renovation at the end of the season. Photos by dmp2024

So, you decided to grow some strawberries this year. You carefully prepared the bed and have enjoyed your first crop. Now you are wondering what to do to keep your strawberry bed healthy and productive. In part, the care after harvest depends on whether you are growing June bearing or day neutral (everbearing) varieties and what kind of row systems you have them planted in.

June bearing strawberries are most commonly grown in what is known as the matted row system. Mother plants are set 18 to 24 inches apart in 3 to 4 1/2 foot rows and runners are allowed to root anywhere within the row. This system is usually the easiest to maintain. Typically, at the end of the third growing season both plant quality and fruit quantity start to decrease and the whole bed is dug up and replanted with new disease-free strawberry plants. Try to incorporate this into your garden rotation plan to reduce disease problems.

June bearers can also be grown in single rows composed of different aged plants with the original plants set about a foot apart. A second row is started with first year runners and set 18 inches from the initial planting. Use only the first or second daughter plants produced along the runners because they are the most vigorous and productive. The rest are usually discarded.

The next year a third row is made again using the first one or two daughter plants and once more surplus runners and plants are removed. After the original mother plants have produced fruit for about 3 years, they are generally replaced with new, disease-free stock and the cycle continues. This way one always has a row or two of strawberries in production. Ideally the row with the new strawberry plants should be located on a section of the garden where strawberries haven’t been grown for 3 to 5 years. This isn’t always possible in small yards, which is why it is important to purchase certified virus free stock.

After year two when June bearing strawberries have finished producing their crop, it is time to renovate. According to Evan Lentz, UConn Fruit Specialist and Assistant Extension Educator, renovating your June-bearing strawberries is one of the best ways to maximize your annual production, reduce disease instance, and maintain an orderly planting. Proper renovation ensures that you set yourself up for success in the following year and allows you to extend the life and productivity of this semi-perennial crop. This is doubly important for individuals producing fruit in an organic or no-spray system.

This can be done sometime in July through August. Lentz suggests starting by either mowing or clipping with hand trimmers all the foliage about 2 inches or so above the crowns. Next, go through the bed removing all weeds, and weak and extra strawberry plants and dead or dying leaves. Thin to space plants at least 10 to 12 inches apart and cultivate around these remaining plants.

Now is the time to fertilize your strawberries whether beds are renovated or not. Lentz recommends working in about 3 to 4 pounds of 10-10-10 or its organic equivalent per 100 square feet. Lightly scratch the fertilizer into the soil. Brush or rinse any fertilizer off leaves at the salts will injure them.

Day neutrals, such as ‘Tristar’, ‘Seascape’ and ‘Mara des Bois’ produce a fairly decent size crop in June and continue forming occasional berries until frost. Unlike June bearers which develop fruit buds in late summer and early fall, the ever bearers have the ability to form fruit buds throughout the summer. An advantage to growing day neutrals is you will still get strawberries even if a late spring frost kills their initial fruit buds.

In general, day neutrals are grown for 2 or 3 years and then a new batch of strawberries is planted. The day neutrals produce far fewer runners than the June bearers. The new daughter plants should all be removed although they can be transplanted into another area if desired. Plants are usually set one foot apart in single rows about 18 inches wide.

According to Lentz, all strawberries require at least an inch of water per week for vigorous growth. If dry weather sets in, plan on irrigating plants, especially those just renovated. Use a mulch of pine needles, straw or wood shavings to conserve moisture, keep weeds down and berries off the soil. Since strawberries are shallow rooted, it is important to keep weeds under control.

It does take a little time to maintain a strawberry bed but the luxury of picking your own berries for strawberry shortcake, jam or fresh eating makes it all worthwhile. If you have questions about growing strawberries or on any other home or garden topic, contact the UCONN Home & Garden Education Center, toll-free, at (877) 486-6271, visit their web site at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension Center.

Flock to Phlox

Posted on August 9, 2024August 8, 2024 by Zidack, Heather

By Dawn Pettinelli, UConn Home & Garden Education Center

Purple phlox flowers — Purple phlox in bloom. Photo by dmp2024

About now, many of our perennial gardens are looking a bit lackluster. Early summer bloomers have fizzled out and autumn charmers like asters and mums have yet to pop. Garden phlox (P. paniculata) to the rescue!

Annual and perennial phlox comprised about 70 different species, many of which are native to North America. Their habitats range from woodlands to meadow and their growth habits from low and mounded to tall and upright. All have clusters of tubular flowers that are exceptionally attractive to hummingbirds and hummingbird moths along with bees and butterflies.

There are an outstanding number of garden worthy cultivars. My favorite is ‘David’, a white, powdery mildew resistant variety that grows to about 4 feet with loads of slightly fragrant blooms. I have it planted in my white garden and this sturdy, upright plant has come back year after year with virtually no problems.

UConn Plant Science & Landscape Architecture professor, Dr. Jessica Lubell-Brand noted phlox ‘Jeana’, the 2024 Perennial Plant Association’s Perennial Plant of the Year, is treasured for its long blooming period as well as its butterfly luring abilities. Plants can reach up to 5 feet in height and its more loose and wild appearance works well in cottage gardens featuring attractive pink flowers and decent powdery mildew resistance.

Sometimes shorter varieties are a better fit and if that is the case, for your beds look to ‘Coral Crème Drop’, which according to Dr. Lubell are part of the Candy Store series. She raves about their vibrant coral blossoms with their August feel. Another top garden candidate in her book is ‘Glamour Girl’, also with hot coral blooms as well as good resistance to powdery mildew.

A number of garden phlox sport distinctive eyes. ‘Bright Eyes’, as the name implies is a delicate pale pink with a bright crimson eye while ‘Laura’ is a mildew resistant, royal purple variety with a white eye. Both grow to about 3 feet in height.

Many gardeners find these phlox indispensable for August into September color in the perennial garden. They are tough, colorful, vigorous plants that are hardy and relatively long-lived. They make excellent background plants for narrow borders and can bridge the gap between varied sized perennial plantings. Garden phlox come in a wide range of hot and cool colors ranging from white and light pinks, to purples, reds, oranges and magenta.

For healthy, vigorous plants, they should be grown in full sun to part shade. Phlox enjoy a moderately fertile soil with a pH in the 6s. While established plants are fairly drought tolerant, larger and more numerous flower heads are produced when adequate moisture is supplied. They grow at a moderate rate so division every 3 to 4 years is usually sufficient.

Both to encourage sizable blooms as well as to reduce the incidence of phlox’s number one nemesis, powdery mildew, Dr. Lubell recommends reducing the number of stalks early in the growing season to 6 to 8 per plant. This provides better air circulation to plants.

Powdery mildew on phlox leaves. Photo by dmp2024

Powdery mildew is a fungus disease that is more widespread during humid, wet summers. It typically does not kill plants, but they look awful with their leaves covered with what looks like white powder. Two options for dealing with this disease according to Dr. Lubell, are to select resistant phlox cultivars or to pre-emptively spray with a least toxic substance like potassium bicarbonate or your fungicide of choice. As stems die or get killed by frost, be sure to remove them from the garden and put in the trash, not the compost pile.

Insects are not usually a problem but during dry, hot summers, spider mites may attack plants. Usually, a strong blast from the hose will knock them off. This may need to be repeated several times if dry weather persists.

A key gardening practice when growing phlox is dead-heading, or removal of spent flower heads. Garden phlox produce a lot of seeds and if left to fall to the ground and germinate, vigorous plants will most likely produce blooms in that undesirable, muted magenta color. Often these seedlings crowd out the more desirable cultivars that were intentionally purchased.

Not only are garden phlox cultivars pretty spectacular on their own but Dr. Lubell says they pair nicely with a variety of other perennials including lilies, yarrow, ballon flower, daylilies, bee balm as well as numerous annuals.

If you have questions on garden phlox or on any other gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu

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