Tidewater Gardening - December 2012

Holiday Herbs and Plants
K. Marc Teffeau

With most of our outdoor gardening activities completed for the year, our interests turn to being inside and the plant “opportunities” that the gardener might have indoors. Have you considered an indoor herb garden? A couple of herbs that were in your outside herb garden can be kept indoors for use in the kitchen for the winter.
For example, if you grew lavender (Lavandula angustifolia) in the flower garden this past summer, you may be enjoying the sweet scents of dried bouquets right now. Fragrance is not the only nice feature of this flower, however, as it is also used for color in potpourri. Some people occasionally use it sparingly to flavor teas and meats.
Lavender is a perennial that traditionally will not bloom the first year from seed. There is one variety, however, Lady English Lavender, that can be grown from seed and will consistently flower the first year.
Tender lavender varieties do best in winter window gardens and they perform well in pots placed near sunny windows. Use a well drained potting media such as peat moss and perlite in equal amounts with one tablespoon of lime added per 6 inches of pot. Lavender cannot tolerate acidity below pH 6.5 or above pH 8.5.
Allow the soil to dry between waterings so the roots of the lavender do not rot. During the winter, fertilize monthly with a weak solution of a liquid houseplant fertilizer. Overcrowded roots can cause potted herbs to turn brown on the leaf tips. If you see these signs, replant in a pot one or two sizes larger.
Rosemary is another herb that can be grown indoors during the winter. This herb has a long holiday tradition in Europe where it is used as a Christmas evergreen. Topiary rosemary in the form of a wreath or a tree is an excellent holiday plant to give or receive. They require a little extra care to maintain their shape and health. Leave the supporting wires for the wreath or topiary in place. For a standard form with single, bare stems, you occasionally will have to loosen the ties that hold the stem to its support. The stem will not change in height but will increase in diameter.
Both the head of the standard and the body of the wreath need to be shaped periodically, so clip new growth for cooking or drying. Clipping will enhance branching, and you’ll have a fuller topiary.
Rosemary does best in a sunny, southern window. Allow this plant to dry between waterings almost to the point of wilting. It is very sensitive to excess watering. If leaf tips or whole leaves turn brown and fall off, the plant has too much water. Rosemary does not require high humidity, either.
A discussion about holiday plants is missing a major player if we don’t mention poinsettias. The poinsettia is our most popular Christmas flower today. Plant breeders have developed a number of different colors to add to the traditional red. White, pink, white/pink combinations, salmon and even a yellow poinsettia are available.
The success and popularity of the poinsettia as a holiday flower wasn’t always the case. The poinsettia isn’t, as some believe, a native of the Holy Land, but instead grows wild as a shrub in Central America up through Florida. It was introduced into the United States in 1825 by Joel Robert Poinsett, our first ambassador to Mexico. The name “poinsettia” is in his honor.
The poinsettia was first propagated and sold in this country by Robert Buist, one of Philadelphia’s early nurserymen. By the late 1800s the plants were being grown by florists for Christmas, but they were still somewhat a rarity at the turn of the century.
The early poinsettias were “contrary” plants and difficult to grow. Any change in the environment and they dropped their leaves. In fact, florists used to plant ferns with them so that when the leaves fell off the poinsettias their stems wouldn’t look so bare.
The first improvement in the florist’s poinsettia was the variety called “Oakleaf,” reported to have been developed in New Jersey in 1923. Development of this exotic plant has continued and today’s poinsettias are a great improvement over those of only a few years ago. They are vigorous growers, produce multiple blooms, and hold their leaves and their flowers last long after Christmas.
The flower of the poinsettia is an example of the great versatility of nature. The red “petals” are really leaves or bracts. They are green at first and then turn red as the real flowers develop. The true flowers are inside the knob-like bumps in the center. Each of these bumps ~ called a cyathium ~ contains a single female flower surrunded by a cluster of male flowers. Each cyathium also has a prominent yellow gland that produces nectar. This combination of nectar and the surrounding brilliant red bracts is an irresistible attractant for insect pollinators in nature.
To get the maximum satisfaction from your Christmas poinsettia, make sure that it doesn’t dry out. But at the same time, don’t keep it sitting in water. Each day test the soil for proper moisture content with your finger down the side of the pot an inch or two. While the poinsettia is “in flower” it requires a considerable amount of water. Keep the soil moist, but not soaking wet.
Poinsettias, like people, don’t like drafts. Keep them away from an outside door where they will receive a blast of cold air each time the door is open. Also keep it away from hot air vents. Since the poinsettia is a warm-weather plant, it is important that the room be kept at 70˚ to 75˚. Keep the plant in bright, indirect sunshine, but don’t place it in a sunny window for more that a few hours a day.
Have you ever thought of poinsettias as cut flowers? They can be used in cut flower arrangements if they have been treated properly. As soon as half of the small yellow flowers in the center have opened, cut the stems to the desired length. After cutting the stem, you will notice white latex oozing from the latex tubes. To prevent further loss of the latex and to prolong the vase life of the flower, dip the cut ends of the stems in boiling water, approximately two inches deep.
The boiling water coagulates the latex in the tubes and forces out any that may have been pulled into the base of the water-conducting cells. When this treatment is not given, the latex apparently plugs the water-conducting tissues causing the flowers to wilt soon after cutting.
On final note on poinsettias. They are NOT poisonous. You will often find them on lists of poisonous house plants, but they are not considered dangerous. Toxicity research done at Ohio State University a number of years ago determined that poinsettias were not poisonous.
There are other plants that can serve in the role of “holiday” plants. Many of them are available at florist shops, garden centers, supermarkets and greenhouses for the Christmas season. For example, consider the amaryllis. This flower can be bought in any stage of growth from a single bulb, all the way to the semi-opened or “puffy bud” stage.
If you purchase one be sure that one third of the bulb is above the soil line in the pot. Place it in a sunny, warm location and watch the leaves unfold and the flower stem stretch. Keep the growing medium that the bulb is in on the dry side ~ don’t over-water it. Since the amaryllis is a tropical plant keep the room temperatures above 60˚ and in high intensity light. If the plant does not receive enough light, its leaves and flower stem will stretch or elongate too much and fall over.
It takes an average of four weeks from the time the bulb is planted until it flowers. When you see the first flower bud begin to swell and turn color, it will only be another day or two until it completely opens. As a general rule the larger the circumference of the bulb, the more flowers you will get. Larger bulb sizes (10 inches or more in circumference) will give you at least four flowers. Amaryllis flower colors range from white and pink to orange.
Kalanchoes are another holiday plant that is tough and can endure in our homes for a couple of months during the winter. If you compare the leaves of the kalanchoe to the common jade plant, you will notice a resemblance. They both have thick, firm, fleshy leaves. However, the kalanchoe’s are more flattened and tightly packed than the jade plant.
The kalanchoe likes it hot and dry. If you need a plant that can take being in a hot room (like where the wood stove is located) or drafts from the nearby radiator or heat vent, this plant will do well. You can even forget to water it sometimes, however if you do, flowering will be reduced. When choosing your kalanchoe, look for a minimum of two to three flower clusters on a four inch plant, and four or five on a six inch plant. Make sure that the plant has lots of color and little or no dead flowers.
If you, or someone you know likes begonias, consider getting a Rieger begonia. They look very similar to the garden tuberous begonias. Reigers are relatively tolerant of sun exposure and temperature. They do prefer a slightly moist, but not sopping wet media, to grow in. Single and double flowers can be found on the same plant. The measure of a high quality plant will be one that is at least half covered with flowers.
African violets are always popular as a holiday gift plant, but have you considered purchasing a close relative ~ the Gloxinia? They are large, low-growing and spreading plants with small, trumpet shaped flowers.
You can treat gloxinias like African violets. Avoid high-intensity, direct sunlight and water them from the bottom of the pot with warm water. Never water African violets or gloxinias from the top of the pot as this will encourage stem rot in the plant. Keep the soil moist but not waterlogged and avoid cold and hot drafts.
Look for plants that have at least three to five open flowers and at least that many more buds growing in the center of the plant. A six inch gloxinia will have a dozen or more buds and will continue to flower for three to four weeks if properly cared for.
If you allow the plant to dry out or you have located it in a room that is too dark, the flower buds will fall off. Gloxinias come in a wide flower color range of whites, purples, pinks and bi-colors.
Colorful fruiting plants are also popular holiday plants. Ornamental cherries and peppers display vivid yellows, reds, and oranges as fruit colors. These plants prefer a sunny location and even soil moisture. They will flower and retain their fruit longer than many of the holiday flowers. Depending on the species, they can be potentially poisonous so don’t garnish your Christmas or New Year’s salad with the fruit from these plants.
Whether you buy a flowering plant, a fruiting plant or an herb as a holiday present, buy the freshest plant possible. Avoid extremes in temperature and light when locating them in the house. If, when taking the plant home the outside temperature is less than 45 degrees, have the plant sleeved to protect it. If possible, buy these plants last on your shopping trip. Do not leave them in a cold car while you continue to shop. Only an hour or so of exposure to cold temperatures can result in leaf and blossom drop.
Happy gardening and happy holidays!

Marc Teffeau is the Director of Research and Regulatory Affairs at the American Nursery and Landscape Association in Washington, D.C. He lives in Preston with his wife, Linda.