Perennials

Keep your Perennials & Annuals Looking Fabulous All Season Long!

By: Heather Zidack, UConn Home & Garden Education Center

Geraniums and other flowers in a mixed container
Geraniums benefit from regular deadheading. They’re great for beginners because it is easy to tell the difference between new and spent flowers. Photo by H. Zidack

Hanging baskets, planter boxes and perennial gardens that are bursting with color are seldom planted in spring and left untouched until autumn. Deadheading, pruning, trimming and pinching are all techniques that gardeners can use to get that perfect look all season long. While it may be intimidating, this simple task can result in a huge visual impact with only a little effort. Through a series of pruning techniques, we manipulate our perennials and annuals to give us the most beauty we can get out of them in such a short season. It is important to recognize that cutting healthy flowers or shoots can help plants in the long term – no matter how much it may pain us as gardeners to do so.

Deadheading is a widespread practice where gardeners remove flowers that have gone by. One of the first things to become aware of is the difference between a bud and a spent bloom on the plant you are working on. Many gardeners will snip petunia buds, mistaking them for spent flowers. It is important to be vigilant with these cuts. Remember that your plant's goal is to reproduce, and they use flowers to do so. By removing the flowers, you are stopping the plant from producing seed and encouraging it to restart the cycle – meaning more flowers for you!

Some gardeners will select “self-cleaning” varieties of annuals that will shed their flowers without the need to deadhead all summer long. In general, these may not produce seed; therefore can easily restart the process themselves.

The whole practice of deadheading, pinching and trimming herbaceous plants can be boiled down to redirecting the plants energy into different purposes. Where deadheading helps to clean spent flowers, pinching will remove new buds before they bloom. If you want to encourage beautiful single stem cut flowers, for example, you may decide to pinch lateral (side) flower buds to force the plant to put all its energy into a single bloom at the top. Alternatively, pinching the terminal (top) bud will give you many smaller flowers on one stem, creating a fuller appearance.

This same principle applies to pinching shoots of herbaceous plants to make them fill out more. Cutting further down a stem will again remove that terminal bud and cause the plant to focus its energy on new shoots that come from nodes further down the stem. Think of how full your basil plants flush out when you harvest fresh herbs.

Torenia hanging basket
Torenia is considered a self-cleaning annual that is great for shade and is loved by hummingbirds! Photo by H. Zidack

Often, gardeners will notice that in mid to late summer their hanging baskets will start to look “tired.” They may notice prolific flowering on the ends that hang down, but often see that the center of the basket is not as full or may even be dying out. The first thing to check for is to make sure that you are watering them regularly. Because hanging baskets are suspended in the air and uninsulated, they will dry out faster. When you are trimming herbaceous plants for growth you can take one third of the plant volume away at a time, safely. Think about it as playing hair stylist! Cut back one third of the longest growth at the ends, and watch new growth come from the roots. It may also help your hanging baskets to remove any branches that have been shaded or dried out in the interest of “lightening” the growth that is hanging down.  Again, you may lose flowers for a week or two – but the result down the road will be beautiful!

For perennial gardens, June is a wonderful time to do some pruning as well. Cutting back early flowering perennials can encourage a second flush of flowering in some species. This works exceptionally well for plants like Salvia, Nepeta, and Lavender. Deadheading throughout the season will help plants like roses and Echinacea continuously flower. And pinching can help perennial mums form their shape for the fall.

Summer is a stressful time for plants! Disease, pests, and extreme weather can all contribute to a stressful environment. Our New England summers can promote these pressures with high heat and humidity levels. During these times, pay careful attention to your watering habits and adjust, as necessary. In times of drought or excessive heat, plants will use water faster for hydration and cooling, just like we do. Being aware of this can help you know when to check for water and help you be more diligent with your watering practices. Using a balanced, water-soluble fertilizer can also promote plant health and reduce stress in perennials and annuals. This is why it is great to fertilize after pruning and deadheading. If you need more information on trimming, watering, fertilizing, or 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

Luscious Lemony Herbs

By Dawn Pettinelli, UConn Home & Garden Education Center

With summer almost around the corner, many of us are setting in vegetables and herbs in hopes of preparing delectable culinary delights as these plants mature. Aromatic herbs bring amazing flavors and zing to all sorts of savory and sweet concoctions. A citrusy taste complements many dishes and some may not be aware of the wealth of lemon-flavored herbs that are widely available and also easy to grow.

Lemon balm plants up close.
Lemon Balm in the garden. Photo by dmp2024

Long-lived lemon balm has been a staple in my herb garden for years. The attractive heart-shaped, scalloped leaves have a delicate scent when rubbed. Lemon balm is a hardy perennial native to Europe and has long been grown for its culinary and medicinal purposes. Fresh or dried leaves can be made into a calming tea that reputedly reduces anxiety. They can also be used in savory chicken dishes, to make pesto and even in baked goods. The lemon balm I grow is the species and it produces flowers that, like many members of the mint family, are loved by bees. A dilemma ensues as to whether to leave the blossoms for the pollinators and deal with the copious seedlings that pop up the following year, or cut the plant back to encourage more leaf production. Also, once lemon balm flowers, the leaves take on an unpleasant ‘soapy’ taste. Cultivars such as ‘Compacta’ are sterile, so no seeds are produced.

As long as it is grown in a well-drained soil, lemon thyme is another long-lived herb. Growing just 4 to 6 inches tall, it’s an attractive plant in the herb garden, as an edging plant or even as a front border plant in perennial gardens. There are green, golden, and variegated leaved cultivars. Sprigs of lemon thyme can be dried but I like to use them fresh in chicken or rice dishes. The pinkish flowers usually open in July and are a big pollinator draw. Like many herbs, the best flavor is obtained collected before flowering. Plants respond well to regular trimmings.

Lemon basil is an annual in our climate but easily grown from seed. Like all basils, it does best in a sunny, fertile site with adequate moisture. Plants also do great in containers. Leaves have a fresh lemony scent and taste with some hints of mint and spices. If growing from seed, one might want to try ‘Sweet Dani’, which was a 1998 All America Selection winner. Named cultivars such as ‘Mrs. Burns’ lemon basil usually have larger leaves than the seed grown types. Pinch out flower stalks as they form for better flavor or for a longer and more abundant harvest, cut off the top third of your plants about once a month. This encourages greater branching and leaf production. Lemon basil rice is my favorite way to use fresh leaves.

Lemon grass in a garden bed.
Lemon grass in the garden. Photo by dmp2024

A tender perennial, lemon verbena, is mostly grown as a container plant and overwintered indoors. Plants have an exceptionally strong lemon scent and if happy, grow quite vigorously. They can easily get 3 or 4 feet tall and will grow into a small tree in warmer climates. Lemon verbena is native to South America, so it enjoys full sun and hot weather. Leaves can be used in potpourris, teas, and sweets.

Another tender perennial best grown in a pot is the lemon scented geranium. There are several named cultivars with some, like ‘Mabel Gray’ and ‘Rober’s Lemon Rose’, having a stronger scent. Either buy plants or start from a friend’s cutting. The lovely scented wavy leaves can be placed in the bottom of a cake or loaf pan and then filled with batter and baked, imparting a lovely pattern and slight lemony flavor. They can be used fresh or dried for a variety of culinary uses and are also good in potpourris.

Those enjoying Asian cooking are likely already familiar with the rich flavor of lemon grass. While it is native to India and only hardy to zone 10 to 12, it is a pretty vigorous grower that would do well in either a garden bed or container. Reportedly plants may reach 2 to 3 feet in height by midsummer if kept well-watered. The leaves as well as the bulbous base of

the stem are used in recipes. A few stalks can be removed as needed for cooking. Cut back potted plants to 6 inches before overwintering in a sunny window indoors.

For more information about growing lemon scented herbs or on other gardening topics, 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.

The Do’s and Don’ts of Early Spring Gardening

By Heather Zidack, UConn Home & Garden Education Center 

There’s a well-known scene in the movie “Braveheart” where Mel Gibson’s character, commands his men to “Hold!” as the enemy is rushing upon them. It’s a scene that I often reference as an analogy for this part of the year. Daylight savings time has changed our clocks, the sunshine is warm, temperatures are reaching the “light jacket” level of comfortable, and we all feel spring rushing towards us with the promise of seedlings, flower buds, and fresh green leaves. With this, there are certainly plenty of chores that we can do right now to prepare, but there are others that we really should be waiting for a few weeks longer.  

Houseplants may enjoy a short afternoon in the outdoor sunlight on these warmer days but resist the urge to put them outside full time until night temperatures consistently reach 50 degrees Fahrenheit. The occasional day trip is an effective way to help them transition from the protection of your indoor environment to full sun outdoors. More importantly, consider giving your houseplants a good spring cleaning. Repot or divide root bound plants, remove the winter dust from leaves with a damp rag, and trim out any dead or unsightly growth. Now they’re ready for their spring debut! 

Fertilizing is another task that many gardeners feel may be a chore to check off their lists early. This is a project that should wait a little bit longer. Often, fertilizer will push new growth in your plants. Pushing them too early can leave tender leaves and buds at risk of exposure to frost and freezing temperatures, actively slowing or stunting growth that you intended to give a boost to. In the same vein, grub control, pre-emergent, and many other synthetic materials used in the landscape require specific soil temperatures to be effective and it’s still just too cold. Always read the label of any garden product to learn the best timing of any application. At this point in the year, consider doing a soil test. If you haven’t done so before, it's great to have a baseline for planting and caring for your garden. If you’ve done it a few years ago – check it again! Things change and you may be surprised by what nutrients you need (or don’t) since you last checked in. 

It may still be a little early for mulch as well. Adding fresh mulch too early in the season can trap moisture and slow the soil from warming up to optimum growing temperature. Take this time to pull out grass and weeds that may have taken root in mulched beds and put this time into your hardscape. Look for tripping hazards to address like cracked, sinking, or heaved pavers. Check structures like pergolas, sheds, and even raised beds for rotting boards, warping, or structural damage. Repair as needed. Building new garden spaces is always an option! Create your punch list of projects that will need fresh paint or sealant. If the weather is going to be warm and sunny – consider power washing hardscapes and structures now. 

Newly constructed raised beds
Newly constructed raised beds ready for spring! Photo by HZidack

Late winter/early spring is a fantastic time for pruning trees and shrubs in the landscape. It’s ideal because there is great visibility, and the cooler temperatures prevent disease and insects from taking advantage of fresh wounds. You want to make sure you’re pruning correctly, for the species and purpose of the trees and shrubs in your landscape – so do your homework! As a rule of thumb, roses, hydrangeas, and some hardy perennials tend to appreciate a later pruning and can vary between types within the species, so stay aware of what you have on your property to ensure success!  

“But when do I get to play in the dirt?” That's next! For our outside plants, think about dividing perennials. Divisions at this point in the year make the plants much easier to handle for the gardener. Moving your plants now gives them a chance to “wake up in place” this spring. You will reduce concerns with transplant shock when you move plants ahead of their spring flush and our summer heat. 

Indoors, stepping your seedlings up into larger containers gives them a little more breathing room as we wait for the season to start. Only transplant seeds when they’ve started to show 2-3 sets of true leaves and keep in mind that different species can have different needs. If you excitedly started your tomatoes too early, and now notice leggy stems, try transplanting them in plastic cups and burying them all the way up to their first couple sets of true leaves. They will put out even more roots along that covered stem and be even better prepared when you put them in the garden this season!  

Seedlings transplanted into plastic cups.
Seedlings that are leggy can be moved into plastic cups with holes in them and buried. Photo by H.Zidack 

There are still plenty of projects that can be done while we wait for spring to come! If you have questions on spring garden projects or any other gardening topic, feel free to contact us, toll-free at the UConn Home & Garden Education Center at (877) 486-6247, visit our website at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension Center.