Nasturtium, Tropaeolum majus
Distinctive appearance, rapid growth, and easy culture characterize this once popular annual. Nasturtium flower buds are sometimes pickled or used for seasonings because of their mustard oil. Unripe seed pods have a peppery flavor somewhat like watercress, and may also be used in salads.
Nasturtiums are grown as cool-season temperate plants. In Texas, the seed is usually planted about the time of the average last frost. They are usually planted where they can be allowed to mature, since young seedlings can be difficult to transplant. Seedlings started in small individual pots indoors or in the greenhouse can, however, be set out earlier, and provide a longer bloom season.
Nasturtiums are natives to the cool highlands of mountains extending from Mexico to central Argentina and Chile. There are both climbing and dwarf bush types. The dwarf types are much more commonly available, and are useful as 10- to 12-inch tall borders or as mass plantings in sun or partial shade. Flowers range in color from creamy white to orange, mahogany, red, and yellow. Double-flowered forms are also available.
Nasturtiums actually do better in soil of moderate-to-low fertility, and prefer well drained conditions. The seed are large and sprout quickly. In most of Texas, nasturtiums bloom until really hot weather begins, usually in June. The climbing or trailing kinds can quickly cover fences, banks, or stumps, and are excellent in the winter greenhouse as a source of cut flowers and ornaments. The flowers have an unusual and refreshing fragrance.
Few insects or diseases bother nasturtiums, and they add a touch of old-fashioned charm as borders in vegetable gardens or as potted specimens or mass plantings. They are also a good choice to mix with spring-flowering bulbs, since they can effectively hide the unattractive bulb foliage that may be allowed to mature.
Nasturtiums are at their peak of flowering in Texas during May and June. If you have not grown them before, look for places now where they can be planted early next spring. Few plants offer so much for so little.