How to Plant, Grow, and Care for Nasturtium

Want something festive and tasty? Nasturtium flowers perfectly embody the vibrancy of summer with their bright red, yellow, and orange and bold, peppery flavor. You’ll love how growing nasturtiums quickly fills empty spaces in your garden – and your plate!

Nasturtiums can be used just about anywhere and are ridiculously easy to grow. They’ll climb up fences, sprawl down walls, edge flower beds, cover the ground, and much more. They’re tolerant of drought and poor soil, don’t need fertilizer, and are rarely affected by pests. They’re also a great choice for growing microgreens. You’ll be able to fit this “plant and go” flower into any space available.

Every part of the nasturtium is edible except for the roots. The leaves and flowers have a strong pepper flavor that will season salads, pasta, cakes, and even soft cheese. They also have great nutritional value, with lots of Vitamin C, beta-carotene, and antioxidants. Historically, this edible was used medicinally (as well as appreciated for its peppery taste!).

So whether you want to liven up your yard, season your food, or eat something healthy, this is the herb for you. Nasturtium is an all-in-one type that’s perfect for any garden!

What is Nasturtium?

When you search the web for ‘Nasturtium’, you’ll find two completely different varieties by that name. The genus Nasturtium is actually watercress, not the peppy flowers we’re growing. Watercress is closely related to mustard and has an oil that’s also found in nasturtium flower buds (hence the shared name). The flowers we’re discussing are called nasturtium in the common name only. Their genus is Tropaeolum, which includes over 50 different species. 

Nasturtium varieties are either climbing, bushy, or trailing. Climbing varieties will quickly spread out over a fence, a stump, or even a hill. They produce less but larger flowers than the bush types. Bush and trailing nasturtium varieties are great for adding quick, colorful bulk to a bed or as a ground cover. All types grow well in containers.

Tropaeolum majus is your common garden nasturtium, usually climbing, and the one we’ll focus on in this article. The other species you’ll hear about the most is Tropaeolum minus, which looks very similar to the majus species, but is generally the dwarf bush type. The care for the rest of the species are fairly similar, but they may differ in size, growth rate, flower appearance, etc.

Native Area

Because it’s native to the Andes mountains in South America, nasturtium is a warm-weather variety. However, it’s also annual, so that it can grow during the summer in areas as cold as zone 2. When planted after the frost has passed, you’ll enjoy a long blooming season from May to September. They die in the fall but usually self-seed and appear again the following spring.

Characteristics

Many gardeners grow nasturtiums just for their ornamental value. The funnel-shaped flowers are vivid shades of red, orange, yellow, and even pink. Each delicate petal is peppered with variegation. Their peppery, floral fragrance attracts butterflies.

Unlike many look-alike garden types, nasturtium is easily recognized by its leaves. They’re round and slightly scalloped with star-shaped veins. You could say they look like green parasols opened in the sunlight. 

Planting

You can start growing nasturtiums outside when the frost is gone in the spring. They can be started indoors about a month early. However, nasturtiums don’t transplant well so you’ll want to use biodegradable pots that can go right in the ground.

Before you choose a spot for growing nasturtiums, take a look at the seed packet. The size varies depending on variety, with some reaching ten feet tall and others only one. Nasturtiums usually spread up to three feet wide, so they’ll also need ample horizontal space.

Nasturtiums are excellent candidates for containers or window boxes. Be sure to choose pots that are large enough for the variety and have drainage holes. If you’re using a climbing nasturtium, the container will need to be hanging or have a trellis.

Nasturtium seeds have thick hulls, which can make germination rather arduous. We can speed up germination and increase the germination rate by scarifying and soaking the seeds. To scarify them, make a small cut into each seed hull, taking care not to damage the embryo inside. The goal is to help the seeds absorb water faster. If you can find the round and devoted spot on the hull that was attached to the ovary, make the cut on the opposite side to avoid hitting the embryo. After that, soak the seeds for two to four hours in warm water. Start sowing them immediately after soaking.

Sow the seeds a half inch deep and 12 inches to 36 inches apart, depending on the variety. In just seven to twelve days, you’ll have a bunch of nasturtium sprouts ready to take on the garden!

How to Grow

Planting was by far the hardest part of growing nasturtiums (if you could call that hard!). It’s so easy to grow nasturtiums that their care will be a breeze.

Light

Grow nasturtiums in full sun for optimal blooms and green foliage. Even though they like the sun, they prefer cooler temperatures during the growing season. You may need to provide some partial shade during the hottest part of the day so they don’t get sunburned or stressed. Ideally, the soil temperature should be 55 to 75°F (13 to 21°C). It only survives to temperatures as low as 20 to 30°F (-7 to -1°C), even without frost present.

Water

Nasturtiums are drought-tolerant, but they still appreciate consistent watering. Keep the soil moist but not soaking, and they should happily grow for you. Depending on how hot it is outside, you’ll probably be watering them one to two times a week.

To prevent pest infestations and disease, only water at the base, such as with a soaker hose. If your nasturtium are growing in a pot, use a watering can with a long, thin spout that can poke between the leaves to the soil mix. Nasturtiums are mostly impartial to humidity, unless it’s in the extremes.

Soil

One of the best things is that you can grow nasturtiums in poor soil and utilize that previously unusable garden space. As long as the soil is well-drained, nasturtiums don’t really care about the texture or fertility. In fact, fertile soil will decrease blossoming. They are flexible when it comes to pH, but prefer a slightly acidic mix.

Fertilizing

Fertilization decreases flowering here, so we’ll save some precious gardening time and skip it.

Maintenance

Pruning is great for keeping your beautiful flowers and foliage in check. For bush varieties, clip back long stems to encourage bushy, green growth and keep the shape compact. Vines that are overstepping their boundaries should also be pruned.

Keep them healthy by clipping off spent nasturtium flowers and old, dying, or diseased nasturtium leaves. Be sure to remove any clippings from the ground when you’re finished.

Climbing nasturtium varieties should be trained to climb, unless they’re in a hanging basket. Provide a sturdy trellis or fence and gently any stray vines onto it. If needed, loosely tie stubborn vines onto the trellis with a fabric scrap and remove it when the vine starts to climb on its own.

Propagation

Because they’re annuals, the most efficient way to propagate nasturtiums is through seeds. They easily self-seed, so as long as pollinators are present you should see seedlings the next spring.

If you’re looking to share your nasturtiums (or score free ones from your neighbor), they will grow from cuttings. You’ll need a three-inch section of stem, starting from the tip, with a few nodes and leaves attached. Trim off any leaves from the bottom one to two inches. Trim the end of the stem at an angle, and stick the cutting in poor soil, perlite, or water. Keep it moist, and you’ll see roots in two to three weeks. After that, you can transplant your new nasturtiums into the garden.

Harvesting

Nasturtium blooms all summer long, so you’ll have a prolific harvest. Here are our top tips to harvest your crop and keep the flowers coming for more gardening.

You can start harvesting the foliage when the nasturtium is six inches tall and harvest the flowers as soon as they bloom. Collect your nasturtium flowers and leaves just as you would an herb. Using clean, sharp scissors, clip off the desired parts as needed. To keep them healthy and actively growing, never remove more than two-thirds at a time, and try to harvest the older foliage. However, if you’re going to use it as a garnish, younger blooms, leaves, and stem tips will taste best.

Towards the end of the growing season, leave some flowers untouched if you want the nasturtiums to self-seed for next year. When it dies off in the fall, remove it from the garden, roots and all, to prevent pests from overwintering there.

Storage

To preserve freshness, hold off on washing the blooms until you’re about to cook with or taste them. Use the blooms and foliage raw for salad and garnishes. If you’re going to cook them, like in stir fry, add them at the very end. Cook with nasturtium seeds like you would capers, using them to spice up sauces, cheese, or potato salad.

Store unused nasturtiums in a sealed container in the fridge and try to use them within five days. Nasturtium flowers will wilt soon after being harvested, so stick them in water like a cut flower to preserve their shape. They can be kept in the fridge this way for a few days.

For long-term storage, you can dry your nasturtiums. Spread them out on a paper towel in a warm spot in your kitchen. Leave them there for a couple days, turning occasionally, until they’re completely dry. When all the moisture is gone, transfer the flowers to airtight containers and keep them in a cool, dark place. Dried flowers will last for on to three years, but are best consumed within the first year.

Common Problems

Most issues with nasturtiums can be solved by neglecting them a little more (it’s usually the opposite when gardening!). But, we’ll take a closer look at some of the most common problems.

Growing Problems

If your nasturtiums, start to turn yellow and die back, especially during the summer, they’re probably too hot. Give them some light shade in the afternoons or transplant them to a cooler location. You can clip back damaged foliage as needed.

Another common problem is the absence of nasturtium flowers. This can happen for a number of reasons. First, it could be that the soil is too fertile for their liking. Another reason is the temperature. Blooms won’t appear until it is four to six weeks old and the temperature gets hot. Nasturtiums need at least a few hours of sunlight every day to produce flowers.

Pests

The unique scent of nasturtium flowers attract aphids. Usually this is a pain, but many gardeners use this attribute to their advantage. When caught early on, aphids are easily removed by a strong spray of water. Nasturtiums hold up well to this, so they’re often planted to distract aphids from more vulnerable species. If the aphids get out of control and the hose just won’t do, try using organic insecticidal soap, neem oil, or ladybugs.

Nasturtiums are also a great trap crop for cabbage moths. These insects will usually target brassicas, so nasturtium would be great planted next to the vegetable garden. Once your nasturtiums have attracted the moths or their caterpillars, remove them from the garden with BT, or diatomaceous earth.

Diseases

Bacterial leaf spot is a Pseudomonas infection that creates water-soaked lesions on the foliage. It’s usually caused by high humidity and a lack of airflow between the leaves. To prevent it, keep your nasturtiums thinned and dry. Once established, there is no remedy for this disease, so you’ll have to remove the infected parts.

The Pseudomonas bacteria can also affect nasturtium roots and cause the whole plant to wilt. Your nasturtiums may also turn yellow, ooze when cut, and have black streaks on the stems. The key to prevention here is soil health. Clear out debris, don’t flood the soil, and rotate crops every year. Any diseased ones, including their roots, should immediately be removed from the garden.

Frequently Asked Questions