Week of October 6, 2003
Submitted by Calvin Finch, Ph.D., Conservation Director, San Antonio Water System, and Horticulturist
It is time to plant most of the cool weather blooming annuals. Petunias, snapdragons, dianthus, stocks, calendula, alyssum, and ornamental kale do best over the winter and in early spring if they are planted now. Pansies, cyclamen, and primula are more sensitive to hot weather than the other species so usually perform best if they are planted in November.
Ornamental kale has some shade tolerance. Cyclamen and primula require shade to survive but, for most of the blooms listed, a site in full sun is required. Raised beds filled with a compost-rich landscape mix is best but 3 or 4 inches of compost incorporated into native soil may also work. Most winter annuals also do well in containers. The bigger the container the better the plants perform, but alyssum, pansies, dianthus, and even the floral carpet snapdragons perform acceptably in 10-inch hanging baskets.
Prepare the soil in raised beds and landscape beds with a cup of slow release lawn fertilizer spread over 50 square feet of bed. Use Osmocote or one of the other slow release fertilizers prepared especially for containers in your pots. Expect to water the new transplants every day for a week and then weekly after the plants are established if it does not rain much. The best test is to feel the soil; if it is dry to 1 inch it is usually time to irrigate. A fine mulch and drip irrigation make the process easy and efficient.
If you have deer in your neighborhood, snapdragons and stock are the best choice for winter color. Pansies are a favorite deer food. Some of the new petunia varieties such as VIP and Laura Bush have foliage that is unpleasant enough to deer that they may pass it up in some situations.
Slugs, pill bugs, and snails feast on the low-growing winter annuals. Primulas are especially savaged but pansies are also readily eaten. Control the pests with slug and snail bait spread every week or prepare beer traps. Sink plastic cups into the group so the top is level with the surface. Fill The cup half full with fresh or stale beer. The slugs, snails, and pill bugs will quickly fill up the cup as they seek the beer bait. A trap every 4 feet does a good job of control. There does not seem to be any advantage to using expensive beer over cheap beer, or light over regular beer. The usual practice is to use your favorite beer so that you can take a few nips as you refill the traps.
The best winter annuals for borders are alyssum, pansies, floral carpet, snapdragons, and some selections of dianthus. They are all small plants and bloom steadily through the season unless there is a long spell of cold weather. Ornamental kale and cabbage are the most formal winter annual. They grow uniformly and do well in lines or evenly spaced mass plantings.
Alyssum is the most fragrant of the choices. You can often find it at your favorite nursery by just following your nose. My favorite winter annual for fragrance, however, is stock. This old-fashioned flower makes a nice bouquet for the house and provides a pleasant light perfume. Some of the pansies are also fragrant.
The larger snapdragons make spectacular cut flowers. The colors are intense and the flowers cover the stalks. The larger snapdragons like Rocket produce well in 5-gallon or larger containers supported by tomato cages. If you grow them in a bed protect them from the wind by planting them en masse or against a wall or another sturdier plant.
Pansies have the most cold tolerance of the winter annuals listed and petunias the least. Pansies will keep blooming through a relatively long spell of cold and even short spells of freezing temperatures. Snapdragons, calendula, and especially petunias quit blooming in the middle of the winter.
Whatever your preferences and growing conditions, there are some suitable choices for winter color in San Antonio. Improve your landscape by planting your favorites this winter.