How to Grow and Care for Nasturtium

Nasturtium plants include more than 80 perennial and annual flowering species in the Tropaeolum genus. These herbaceous flowers are native to South and Central America and are known for their rich, saturated, jewel-toned colors. The rounded leaves look like miniature lotus leaves.

In most North American climates, nasturtiums are grown as annuals. There are nasturtium varieties for almost every gardening purpose: bushy ground-hugging for borders where they fill bloom gaps in a sunny perennial garden, trailing plants for edges, that spill beautifully over walls, edges, and containers, and climbers that add dramatic height. The leaves and flowers are edible, with a peppery tang.

Planted in the spring after the threat of frost has passed, nasturtiums are fast and easy to grow.

Nasturtium is a popular companion plant in vegetable gardens where it attracts pollinating insects and keeps pests away.

Nasturtium Care

Nasturtium Tips for Beginners

• How to Start: Start nasturtium from seed or purchase starter plants.
• When to Plant: After there is no more danger of spring frost.
• Where to Put: Plant in full sun and fairly infertile soil with good drainage.
• When to Water: In the garden, water about once a week and potted plants more often.

Light

Nasturtiums grow and bloom best when planted in an area of full sun that receives six to eight hours of direct sunlight daily. They tolerate some shade (only three to six hours of sunlight), but might not bloom as profusely. However, when planted in a warm climate, some shade is preferred, as hot temperatures may end up browning leaves.

Soil

Nasturtiums do well in relatively infertile soil with good drainage. Soil that's too rich will result in abundant greenery, but few flowers. This plant grows best in soil with a neutral pH (6 to 8).

Water

Nasturtiums prosper with about 1 inch of water per week but should be watered more often when planted in pots or a sunny vegetable plot where the soil dries out more quickly. Nasturtiums will survive moderate droughts, but blooms will likely diminish and the foliage will begin to look spindly.

Temperature and Humidity

While some varieties of nasturtium are planted as perennials in USDA growing zones 9 through 11, in most North American climates, they are annuals. The plants do best in daytime temperatures in the 70s and survive a light frost though not temperatures below 32°F, with an average humidity between 30 and 50 percent. Nasturtiums struggle in extremely dry or extremely humid conditions.

Fertilizer

There is no need to fertilize nasturtiums, as rich soil causes nasturtiums to grow more foliage and fewer flowers. If the soil is very poor or the surrounding vegetables need a boost of nutrients, amend the soil with organic matter before planting.

Types of Nasturtium

Nasturtiums have different growth habits, ranging from mounding, bushy varieties to trailing or climbing types. The most commonly grown nasturtium species, Tropaeolum majus, has rounded, shield-like leaves with colored blooms peek out behind their greenery. The flowers are funnel-shaped and come in varying shades of yellow, orange, pink, and red. Certain varieties boast subdued shades of butter yellow and cream, and others have variegated leaves.

Of the dozens of species of nasturtiums, favorites include:

• The 'Alaska' Series' is a colorful heirloom variety with variegated foliage that holds different colored blossoms above its leaves. This bushy dwarf plant thrives in poor soil conditions and reaches a compact spread of 8 to 10 inches.
• The 'Jewel' Series' grows vigorously to a height of 16 inches and produces different colored flowers in yellow, red, orange, mahogany, and rose. This mounding variety is a profuse bloomer, but the flowers tend to get lost under the foliage.
• 'Peach Melba' has two-toned—yellow with maroon spots near the center; they taste like watercress. This bushydwarf plant works well in containers and has a mature height and spread of 10 to 12 inches.
• 'Canary Creeper' (Tropaeolum peregrinum) is a trailing nasturtium species with vines reaching 8 to 12 feet in length. It should be planted near fences or trellises where it can climb. The bright yellow flowers resemble the wings of a canary bird and the edible leaves are deeply lobed.

Nasturtiums as Companion Plants

• Plant next to zucchini, summer squash, watermelons, peppers, broccoli, cauliflower, cabbage, radishes, lettuce, asparagus, parsley, basil, and dill
• Acts as a trap crop for aphids or squash bugs
• Attracts beneficial insects such as hoverflies that prey on aphids, as well as pollinators
• Repels whiteflies, several beetle species, and cabbage loopers
• Avoid planting next to fennel, cucumbers, and rosemary

Pruning

Deadheading of spent flowers is usually not necessary but pinching off spent flowers and dried leaves will aid in the plant's overall aesthetic. Pick the fully opened flowers for use in salads and to garnish summer desserts.

Trailing nasturtium varieties are prone to legginess and usually need pruning mid-summer, and then again in late summer, to stimulate new growth and blooms. Trim the longest stems back by 6 to 12 inches on trailing varieties and thin browning leaves and flowers by pinching them off at the base. For bushy varieties, trimming stems is not generally needed.

Propagating Nasturtium

After pruning your nasturtium, it is possible, and easy, to propagate the cuttings. You may also want to grow a new plant from a cutting if a large portion breaks off or if you want to replant the same variety in another part of your garden.

Here's how to propagate nasturtium from cuttings:

1. Gather garden sheers, a pot with drainage holes, potting soil, and rooting hormone powder (optional).
2. Fill the pot with potting soil.
3. Select a stem from your mature nasturtium plant and cut off a 4-inch (or longer) piece with at least three leaves intact. Dip the cut end into rooting powder (this is not necessary, but may speed up the process).
4. Poke a hole in the center of the soil and insert at least 1 inch of the stem into the hole.
5. Backfill the hole gently with your fingers and water the pot carefully in the sink.
6. Allow the pot to drain and place it in a sunny window or under grow lights.
7. Check for roots in about one week. Once strongly rooted, transplant the stem into your sunny garden and continue to keep the soil moist.

How to Grow Nasturtium From Seed

Seeds can besown directlyin the garden once thesoil haswarmed to at least 55 to 65°F or started indoors two to four weeks before the average last spring frost date. If starting them in pots, use peat starter or other biodegradable pots, as nasturtiums are finicky about transplanting. This will reduce transplant shock.

Plant seeds 1/2 inch deep and 10 to 12 inches apart. Keep the soil continuously moist until seeds sprout, which should take about a week to 10 days.

Potting and Repotting Nasturtium

A good quality potting mix will do but don't use one with added fertilizer, as nasturtium won't bloom in overly rich soil. The plants grow best in natural stone or clay containers with ample drainage. Add a layer of stones or pebbles to the bottom of the pot, before adding soil, to improve the drainage.

Common Pests and Plant Diseases

Nasturtiums attract aphids, which deters the aphids from attacking vegetables and other garden crops that are also vulnerable to aphids. Finding aphids on your nasturtiums is, therefore, a good sign, it shows that the nasturtiums are working as a deterrent. However, if there is an aphid infestation and the foliage looks crinkled or otherwise unhealthy, it might warrant using a strong blast of water from your garden hose to wash them off.

Nasturtiums are prone to contract bacterial leaf spot. The disease is spread by splashing water and manifests itself as small brown or black spots on the leaves. Providing ample airflow between plants and watering with drip irrigation instead of overhead irrigation reduces the risk of infection.

How to Get Nasturtium to Bloom

Nasturtiums begin to bloom when temperatures rise, so make sure your plant is in a sunny, warm location to assure maximum color. If your nasturtium hasn't started blooming within four to six weeks after sprouting, then you may need to wait for the outdoor temperatures to rise, or for weather conditions to improve.

Plants with abundant foliage but no blooms may be an indicator of rich soil conditions. While it's usually not recommended to fertilize this plant, under these circumstances, a plant food high in phosphorous may help promote flowers. Opt for natural products, like bone meal or rock phosphate, especially if you plan on eating the flowers. Pruning your plant may also help if you planted a variety that holds flowers under its leaves.

Common Problems With Nasturtium

Some varieties of nasturtium actually obstruct flower production due to the plant's physical structure. If you are growing nasturtium at ground level, as opposed to one that trails or vines, choose a variety that holds its flowers above its leaves, allowing the sun to get to the buds.

In waterlogged soil, root rot may occur.

From: thespruce