Can Nasturtiums Make It Through Winter?

Planting Zones

• The continental U.S. and some southern parts of Canada are divided into planting zones that indicate how much cold a plant species tolerates. In areas that experience all four seasons, indicated by zones 1 through 8, flowers such as nasturtiums are grown as annuals and cannot tolerate the cold. Started in mid-spring, they grow and bloom until the first frost, which kills them off. In zones 9 through 11, they can be planted any time of the year, with a recommended planting time of November to March.

Self-Propagation

• Nasturtiums very often self-seed, which means that the parent plants drop seeds which, in warm areas, sprout immediately and grow into new plants. In more temperate areas, such as zones 5 through 8, where a frost kills the plants, the seeds may remain in the soil and germinate the following spring, especially during a relatively mild winter. In such areas, while the parent plants themselves don't make it through the winter, their seeds very well may, surprising gardeners in the spring with a new crop of the same variety as the original plant.

Growing Nasturtiums

• Of all the flowers grown primarily as annuals, nasturtiums are among the easiest to grow. Their wrinkled seeds are large, measuring roughly 1/8th to 1/4 inch in diameter, and they sprout just days after planting. Soaking them in warm water the day before planting speeds the process up even more. Nasturtiums don't need much in the way of soil preparation, but they do best in loose rich average garden soil and produce good results in even poor soil. Plant seeds from 1/2 to 1 inch deep, spacing them about a foot apart in the ground or about 6 inches apart in pots or hanging baskets, which are particularly well suited to the nasturtium's long trailing vines. Provide at least 6 hours of sunlight a day, and water 2 to 3 times a week. After the first frost or the vines have withered, harvest the seeds, which will be clearly visible at the tips of small new shoots, and discard the plants.

Varieties

• Nasturtium varieties grown include Alaska, that trails to 15 inches, producing orange, red, salmon or yellow flowers; Canary creeper, that climbs to 15, produces bright yellow flowers, and is grown as a year-round perennial in zones 9 and 10. Jewel of Africa nasturtium (Tropaeolum majus 'Jewel of Africa') climbs to 5 feet, has variegated foliage and red, gold, cream, or peach blossoms, while Peach Melba is a bush variety producing cream flowers with red throats. Seed mixes containing several varieties are also available for mass plantings and borders.

Fun Facts

• A member of the green cress family, all parts of the nasturtium plant, including the stems, leaves and blossoms, are edible. Like cress, they have a decidedly peppery flavor when added to salads or sandwiches. Warm weather intensifies the flavor, and all parts of the plants can be harvested before the first frost and frozen for use in stir-fries and pasta dishes. For a milder flavor, pick the flowers, buds and newer leaves early in the morning.