How to Grow Nasturtium from Seed to Flower

Nasturtiums are beautiful additions to gardens. They grow from seed, require very little care aside from watering, and all plant parts are edible. Nasturtiums also make excellent companion plants for the vegetable garden. They are so easy to plant that they make a perfect choice for a children’s garden. We have all the details on how to grow nasturtium from seed so that you can include these incredible flowers in your garden this summer. 

Many people know that nasturtiums have edible flowers, but did you know that even the stems and nasturtium leaves and seeds are edible? The plants have an excellent peppery taste, and the flowers are lovely additions to salads. In addition, the seeds are often used as a substitute for capers and are sometimes called “poor man’s capers.” The flowers are also high in vitamin C!

Planting Nasturtiums in The Garden

Nasturtiums are succulent leave annuals native to the highlands of central and south America. Nasturtiums are fast-growing plants with many brilliantly colored single or double flowers. Plant breeders have developed many types of these popular annual plants divided into three different types of nasturtiums. To successfully grow nasturtium from seed, your first step is to choose the variety you want to grow.

• Learn More: Did you know that Nasturtiums are edible? Check out this post about edible flowers to learn more!

Dwarf varieties – Busy types feature compact growth. They grow 10-12 inches high with a 1-2 feet spread.

Semi-trailing cultivars are compact but trail somewhat and grow 1.5 to 2 feet with a spread of 2-3 feet.

Climbing nasturtiums- These plants use their leaves and stalks around supports. Climbing or vining cultivars grow 8-10 feet with 2-3 feet spread.

• Learn More: For more information check out our full guide to growing climbing nasturtiums!

Grow Nasturtiums in the right environment

To grow any flower or plant well ensure that you have chosen the right environment for the plant to thrive. Nasturtiums are not very fussy, but some environmental tips will help you get the best blooms. The plants will bloom continuously from early summer through fall, although they may stop blooming during very dry, very hot spells.

Hardiness

Nasturtium plants are tender annuals that are very susceptible to frost. They grow best in areas with dry, cool summers.  

Light

Grow nasturtiums in full sun where summers are cool and in partial shade where summers are hot and dry.  

Plants grown in the shade will not produce as many flowering blooms as ones grown in full sun.  

Soil 

Nasturtiums like sandy dry, well-drained, poor soil. If planted in fertile soil, the plants will have lush leaf growth of greenery with very few flowers. Look for soil pH from 6-8. Although they tolerate dry soil well, they will wilt during harsh drought conditions.

Planting and Propagation

Planting

It’s actually easier to grow nasturium from seed than it is to transplant them. Direct sow nasturtium seeds outdoors in late spring after all danger of frost has passed. Plant seeds 1/4 inch deep. Seedlings should emerge in 7-12 days.  

Seeds planted before the soil has not warmed adequately may not germinate, so be sure the soil temperature is at least 65F before planting outdoors. 

Nasturtiums are difficult to transplant and do not like their roots disturbed, so direct planting is advised over starting early indoors.

However, you can start indoors in pots planted directly into the soil, like peat pots or choir. Start in early spring 6-8 weeks before the last frost in your area. 

propagation

You can take cuttings from young shoots in fall to grow indoors over winter, but it’s so easy to grow nasturtium from seed that I unusually just plant seeds directly.

You can also collect seeds at the end of the growing season. Seed pods are easily found on the ground under leaves or lying on the garden bed. To save the seeds, dry them in a cool dark place for four days and then add them to a seed packet to save and plant next spring.

Container gardening 

Nasturtiums will grow in containers, window boxes, and hanging baskets. Nasturtiums make a lovey front addition with perennial plants in a garden bed or border or trailing through a herb garden.

Companion Planting Nasturtium

Tropaeolum majus (common name nasturtiums) make lovely companion plants in the garden and often act as a trap crop for pests like flea beetle and aphids. They also help repel squash bugs and cucumber beetles. Nasturtiums are also a protective ground cover that acts as a living mulch to keep the soil cool and moist. They also attract beneficial insects like bees, ladybugs, and parasitic wasps. Nasturtium companion plants range from cucumbers and squash to beans, broccoli, pumpkins, and kale, to name a few.

See: Companion Planting with nasturtiums the complete list.

Recommended nasturtium varieties

Whirlybird series – These plants have semi-double flowers atop bushy plants that have a spectacular display of color. The plants come with bright green round leaves with cherry, gold, mahogany, orange, peach, and scarlet red flowers. Gorgeous as a border bedding plant. These plants will bloom prolifically all summer long.

Glorious Gleam Mixture: A good choice If you are looking for a trailing type of nasturtium. This plant has large, lightly scented, semi-double, and double flowers. We like to add these to the corners of vegetable beds and let them trail on the paths.

Caring for Nastrutums 

Nasturtiums require very little direct care. They are trouble-free plants once they are established.   They also make a great addition to your bee gardens to help keep the bees fed all season long.

Water

Plants require 1 inch of water a week, either through rain or direct watering. However, the plants can be very drought tolerant in areas with cool summers.

Fertilizer

Do not fertilize nasturtium. Excess fertilization will result in lush green leaves and extra foliage at the expense of flowers. 

Flower Cuttings & Drying

You can cut nasturtiums blooms for short-stemmed bouquets.

The flowers are best dried by pressing as the delicate blooms do not hold up well to hang drying or the silica gel method.

Common Insect Pests

The lack of garden clean-up sometimes encourages insects and diseases. Debris laying around the garden can create welcoming environments for pests to thrive. You can decrease the likelihood of inviting problems to feast on your nasturtiums by regular garden clean-up.

Caterpillars

If you find holes in the leaves or leaves with what looks like chewed edges, you may have caterpillars.

Mild infestations are easy to control by handpicking the caterpillars off the leaves and flowers and dropping them in a jar of soapy water.

To control severe infestation, you may need to apply Bt (Bacillus thuringiensis) every 3-5 days until the infestation is under control.

flea beetle

Flea beetles are drawn to nasturtiums, and in some gardens where flea battles are a challenge, nasturtiums are planted as diversionary companion plants. Essentially you sacrifice your nasturtium to the flea beetle to protect your other crops.

If hundreds of tiny holes perforate your leaves, you likely have flea beetles.

The bugs are tiny, with shiny black bodies, and are quite active. They will jump if disturbed. Try to control flea beetles as soon as you find an active infestation. The bugs spread viral and bacterial diseases.

Beneficial nematodes added to the soil will help reduce cycles of flea beetles as the nematodes feed on the larvae.

You can use Pyrethrum every 3-5 days until the infestation is under control.

Pyrethrum is highly toxic to bees. If you need to manage a severe infestation, spray after 9 pm and before 5:00 am to ensure bees are safely tucked away in their hives.

leafminers

Leafminer damage looks like lines or tunnels through the leaves of your nasturtiums. Generally, they do not do much damage unless the infestation is heavy.

However, the damage to the leaves can invite fungal rots and other diseases.

Pick off infected leaves and destroy them. Do not add to the compost heap.

You can treat leaf miners with insecticidal soap every week through June and July.

slugs and snails 

If you live in an area where slugs and snails are an issue, you already know how quickly a small infestation can cause significant damage. Slugs, in particular, can be one of the most frustrating pests to have in your garden.

Nasturtium with ragged holes in the leaves and stems are likely infested with slugs or snails. A shiny trail of slime is a strong clue that the pests eating your precious plants are indeed slugs.

Slugs and snails are active only at night, so they are hard to see and control during the day.

Be sure to remove all debris like leaves, boards, rocks, and garden clippings around your nasturtiums to eliminate the places where they like to hide. You can lure slugs with bait and traps; the key is to start baiting and trapping early in the season to prevent population growth.

Slugs also dislike sand and copper sheeting, so surrounding your plants with either of these materials may help prevent damage.

Spider mites 

Tiny yellow dots are a sure sign that your nasturtiums are infested with spider mites. Spider mites are tiny pests that eat the chlorophyll out of the leaves; unfortunately, they inject the leaves with toxins (double whammy!), which causes distorted and discolored leaves.  

You may also see the plants coated in fine silk webbing either under or over the leaves. 

It would be best to destroy severely infected plants. Do not add to your compost bin.  

Common Diseases that Impact Nasturtiums 

Bacterial leaf spot

Bacterial leaf spot is unsightly but will not usually kill the nasturtiums. The bacteria will cause dark spots on the leaves that rot entirely through.

Pick off and destroy any leaves as soon as you notice them on your plants.

Be sure to clean the area in your garden clean and remove any debris before it has a chance to breed disease.

A layer of mulch will help prevent bacterial leaf spots from infecting the plants.

Bacterial Wilt

If your plants turn yellow, wilt, and die, you likely have a case of bacterial wilt; you can confirm bacterial wilt in nasturtiums by cutting a stem close to the root. If it oozes a mass of grey bacteria, you have bacterial wilt. 

Overcrowing and overwater are two common causes of bacterial wilt in the garden.  

Remove infected plants entirely from the garden, including the soil where the plant was growing. Do not compost, but place it in a tied plastic bag and add to the garbage.  

Be sure to sanitize your garden tools after cutting any plant infected with bacterial wilt. 

Grow nasturtium from seed to flower

Hopefully you’ve learned everything you need to know to help you grow nasturtium from seed. These flowers are easy to grow and maintain, and are wonderful companion plants for the rest of your garden plants.

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