Tropaeolum majus, better known as nasturtium, is a popular edible flower that is so much more than a colorful garnish. Nasturtiums are nutritious. They're also reassuringly low-maintenance and will brighten up your garden with their vibrant hues and circular green leaves. Native to South and Central America, they prefer conditions that mimic their jungle origins. These five-petaled flowers tend to come in warm shades that mirror the warmth of their growing environment, and they can bloom throughout the year when the conditions are amenable.
You can start nasturtiums indoors in peat pots. Do this about a month to six weeks before the last frost arrives. Soak the seeds for a few hours to nudge germination along, but if the weather's suitable, you can skip this step and move straight to planting in the soil.
Plant the seeds with a few inches of space between them and then use a label to prevent mistaking the early growth for weeds.
Nasturtiums require well-drained, sandy, or loamy neutral soil. Plant the seeds when spring frosts are in your rearview mirror, and if you live somewhere warm, you can plant nasturtiums in fall for a lively winter. Sow seeds half an inch deep, and, within 12 days, you should see shoots emerging from the ground.
If you go the container route, nasturtiums can grow well in a 12-inch pot. Soil temperature should be approximately 55–65 degrees Fahrenheit.
These flowers need full sun, meaning at least six hours of direct sunlight daily. Partial shade conditions (three hours of direct sun) may not produce as many blooms, but the leaves may become larger. If you're growing your nasturtiums in full sun, place rocks around the plant so the roots don't overheat.
Nasturtiums can tolerate dry soil and drought, but not during the growing season. Water them deeply at least once a week, but be wary of overwatering, as disease can set in. Test the soil with your finger. If it feels dry, it's time for a drink. If not, wait for a day.
Water your plants around the roots in the morning to prevent mold from developing.
The first rule of growing nasturtiums is: do not talk about growing nasturtiums. Just kidding. You can chat about these little beauties as long as you aren't fertilizing them—these plants actually like poor soil. Soil full of nutrients will encourage the leaves to grow but not the flowers, and we all know the flowers are the endgame.
For the most part, nasturtiums are treated as annuals in the United States and Canada in USDA zones 2 to 8. Between USDA zones 9 to 11, however, nasturtiums can be planted as perennials that come back year after year.
These plants are pretty enduring. Still, the lowest temperatures they can handle are 30–40 degrees Fahrenheit.
Giving your nasturtiums a little haircut can make them tidier and encourage new growth. Prune trailing varieties in the middle of summer, or they can get leggy. Trim again by cutting off at least six inches from long stems at the end of summer. Deadhead old, browning flowers to stimulate fresh blooms.
In mounding varieties, look for dry leaves, sagging flowers, and overcrowding as signs to cut back during the summer.
Pick off flowers and leaves as required. You can eat them fresh without any prep other than rinsing. The flowers can be eaten as buds or blooms, and the leaves have a milder taste when they're new and tender. Store your pickings in water until you're ready to use them, or they'll wilt.
You can propagate nasturtiums with broken parts of the plant, including stems. Otherwise, take cuttings to foster a new lot during the spring and summer growing seasons. A three-inch section with the leaves removed can go into moist perlite and produce roots within three weeks.
Nasturtiums also root in water reasonably quickly.
Preventing diseases comes down to choosing a good spot with adequate space, sun, and water, using sterilized garden tools, and pruning. Nasturtium is fairly pathogen-averse, but it does have run-ins with botrytis blight, clubroot, aster yellows, and impatiens necrotic spot virus, for starters.
Aster yellows is incurable, and affected plants will need to be removed. Reduce disease spread by keeping the area weed-free and covered in mesh to stop leafhoppers. Prevent botrytis by avoiding overhead watering and ensuring air circulation. A fungicide can serve as a preventative measure.
Common nasturtium pests include aphids and cabbage caterpillars. You can pick the caterpillars off and hose away the aphids and whiteflies. Because the plant attracts these pests, it makes a good companion and trap crop to keep the interlopers off vegetables such as tomatoes, cucumbers, melons, and radishes.
Nasturtiums are great for gardens with a less formal feel. You can plant them along pathways—compact varieties make good edging plants and don't usually exceed 12 inches in height. Nasturtiums also look fabulous trailing from baskets or down walls. Employ a trellis for a touch of whimsy.
This species plays well with other flowers, and you can prune them to keep them from dominating an area.
Carnations, pansies, borage, and snapdragons are other edible flowers that look gorgeous atop salads or in mocktails and come in different colors. Edible flowers tend to look a lot better than they taste—nasturtiums have a strong peppery taste and are more palatable when they're young—but pansies taste like lettuce, and blue borage is cucumber-like and slightly sweet.
The blooms' colors mean that they are rich in antioxidants.
The entire nasturtium plant is edible, including stems, young seed pods, and leaves, but moderation is key. Nasturtiums are non-toxic to dogs, cats, and horses, so your pets will be safe around your floral patch.
Watercress, on the other hand, is toxic to these animals and has the scientific name Nasturtium officinale, which can often be confusing.
The genus Tropaeolum includes nearly 80 species of herbaceous flowering plants, so there are numerous nasturtium varieties. Some are annuals, some are perennials, and there are trailing and bushy varieties, plus those with variegated foliage.
If you're looking for the latter, Alaska is one such type. Black Velvet has deep red petals and yellow throats. Orchid Flames have bicolored blooms briefly, and Peach Melba looks like the inside of a peach.