Gardening

Start Now For a Rosy Summer

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By Dawn Pettinelli, UConn Home & Garden Education Center

A rose shrub in full bloom
Proper care of your roses will give you lots of blooms. Photo by dmp2024

The warmer days of spring will soon be upon us and it is time to think about spring rose care. Any winter protection such as mounded soil, mulch, leaves or rose cones that were placed around grafted bushes should be removed. Release any stems that were tied for winter protection. Fertilize your plants when new growth sprouts with a complete fertilizer such as 5-10-10 or and natural organic equivalent at the rate recommended by a soil test or follow the manufacturer’s instructions on the package. Generally, the fertilizer is sprinkled around the base of the plant and gently worked into the top of the soil.

Repeat blooming roses are heavy feeders and ideally should be fertilized monthly through July. Stop fertilizing at this time as later fertilizations may result in tender new growth late in the season that may not have time to harden off properly. Roses that bloom only once in June are usually only fertilized once in the spring. These include many ramblers and climbers, species roses and antique varieties. Rose books often recommend a dose of Epsom salts for each rose to supply magnesium. If you use a dolomitic limestone to modify the soil pH, however, the plants will most likely have enough magnesium available to them and additional magnesium will not improve growth or branching. Note that according to the American Rose Society, roses prefer slightly acidic soil so strive for a pH between 6.0 and 6.5..

climbing hybrid tea rose ‘Climbing Tangerine.’
This climbing hybrid tea rose is called ‘Climbing Tangerine.’ Photo by dmp2024

Most types of roses benefit from a spring pruning with the exception of climbing roses which are generally pruned immediately following flowering. Roses are pruned to improve their appearance, to remove diseased or dead wood and to increase the quantity and quality of flowers.

Polyanthas, floribundas and shrub roses do not require much pruning. Any canes that are damaged or broken should be removed as well as canes that are rubbing together. If just the tip of the stem is winter killed, cut back to sound wood just above a healthy bud. Rose bushes that are really overgrown can have about one-third of their canes removed from the base.

Hybrid teas and grandifloras usually require more severe pruning. After eliminating all dead and damaged wood, cut back to 18 to 24 inches. Make your pruning cuts at a slant slightly above a bud, preferably one oriented away from the center of the plant.

If your roses are grafted, it is also important to remove any suckers arising from the rootstock.

Spring is a great time to add a few more roses to your garden. Roses are soil either bare-root or as container plants. Those sold in containers can be planted either in partial leaf or full leaf. Mail ordered bare-root stock, however, should be planted when it is still dormant. It is best to plant bare-root roses as soon as you get them. If planting has to be delayed for a day or two, remoisten the packing material and store in a cool, shady location. When it is time to plant bare-root stock, unpack the plant and place the roots in warm water for an hour or two. Cut off any dead or injured parts and plant immediately after soaking.

Roses require a minimum of 6 hours of sun each day for maximum bloom. An area with good air circulation will cut down on disease problems. Soil type is not as important as drainage. Roses will not tolerate wet feet.

When planting grafted plants, set the bud union, which is the point where a rose cultivar is grafted to the root stock, about one inch below the soil level. Roses require about one inch of water per week. If at all possible do not get the leaves wet when watering as this promotes the spread of diseases such as black spot.

Roses benefit from the application of an organic mulch like shredded bark, pine needles or cocoa bean hulls. Mulches not only keep weeds down but help conserve moisture. If you have any questions on roses or other gardening topics, contact the UConn Home & Garden Education at (877) 486-6271 or www.homegarden.cahnr,uconn.edu or your local Cooperative Extension Center.

It’s Spring! Time to Feed the Plants!

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By Dawn Pettinelli, UConn Home & Garden Education Center

Plants need nutrients to grow and develop just like we need vitamins and minerals. They get most of their nutrients dissolved in the water they take up with their roots. When we add fertilizer to the soil around our garden plants, we are adding vital plant nutrients.

Native Connecticut soils are typically low in pH and low in nutrients. Our native plants have adapted to our native soils but most of our garden plants are not from around here. Zinnias and tomatoes are from South America, bluegrass lawns and lilacs hail from Europe and rhododendrons from Asia. Our native soils may not supply the nutrients they need so it is up to us to do so.

Of course, the best way to know which nutrients and how much to add is with a soil test. April is a very busy month at the UConn Soil Nutrient Analysis Lab (www.soiltesting.cahnr.uconn.edu) but there is still time to get your soil tested before planting.

Without soil test recommendations, always follow the directions on the fertilizer package. Applying too much can injure your plants plus excessive nitrogen and phosphorus can wind up in our waterways. Before fertilizing, calculate out the square footage of your garden or lawn. You don’t need to measure exactly; you can measure a pace and then walk down the length and across the width of your gardens to get a rough estimate of area. For odd-shaped beds or lawns, break them down into more square, oval or rectangular areas and add them up.

All fertilizers come with 3 numbers on the package denoting the percent, on a dry weight basis, of nitrogen, phosphorus and potassium. Nitogen promotes green, leafy growth, phosphorus encourages fruits and roots, and potassium is for all round health and tolerance to stresses like drought, cold and disease. So, fertilizers with a higher nitrogen number would be most appropriate for turf grasses, trees and shrubs, while ones higher in phosphorus are generally used in vegetable and flower gardens.

Adding fertilizer to perennials with a watering can and a hand rake.
Fertilizer spread around a perennial. Photo by dmp2024

Whether you select a synthetic or natural organic fertilizer is a matter of personal choice. Both are beneficial to plants. For annual plantings, whether vegetable or flowers, it would be ideal to mix the fertilizer into the top 6 inches of soil. That’s where most of the roots will be so it makes sense that the nutrients they need are there too. Put down the fertilizer, as well as any limestone or other amendments shortly before planting. Long season annuals, like tomatoes, pumpkins and marigolds would appreciate a second application of fertilizer, referred to as side dressing, about 2 months after the first one.

As you are cleaning up your perennial beds and see the new shoots popping through the soil, add some fertilizer around plants and carefully scratch it in. Do the same for bulbs. It is harder to fertilize if the beds are heavily mulched. Not much fertilizer spread on top of mulch will make it to the plant roots. Rake or pull away the mulch, sprinkle some fertilizer directly to the soil around your plants and replace the mulch.

For trees and shrubs, fertilizer should be spread under the whole canopy as a healthy root system will grow at least as wide as the branches and perhaps even more so. Do your best to remove the mulch before fertilizing. Typically trees and shrubs are fertilized once a year in the spring. Once they have reached their mature size, often the fertilizer is cut down to half rate as woody plants can recycle many of the nutrients they need.

Lawns can be fertilized now but pay attention to the moisture level of the soil. With all the rain that we have been experiencing, the soil is pretty soggy in spots. Stay off wet soils as they will become compacted. Most lawns do well with just a spring and fall application of fertilizer. If the clippings are left down, they supply nutrients plus add organic matter to the soil. Be sure to set your spreader on the proper setting.

If you have questions about fertilizing or if you have any other gardening questions, contact the UConn Home & Garden Education at (877) 486-6271 or www.homegarden.cahnr,uconn.edu or your local Cooperative Extension Center.

Watch for Bulb Diseases

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Dr. Nick Goltz, UConn Home & Garden Education Center; UConn Plant Diagnostic Lab

Gardens in New England come to life in spring thanks, in large part, to bulbs! Spring bulbs are reliable, perennial color-bringers and seem equally at home in landscapes and containers. Daffodils (Narcissus spp.), grape hyacinth (Muscari spp.), and tulips (Tulipa spp.), are just some of the bulb plants that grace our gardens this time of year, and they remind us that the blooms of summer alliums aren’t far behind. While these plants might seem effortless to grow, they are not without their fair share of disease issues!

Purple streaking and weak root systems associated with Fusarium rot.
Purple streaking and weak root systems are symptoms associated with Fusarium rot. Ed Kurtz, budwood.org

One common disease of bulbs we see here in Connecticut is Fusarium wilt and bulb rot.

Bulbs generally prefer average to loamy soil with good drainage. When planted in clay soils or following long periods of rain in early spring, however, they are susceptible to rot diseases caused by fungal pathogens such as those in the genus Fusarium. The various wilt and rot diseases caused by Fusarium species can be destructive and sometimes difficult to control. Symptoms include wilting, brown lesions at and below the soil line, vascular discoloration, bulbs that are soft or spongey, and, especially with garlic (Allium sativum) and relatives, a purple-red discoloration of bulb tissue. Plants affected by this soil-borne fungal disease do not recover, so it is wise to be proactive with management and prevention.

If your bulb plants do not emerge properly in the spring or emerge but wilt soon after, fail to flower, or display other symptoms associated with root rot diseases, pull them up and throw them away! Fusarium and similar fungal pathogens often survive the winter in the soil on diseased plant tissue from the year before, so it is important to keep your garden clean and to not compost diseased plant tissue, as most home compost bins do not reach temperatures necessary to kill pathogens. Fungi like Fusarium thrive in soggy soils, so do your best to prevent flooding and standing water where bulbs are planted. There are no fungicides that will completely control or eradicate Fusarium in a landscape, but some are helpful with preventing infection of healthy plants. Remember to always wear protective equipment and follow label rates and instructions if you choose to apply fungicides.

Symptoms of tulip fire, Botrytis tulipae, on tulip flower and leaves.
Symptoms of tulip fire, Botrytis tulipae, include leaf spots on leaves and flowers, often with dark boarders resembling burn injury, lending the common name. Sandra Jensen, Cornell University, Bugwood.org

Another common fungal disease of bulbs grown here in the Northeast is Botrytis gray mold or tulip fire. Fungi in the genus Botrytis cause disease symptoms on many different host plants. Though it is often called “gray mold” when associated with other plants, for tulips, the disease is usually called “tulip fire” due to the spots it causes on leaves and flowers, often with dark borders resembling a burn.

Botrytis fungi are very common and are capable saprophytes, meaning they feed on dead or decaying tissue and contribute to nutrient cycling in the environment, but can be problematic in managed landscapes. To cause disease, Botrytis fungi must first colonize and get nutrients from dead or declining plant tissue, such as fading flower petals, over-ripened fruit. Once the fungus is established in its host plant, it becomes more aggressive and invades healthy plant parts, causing brown lesions and decay.

To prevent Botrytis gray mold and tulip fire, try to encourage good airflow around your plants. Many people plant their bulbs closely together, like eggs in a carton, but this can make bulbs susceptible to tulip fire over time when treated as perennials. Dig up your tulips when they appear crowded, and each year when dealing with a potential disease issue. Inspect bulbs before you plant them again, and discard bulbs that are not firm, discolored, or otherwise do not appear healthy. Rotate to new locations and avoid planting consecutively in the same spot if there has been a history of disease there.

If you have questions about growing bulb plants, are dealing with a plant health issue, or regarding other gardening topics, feel free to contact us, toll-free, at the UConn Home & Garden Education Center by emailing ladybug@uconn.edu. You can also call us at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu, or contact your local Cooperative Extension center.