Container Gardening

Firefly Petunias Light Up the Night

By Dr. Matthew Lisy, UConn Adjunct Faculty

A pot of white flowered firefly petunias
Firefly Petunias by Day. (Photo by M. Lissy)

The world of genetics has really had a tremendous impact on our lives. There is a lot of talk about GMOs, or genetically modified organisms, in the news. Labels even alert us to the presence of these crops in our foods. I wanted to share a new plant called the Firefly Petunia. It was not fireflies, but mushrooms that gave this plant its ability to glow. This is known as bioluminescence in the world of biology.

Through feats of genetic engineering, a gene is taken from one organism and placed into another.  This is where people become worried. Humans, however, have been doing this for hundreds of years. The best looking or most productive organisms were bred together for the next generation.  This is called selective breeding, and it essentially concentrates beneficial versions of genes in the offspring.

Now what is determined to be the most beautiful is truly in the eye of the beholder. Some people, for example, selected for white flowers in a normally purple flowered species, Echinacea purpurea. Some have even taken things a step farther and crossed different species of plants to obtain new colors of flowers. In nature, separate species have evolved isolation mechanisms to maintain their identity. When our plant breeders force a cross of the species boundary, much of the time it was done with closely related species of plants within the same genus.  A great example of this is the crossing of Echinacea purpurea, the purple cone flower, with Echinacea paradoxa, the yellow cone flower. This was done to obtain hybrid offspring that have red or orange flowers. These were back crossed with the parent varieties, so they have the same growth habit and form, but with new colored flowers.

Firefly petunia flowers glowing green in the dark.
Firefly petunias by night. This is no trick, the plants actually glow (photo by M. Lisy)

This hybridizing never really ruffled many feathers though, as the plants were very closely related anyway. More modern GMOs, like our Firefly Petunias, are obtained not through “natural” pollination processes, but through genetic manipulation. Scientists literally take one or more genes from one species and place them in another. These species are not closely related, so it may become an ethical conundrum. Here, one may ask if we should take a gene from a mushroom and place it into a plant. A similar circumstance was seen over twenty years ago in the aquarium industry, where genes from corals and jellyfish were placed into tropical fish to make them fluorescent Glofish.

On the question of ethics, I cannot tell you what to think, or what is right or wrong. We each will need to answer that question for ourselves. It does remind me of a quote from Jurassic Park, where Dr. Ian Malcolm states “…your scientists were so preoccupied with whether or not they could that they didn’t stop to think if they should.” The real question is where do we go from here. For the fish, it was species after species of Glofish, and for me, the novelty started wearing off. After all, how many species will be made fluorescent before it just gets boring? Now for our plants, will we have roads lined with glowing trees to eliminate the need for streetlights? Will we have glowing houseplants that function like night lights? Ultimately, it will be up to you, the consumer.

For me, this is just cool science. We ship and plant petunias all over the world. Are these glowing petunias going to cause any harm? Probably not, as none of the other ones have. When I go outside at night to take the dog out and see the bioluminescent petunias, it puts a smile on my face. It reminds me of the fact that we, as humans, are capable of many things. I can’t help but ponder if this will inspire a sense of awe and wonderment in our children. Maybe some may even study genetics because of these petunias. What if one of them ends up finding a cure for a debilitating human disease, all because of a glowing plant? And while some may say that this daydream of mine is just science fiction, need I remind you that so were glowing plants a few years ago?

For your gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at or contact your local Cooperative Extension center.


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

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 or contact your local Cooperative Extension Center.

Grow Vegetables – Save Money

By Dawn Pettinelli, UConn Home & Garden Education Center

Lettuce planted in a container.
This lettuce was planted in a container. Photo by dmp2024

Anyone who grocery shops on a regular basis has likely noticed a higher tally at the checkout counter. The latest consumer pricing analysis from the USDA is predicting a 1.3 percent increase in food prices. While we can’t do much to lower the prices, one thing we can do is grow some of our own vegetables and herbs.

The investment in a small 100 square foot or so garden is not large, and one can be assured of healthy, high quality fresh produce. Vegetable gardeners can also control what, if any, types of pesticides are used on the plants. One source suggested that a $70 investment in plants and seeds could produce a harvest worth $600 or more over the growing season. Already having basic garden tools was probably taken for granted.

If yard space is limited or too shaded, consider renting a plot in a community garden, maybe teaming up with a friend trading garden chores for produce, or consider growing in window boxes and other containers. Even small areas provide opportunities to grow your own food. While a head of lettuce can cost $2-3 dollars at the grocery store, for that same amount one can often pick up a cell-pack of 6 lettuce plants and grow them out in a large container, or 6 square feet or so of garden bed.

Starting plants directly in the garden by direct seeding can also offer considerable savings. I picked up a package of mixed lettuce variety seeds for $3.25 that contains 500 seeds. This would enable one to grow multiple succession plantings for at least 2 or 3 years. If stored in a dark, cool, dry spot, many seeds last for at least 2 years if not longer.

Good candidates for direct sowing would be bush or pole beans, lettuce and other green leafy vegetables, radishes, peas, carrots, summer and winter squash, cucumbers, and corn. If they tickle your tastebuds, you can toss in turnips and parsnips.

Some vegetable varieties have greater cold tolerance than others so your peas, radishes, and many green leafy vegetables can usually be planted by the end of this month depending on the weather. In northern parts of Connecticut, it would be good if the soil warms and dries up a bit more.

Other types of vegetables are better to set in the garden as transplants, whether you grow them yourself or purchase them in cell-packs. The main reason for this is twofold. Certain plants, particularly in the brassica family, like cabbage, broccoli and cauliflower germinate fine in warm household temperatures but like to be grown cooler than many of us keep our houses and if left in those warm temperatures grow long and leggy instead of short and stocky. So, it’s just easier to purchase healthy, stocky plants grown in a greenhouse to set in the garden or container, although the leggy ones usually catch up.

The second reason why some plants are better purchased as transplants is because vegetables like tomatoes, peppers, eggplant and leeks have a long growing season – often 80 to 100 days from transplant until they produce harvestable crops. It makes more sense to plant 3- or 4-week-old transplants around Memorial Day so harvesting can start in late July or August. Contrarily, even though some winter squash and pumpkins might take 100 days or so to mature, I typically just direct seed them around Memorial Day because they seem to catch up with transplants, that usually experience a bit of transplant shock, pretty quickly so I don’t feel like I am gaining much by purchasing transplants and more importantly, the particular varieties I prefer are not always available as plants.

Fresh picked roma style tomatoes
This fabulous roma style tomato is an heirloom variety a friend brought from Italy. It makes a fantastic sauce! Photo by dmp2024

Regardless of whether you have a few containers to fill or a large garden, do some research before purchasing seeds or transplants. There are so many different cultivars available so look up variables like days to harvest, disease resistance, cold tolerance, productivity and more. Make notes on how they taste and any problems during the growing season.

When planning your edible plantings, also think about succession sowings, finding out what pest problems to be on the lookout for, last and first frost dates, mature size and space requirements, and days to harvest.

Feel free to contact the UConn Home & Garden Education Center with questions on growing vegetables, herbs and other plants or if you have any other gardening questions, contact the UConn Home & Garden Education at (877) 486-6271 or www.homegarden.cahnr, or your local Cooperative Extension Center.