Growing nasturtiums from seed is easy and the carefree plants thrive in garden beds as well as containers. They bloom heavily for months, with the pretty, cup-shaped flowers attracting bees, butterflies, hummingbirds, and other pollinators. In this article you’ll learn two easy methods for growing nasturtiums from seed, get expert growing tips, and discover my favorite varieties for the garden. 

Why grow nasturtiums

If I could only grow one type of annual flower, it would be nasturtiums. Not only are the heat-loving plants easy and fast to grow from seed, but they’re also incredibly attractive with rounded leaves and brightly colored blossoms. Depending on the variety, nasturtium flowers are red, burgundy, orange, gold, pale yellow, purple, salmon, pink, or cream. Certain varieties have solid colored blooms while others have eye-catching varigations, streaks, or splotches.

Nasturtiums are low care plants, native to South and Central America, and grown as annuals, but in zones 9 to 11 they’re perennial. This old-fashioned plant isn’t just for show because the flowers, leaves, and seeds are edible and have a peppery taste. I love them in mixed salads where they add a welcome zing to more mild flavour greens like lettuce.

Types of nasturtiums

Nasturtiums are typically divided into one of two main types and this is based on their growth habit: mounding or trailing.

• Mounding – Mounding nasturtiums grow about a foot tall and a foot or two wide and I like to use them as edging plants in my raised vegetable beds. The ‘Baby’ series of nasturtiums, which includes Baby Rose, Baby Gold, Baby Red, and Baby Yellow, are ultra compact varieties that create a dense mound of pint-sized foliage and flowers.
• Trailing – Also called climbing nasturtiums, these vigorous plants produce lengthy stems that grow 5 to 6 feet long. They make a great ground cover in garden beds, use them to trail over the side of a large container or hanging basket, or direct their growth up trellises, fences, and tunnels. 

For more advice and tips on growing nasturtiums from seed watch this video: 

The best site for growing nasturtiums from seed

As warm season plants, nasturtiums need full sun and well-draining soil to grow and flower well. Avoid shady sites, as well as those that have very damp soil. I grow nasturtiums in all my gardens; raised vegetable beds, patio pots, herb gardens, perennial gardens, and cut flower beds. The graceful growth and cup-shaped flowers add cottage garden charm to any space. 

Timing for growing nasturtiums from seed

Don’t rush planting nasturtium seeds into the garden. They’re best seeded or transplanted outdoors after the danger of frost has passed in spring. The ideal temperature for germination is between 55 and 65 degrees Fahrenheit (13 to 18 degrees Celsius). 

If you wish to start the seeds inside to get a jump start on the growing season, sow them in cell packs, soil blocks (made with a soil blocker), or 4 inch diameter pots 4 weeks before the last frost date. More on planting techniques below. 

Growing nasturtiums from seed: Two easy options

There are two easy ways for growing nasturtiums from seed. The first is to direct sow the seeds outdoors in gardens or pots. The second method is to start the seeds indoors under grow lights or in a sunny window. Let’s look a bit closer at these two options.

1. Direct sowing – Direct sowing is simply planting seeds outdoors in the garden or in containers. Most gardeners direct sow nasturtiums seeds with the plants germinating in 7 to 10 days, depending on the soil temperature. Sow seeds a 1/2 to 1 inch deep, spacing mounding varieties 6 inches apart and climbing varieties 12 inches apart.
2. Starting seeds indoors – I start many types of annual flowers indoors under grow lights, but I don’t bother sowing nasturtium seeds inside. This is because they don’t transplant well and are very quick to grow when direct sown. If you wish to start the seeds indoors, plant them a month before you intend to move them outside. They need darkness to germinate so make sure they’re buried at least a half inch deep in the growing mix. 

Growing nasturtiums in pots

You don’t need a big garden for growing nasturtiums from seed as they thrive in a container, window box, or hanging basket. Start by choosing a container that has drainage holes because nasturtium plants need well draining soil. Soggy soil causes root rot and poor plant growth. Next, fill the pot with a high-quality potting mix.

Both mounding and trailing nasturtiums perform well in containers, but you don’t want to overcrowd the plants. In a 12 inch diameter hanging basket or container, sow 4 seeds of a mounding nasturtium variety, or 3 seeds of a trailing nasturtium variety. For my mixed planters, I like to tuck a few nasturtium seeds at the edge of each pot. As the plants grow, they’ll spill over the containers for an attractive display.

In window boxes and other types of rectangular planters, sow the seeds 6 to 12 inches apart, depending on the type of nasturtium. Spacing is 6 inches for mounding types and 12 inches for trailing varieties.

Caring for nasturtium seedlings

Whether your nasturtium plants are growing in raised beds, in-ground gardens, between established perennial plants, or in pots, here are some tasks to promote healthy growth and loads of flowers. 

• Watering – Frequency of watering depends on the weather, soil type, and how you’re growing the plants. For example, container grown nasturtiums need to be watered more often than those grown in garden beds. To determine whether it’s time to water, stick your finger into the soil. If it’s dry two inches down, deep water. I use a long-handled watering wand to irrigate my plants. 
• Fertilizing – Nasturtiums have a well-earned reputation for thriving without fertilizer. In fact, too much fertilizer can promote excessive leaf growth and fewer flowers. My strategy with nasturtiums is to add a scant half inch of compost to the bed before planting and nothing else. 
• Deadheading – Removing spent blooms helps promote new flower bud formation. I use my fingers or garden snips to snap off the stems of faded flowers a couple of times a week. 

Nasturtium pests

Nasturtiums are widely used for companion planting as they attract many species of beneficial and predatory insects. They’re also planted in vegetable gardens to act as a trap crop luring pests like aphids away from nearby crops. I don’t mind sharing my nasturtiums with a few aphids, but if you notice the population soaring, you can knock the pests from the plants with a jet of water from your hose. Also keep an eye out for whiteflies, slugs, and leaf miners.

Harvesting nasturtiums for the kitchen

Nasturtiums aren’t just for garnishes, as the blooms are popular edible flowers and the rounded leaves are tasty in salads and other dishes. It’s best to harvest in the morning when the flowers and leaves are well hydrated and the flavor is best. For garnishes, I leave the flower intact, but if I’m adding them to salads, I just use the petals as the base of the flower has a bitter taste.

The best nasturtiums to grow

I’m always on the lookout for new or new-to-me varieties of nasturtiums to grow and each year I find myself planting more and more nasturtiums. I love classic mixes like Double Dwarf Jewel and Whirlybird, but it’s also fun to grow nasturtiums with unique flower colors or leaf variegations. Here are my five favorite varieties to grow:

1. Aloha Mix – Aloha Mix is a unique blend of tropical hued flowers in shades of pink, cream, butter yellow, and apricot. They jazz up patio pots as well as garden beds attracting pollinators, hummingbirds, and butterflies. 
2. Alaska Mix – This classic collection boasts yellow, red, salmon, cherry, and orange flowers, but is remarkable for its distinctive variegated leaves. The white streaks on the leaves of Alaska Mix add extra interest to the garden and containers.
3. Bloody Mary – When you grow Bloody Mary nasturtiums you’ll discover that no flower is the same! They range from pale gold with dark burgundy blotches to solid blood red and everything in between. The petals are uniquely flecked, streaked, and splotched and the deep blue-green leaves provide the perfect backdrop to the dramatic blooms.  
4. Orchid Flame – These mounding nasturtiums have bright yellow flowers that are splashed and streaked with deep red, almost as if painted.
5. Trailing Mix – This is the variety to grow when you want your nasturtiums to grow on a trellis or fence. Growing up to 6 feet, the long branches can be directed up supports or let them sprawl along the ground. They also look delightful spilling down rock walls or the edges of hanging baskets. 

Other outstanding nasturtiums include Peach Melba, Empress of India, Cherries Jubilee, Buttercream, and Phoenix. 

For more information on growing nasturtiums and other annual flowers, be sure to read these articles:

• How to grow climbing nasturtiums
• Planting and growing strawflowers
• When to plant sweet peas (and a how-to guide!)
• Growing zinnias from seed: 3 options

Are you going to be growing nasturtiums from seed?