Tropaeolum–commonly called nasturtium–are grown for their brightly colored, trumpet-shaped flowers. Nasturtiums are tender perennials commonly grown as summer annuals. Some nasturtiums are bushy, some are sprawling, and some are climbing.
Nasturtiums add quick color to mixed borders, hanging baskets and containers, or trellises. Leaves vary from bright green to blue-green depending on the variety. Flower colors include cream, yellow, orange, peach, rose, red. Flowers are sometimes veined or splotched.
Nasturtium flowers, stems, and leaves are edible. They have a spicy, mustard-like flavor. Nasturtiums are often added to herb and vegetable gardens.
Tropaeolum is a genus of about 80 climbing, trailing, or bushy annuals and perennials native to mountainous regions of Central and South America.
Get to Know Nasturtium — Tropaeolum
- Plant type: Hardy annual or tender perennial usually grown as an annual.
- Growing Zones and range: All zones during mild weather 50° to 80°F (10-26.7°C), Zones 10 and 11 as a perennial.
- Hardiness: Blooming will stop when temperatures exceed 85°F/29°C.
- Height and width: 1 to 6 feet (1.8m) or more depending on the variety
- Foliage: Leaves are round or lobed and peltate–the stem is attached near the center of the leaf, rather than the edge
- Flowers: Showy, spurred, five-petaled flowers in shades of red, orange, yellow, peach, or cream, sometimes veined or splotches; flowers are attached to leaves near the center of the leaf rather than the edge; flowers are held on slender stems.
- Bloom time: Summer in all regions, all year in frost-free winter regions
- Uses: flower beds, borders, containers, trellis for climbing types, trailing types used as a groundcover
- Common name: Nasturtium
- Botanical name: Tropaeolum majus
- Family: Tropaeolaceae
- Origin: From Mexico to Chile
Where to Plant Nasturtium — Tropaeolum
- Plant Tropaeolum in full sun in Zones 2-6; plant in part shade in hot summer areas in Zones 7-11.
- Grow Tropaeolum in average to poor, well-drained soil, preferably sandy soil.
- Tropaeolum prefers a soil pH of 6.5 to 7.5.
Nasturtium — Tropaeolum Uses
- Use climbing varieties to cover trellises or fences or as a ground cover.
- Use climbing varieties to trail from hanging baskets and window boxes.
- Dwarf varieties are good as edging plants for flower and vegetable beds.
When to Plant Nasturtium — Tropaeolum
- Start seeds indoors 4 to 6 weeks before the last frost, after soaking them overnight in water.
- Germination takes 8 to 12 days. Keep soil at 60° to 70°F (15.6°-21°C) until seeds germinate.
- Sow Tropaeolum seed directly in the garden 1 week after the last frost in spring in Zones 2 to 7. In Zones 8 to 11, sow in late autumn for winter or spring bloom.
Planting and Spacing Nasturtium — Tropaeolum
- Grow in small pots in moist potting soil; sow seed 1/2 inch deep; set pots in full sun or a few inches below a fluorescent light fixture; pot up seedlings when they have four leaves.
- Sow seeds outdoors one to two weeks after the last frost in spring. sow seed in smoothly prepared soil. soil
- Space Tropaeolum 6 to 12 inches (30cm) or more apart depending on the variety.
How to Water and Feed Nasturtium — Tropaeolum
- Tropaeolum needs moderate water; keep the soil evenly moist. Once established, nasturtiums are drought tolerant.
- Fertilize Tropaeolum lightly at planting time. Apply low nitrogen, high phosphorus, and potassium fertilizer when plants are 5 to 6 inches tall.
- Fertilizing Tropaeolum will cause leaves to grow higher than the flowers.
Nasturtium — Tropaeolum Care
- Mulch around Tropaeolum to conserve soil moisture.
- Pinch back tips for business; don’t pinch for longer vines.
Growing Nasturtium — Tropaeolum as a Houseplant
- Tropaeolum majus can be grown as a houseplant.
- Grow Tropaeolum where the temperature is cool, light is direct and humidity is moderate.
- The medium should be soilless, sandy, well-drained, and evenly moist at all ties.
- After the flower buds have formed, fertilize monthly; fertilizing prematurely results in lush foliage and few flowering.
- Vining varieties may be grown in hanging baskets.
- Pinch plants occasionally to keep them compact.
Nasturtium — Tropaeolum Pests and Diseases
- Pests and diseases are usually not a problem; discard leaves that show evidence or leaf miner trails.
- Wash away aphids with a blast of water.
Nasturtium — Tropaeolum Propagation
- Sow the seed of annuals in early spring indoors; sow seed in the garden in mid spring.
- Seeds germinate in 14 days at 65°-70 °F (18°-21 °C).
- Sow the seed of perennials in containers in a cold frame as soon as ripe; germination is often erratic.
- Insert stem tip or basal cuttings of selected cultivars in spring or early summer.
Nasturtium — Tropaeolum Varieties to Grow
- Tropaelum azureum: Tender perennial climber; plants climb to 7 feet and bear pale blu3 1/2 inch flowers in late spring.
- T. majus, common nasturtium, Indian cress: Climbing annual; round, wavy margined leaves, bears 2-inch flowers in shades of red, orange, or yellow; bushy and climbing cultivars. Several cultivars: Whirlybird Series are bushy rather than climbing; Alaska Series plants grow to 1 foot tall, leaves are variegated; Gleam Series grow to 18 inches tall; ‘Jewel of Africa’ climbs to 8 feet; ‘Empress of India’ bear semidouble scarlet flowers on 12-inch plants.
- T. peregrinum, canary vine: vigorous annual or tender perennial; plant climbs to 12 feet; bears yellow 1-inch-flowers; flowers with fringed petals.
- T. poyphyllum: Trailing annual or tender perennial; plants grow to 3 feet; bears deep yellow flowers.
- T. speciosum, flame flower: Tender climbing perennials; dark green leaves and brilliant scarlet flowers.
Nasturtium Frequently Asked Questions
Q: Should I start nasturtium seeds indoors?
A: Nasturtium does not transplant well. Seeds grow quickly and are best sown outdoors where plants are to grow. Sow seeds after all danger of frost have passed. Plant in full sun or light shade.
Q: Why did my nasturtium fail to bloom?
A: Don’t fertilize nasturtium. Fertilizer will result in leafy growth, not blooms. In warm weather, bush varieties bloom better than the vining types.
Q: Are all parts of nasturtiums edible?
A: Yes, seeds, leaves, flowers, and buds are all edible and often used in salads.
Q: Can nasturtium be grown indoors in winter?
A: Yes, nasturtiums can be grown indoors in a cool, sunny window. Plant sees in last summer in a pot in soil without fertilizer. You can also take cuttings to start new plants. Keep plants cut back until winter then allow them to bloom.