Potted herbs include rosmary, thyme, sage and other savory herbs.
For years a gardening ritual of mine has been to tuck my basil and sage in with the cosmos and daylilies in the front garden. The herbs flourished with the annuals and perennials, but I often forgot to harvest their leaves or found myself trampling on their neighbors while trying to reach them.
Lately, I have discovered that growing herbs in containers is actually easier than growing them in the garden. I can just pop out on to the deck through the kitchen door to snip chives for dinner or pluck mint for tea.I don’t have to trample through the mud or worry about the weather. I am also better able to provide the plant what it needs: I can mix up the correct combination of soil moisture and aeration, and I can adjust the light and heat by moving the pots in and out of the shade during the summer.
But what I have enjoyed the most is creating “herbal vignettes.” These mini herb gardens are either groups of pots with a common theme or several herbs in one large container. It is even more fun and creative when you learn the many varieties that are available now through herb nurseries. So far I have experimented with an Asian cuisine herb garden, an Italian cuisine herb garden, a tea garden, and a lemon-scented garden.
Denise Smith, horticulturist with Park Seed Plants suggests that you “start with herbs you use a lot in cooking, if that is your interest, or ones like lavender that are pretty.”
Blooming lemon basil. Photo courtesy Park Seed.
Before you visit your local garden center, first visit a nursery that specializes in herbs or ask for their catalog. Nurseries that specialize in herbs tend to sell a wider range of herbs than garden centers.
“We have over 25 to 30 different basils,” says Francesco DeBaggio, owner of DeBaggio’s Herb Farm and Nursery in Chantilly, Virginia. “We have lots of thyme, lots of varieties of rosemary, and at least a dozen kinds of mints.” Contrary to popular belief, basil is not just a green leafy plant. Some have purple leaves, small leaves, or large floppy leaves. Some even smell like lemons, limes, or cinnamon. Thyme can have orange, lemon, coconut, or a caraway scents; rosemary can smell like mint, chocolate, or orange; and mints have expanded from spearmint and peppermint to chocolate, pineapple, and orange. All of these unusual scents can be used for flavoring in cooking.
“You won’t see the more unusual and interesting herbs at the local garden center or hardware store,” says Chrissy Moore, curator of the National Herb Garden at the US National Arboretum. The National Herb Garden is an eye-opening experience: its extensive collections of rosemary, lavender, scented geraniums, peppers, and salvias are proof of the diversity that exists. If you are not able to visit the National Herb Garden in Washington, DC, contact your local chapter of the Herb Society of America to learn more about herbs or local public herb gardens.
Like any plant, the key to growing herbs successfully in containers is to get to know the herb as a living thing with individual preferences. The four most important characteristics to learn before planting herbs in containers are: 1) their life cycle (annual, biennial, tender perennial, perennial); 2) their preference for soil moisture; 3) their preference for temperature; and 4) their ultimate size. Most will require full sun.
“Dill and cilantro grow quickly, and they are short-lived annuals,” explains DeBaggio. They thrive in moist soil and cool weather and produce leaves for four to six weeks. Afterwards, they will stop producing leaves and start to produce seed. Therefore dill and cilantro will flourish in a large container with other herbs in the spring but by summer they may have to be pulled out. However, by that time, the heat loving herbs may have grown enough to take over the vacant spots. If the dill or cilantro are in their own container you may have an extra empty container on hand in the summer to plant something like basil.
A variety of herbs like these (Salvia tricolor, Capsicum ‘Black Pearl,’ Ipomoea batatas ‘Pink Frost,’ Ocimum ‘Siam Queen,’ Ipomoea batatas ‘Lady Fingers’) can be grouped in one large container. Photo courtesy U.S. National Arboretum.
Basil is a heat loving annual that needs moist soil. Basil will produce a tremendous amount of foliage throughout the summer, but it will turn black at the first hint of frost. The “Mediterranean” herbs: sage, rosemary, thyme, and oregano, like the warmth as well but prefer drier soil.
“Take into consideration the plant’s needs and ultimate size,” says DeBaggio. “For example, you would not want mint and thyme in the same pot because mint can be vigorous and prefers some shade.”Likewise, you would not want to plant a sweet Italian basil and rosemary in one container because the basil will crowd out the rosemary. Basil can grow to be 2 to 21⁄2 feet tall and a foot or so in diameter while rosemary does not grow as fast in the summer.
“Parsley, dill, chives, and cilantro are compatible,” suggests DeBaggio. “Another good combination is rosemary, oregano, thyme, and tarragon because they can tolerate drier conditions.”
If you decide to plant several different varieties in one container, first make sure it is large enough to accommodate the herbs as they grow. Also, notes Smith, “If it is going to be seen from only one side, put the tall plants in the back, mid-size plants in the middle, and smaller and trailing plants on the edges. If you can walk all the way around the pot, put the taller plants in the center and work out from there.”
Any type of container can be used as long as it has drainage holes. In general, small containers will dry out faster than large ones. Also, clay or terra cotta pots will dry out faster than plastic or ceramic/glazed pots because the clay is porous. Therefore, choose the largest containers and the plastic/ceramic ones for herbs that need plenty of moisture. For those herbs that are more drought-tolerant, you can get away with smaller or clay pots. However, probably all containers will have to be watered at least once a week at the peak of summer when the sun shines every day and there is no rain in sight.
When it comes to moisture, like container selection, location is also an important factor. “Just as with a garden,” says Smith, “the more sun and wind the container gets, the more you will have to water. It is much better to really soak the pot every few days than to give it just a little drink every day.”
Instead of using the soil from the garden, buy a bagged, sterilized product, a potting soil, or a soil-less mix. For herbs that prefer drier soil, add perlite to increase air pockets and drainage. Perlite is a naturally occurring siliceous rock that has been heated to expand and pop into small popcorn-like rocks. “At the National Herb Garden, for the most part, we use a good potting soil, not topsoil,” says Moore. “If it does not have perlite, we add some for a two-to-one ratio of soil to perlite to increase drainage.” Francesco uses a commercial soil-less mix for his herbs.
Usually plants that are grown in containers will need fertilizer in the summer because the constant watering and rain washes the nutrients out of the containers. DeBaggio recommends applying a water soluble fertilizer, diluted half strength, once or twice per week in the summer.“We mix in a balanced slow release fertilizer such as Osmocote® and during the summer months we apply a diluted, liquid fertilizer,” says Moore. “A lot of herbs are annuals, so they are in a heavy growth period and you only have a few months to get the most bang for your buck. Fertilizing is even more important if you are harvesting the herbs because you need to replenish the leaves.”
These beautiful herb baskets make herbs like thyme, oregano, golden parsley, peppermint, and spearmint easily accessible for use in your everyday cooking. Photo courtesy provenwinners.com.
Harvesting is the fun part. By grouping herbs by their use or by species, you can quickly harvest what you need from one location. “I grow five to seven mints in separate plastic pots,” says Pat Kenny, long time member of the Potomac Unit chapter of the Herb Society of America. “I use the mints for teas, syrups, and potpourris.”
Because mint can be very invasive, Smith suggests that is it is perfectly suited to growing in containers. However, she says, “Set the pot on a patio, or raise it on a plant stand. If the drainage holes touch the ground, the mint will escape and spread!”
If you tend to cook Italian meals, you can plant marjoram, oregano, rosemary, and thyme in a large container, surrounded by separate pots of basil and parsley. A trio of pots-cilantro, hot peppers, and lemon grass-can complement Asian dishes. Or grow herbs that can be used to make tea: a large container with a variety of mints, a separate pot of chamomile, and maybe a pot of pineapple mint.
A fun summer project is to plant many cultivars of one herb in order to learn more about that plant. “When calendula was Herb of the Year for 2008, I had 18 different calendulas in separate pots,” says Kenny. “Some grew to be leggy and some more compact. Many of the flowers were different versions of yellow and orange. When they became pot-bound (root-bound), I moved them around on the deck to give them more shade so they would not frazzle in the sun.”
Growing herbs in containers gives you much more flexibility. Not only does it make it easier to grow and harvest, but you can learn more by grouping similar plants into mini herb gardens.
Peggy Riccio is a Contributing Editor for ChesapeakeHome.
Contacts:
DeBaggio’s Herb Farm and Nursery: debaggioherbs.com or 703-327-6976
Herb Society of America: herbsociety.org or 440-256-0514
National Herb Garden at the US National Arboretum: usna.usda.gov or 202-245-2726
Park Seed Company: parkseed.com or 800-213-0076
