Tropaeolum, commonly known as Nasturtium, is a genus of roughly 80 species of annual and perennial plants. Red, orange and yellow Nasturtiums fill a summer garden bed with low-maintenance, ongoing blooms.
Nasturtiums grow quickly and profusely from seed and flower from early spring through mid fall. In addition to producing attractive blooms, Nasturtiums are edible. The flowers and leaves provide a pepperlike flavor in salads or as a garnish.
Nasturtiums grow well in almost any type of well-draining soil. They can tolerate dry conditions and low fertility without damage, but best flowering occurs in slightly sandy but moist soil. Avoid planting Nasturtiums in areas with rich soil that's heavily amended with organic matter, because they flower poorly in nutrient-rich locations. In mild summer areas, Nasturtiums prefer full sun. They need afternoon shade if your area experiences high summer temperatures. Nasturtiums only grow during frost-free weather.
Seeds provide an inexpensive and reliable way to produce Nasturtiums. Nasturtium seeds germinate readily when sown directly in the garden in early spring after frost danger has passed. Seeds require planting at a 0.5-inch (1.3 cm) depth so that they are in complete darkness for sprouting. Space the seeds 6 to 8 inches (15 to 20 cm) apart. Keep the top 4 to 6 inches (10 to 15 cm) of soil moist until the seeds germinate, which takes seven to 10 days when temperatures are between 55 and 65 degrees Fahrenheit (13 to 18 degrees Celsius). If you prefer to use transplants, plant them at the same depth they were growing at in their nursery containers and space them 6 to 8 inches (15 to 20 cm) apart.
Once actively growing, Nasturtiums require only minimal care. The plants don't require fertilization. Applying a fertilizer only results in lush foliage and few flowers. Nasturtiums do benefit from regular irrigation. Water given once or twice weekly, when the top 1 inch (2.5 cm) of soil begins to dry, is usually sufficient. Provide enough water to moisten the soil to a 6-inch (15 cm) depth. Although it's not necessary to prune Nasturtiums, they may spread and become invasive if allowed to set seed. Pinch off the old flowers as soon as they begin to wilt to prevent seed formation.
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