Winter Annuals (cont)
By: Charlie Nardozzi
Growing annuals in winter is a bit different from growing them in other seasons. Light levels are lower and plant growth slower. Plants such as pansies that normally would shun the bright sun are more tolerant of full sun. Although temperatures may rarely drop to freezing, the cooler air and generally more frequent rains tend to keep the soil moist longer.
In cool, moist soils you'll need to adjust your fertilizing schedule and take steps to prevent rot diseases. In containers, use a light soilless mix. In gardens, improve drainage with raised beds, especially if you live in a wet area with heavy soil. Cold, wet roots are a sure way to rot plantings. Remove summer mulches such as bark; don't till them into the soil. Incorporating high-carbon mulches will create a nitrogen deficiency in the plants.
At the nursery, choose plants (November is too late to sow seeds) that are already flowering or have obvious buds. Annuals that haven't set flowers by November are not likely to flower well all winter. Set out various combinations of plants as soon as you can, remembering that plants will not grow fast in winter so spacing can be a bit closer than normal. Fertilize sparingly with a fertilizer containing a nitrate form of nitrogen, such as calcium nitrate, during the season. Nitrogen fertilizers containing ammonium can cause leggy growth during brief warm spells, but when the soil cools below 45° F, the nitrogen becomes unavailable to plants. Reapply mulches in drier winter areas such as the desert Southwest. Now just sit back and enjoy a winter season of beautiful flowers.
Charlie Nardozzi is a senior horticulturist at National Gardening.
Photography by National Gardening Association and Suzanne DeJohn.