Nasturtium Basic Information
Common Names: nasturtium, garden nasturtium, Indian cress
Family: Tropaeolaceae (nasturtium family)
Nasturtiums are bright and happy little flowers, that even the Grinch could not help but love. Many cultivars have been derived from Tropaeolum majus, including climbing types and dwarf, bushy types. All have rounded or kidney shaped leaves with wavy-margins. The leaves are pale green, about 2-5 in (5.1-12.7 cm) across, and are borne on long petioles like an umbrella. The flowers typically have five petals, although there are double and semi-double varieties. The flowers are about 1-2 in (2.5-5.1 cm) in diameter and come in a kaleidoscope of colors including russet, pink, yellow, orange, scarlet and crimson. A white flowered cultivar was bred in the 19th century but apparently has been lost. The five sepals are united into a cuplike calyx, and one of the sepals is modified into a nectar-bearing spur 1 in (2.5 cm) or more long. All parts of the plant have a peppery taste, similar to arugula or water cress. The Alaska Series are small, growin to 18 in (45.7 cm), bushy plants with single flowers and white mottled leaves and are sometimes classified as T. minus; the Jewel Series have double flowers; and the Gleam Series are trailing or climbing plants that can get 2-5 ft (0.6-1.5 m) long; each comes in a variety of colors. The cultivar, ‘Peach Melba’ is small, to 12 in (30.5 cm) tall, with petals that are pale yellow with orange centers; ‘Salmon Baby’ has pink flowers with fringed petals; and ‘Hermine Grasshof’ and ‘Burpeei’ have double, bright red flowers that do not produce seed; they must be propagated from stem cuttings.
Nasturtium is native to the South American Andes from Bolivia to Columbia.
Garden nasturtium does best in light, sandy soils. Too much nitrogen fertilizer will produce an abundance of foliage and few flowers.
Light: Does well in full sun or light shade. Nasturtiums appreciate a little midday shade in summer.
Moisture: Nasturtiums are fairly tolerant of drought, but do best with regular watering.
Hardiness: Plant this annual in spring in zones 4-8 and in winter in zones 9-11. Nasturtiums cannot tolerate a hard freeze, but usually will sprout back after a light frost or freeze. Nasturtiums do best with warm days and cool nights. They stop flowering in the heat of summer.
Propagation: Plant nasturtium seeds after the last frost in the garden where they will be grown, as they do not transplant well.
The dwarf, bushy nasturtiums add rainbows of cheerful color in annual beds and borders. Use the trailing forms on low fences or trellises, on a gravelly or sandy slope, or in a hanging container. Many gardeners include nasturtiums in the salad garden. Nasturtiums are attacked by aphids, and organic gardeners like to plant lots of them all around the vegetable patch to serve as aphid “lures.” Nasturtium flowers, leaves and immature seed pods have a tangy taste like water cress, and the colorful flowers really brighten up a green salad. Add some nasturtium flowers to an herb vinegar. The immature pods can be pickled. The mature seeds can be roasted for eating out of hand or used like black pepper.
Nasturtiums are perfect for introducing kids (and beginners of any age) to gardening. The seeds are very large making them easy for smaller children to manipulate. The plants germinate quickly, grow rapidly and have large showy flowers. The fact that they are edible (as opposed to toxic!) makes nasturtium the number one plant for budding gardeners.
Nasturtiums are very easy to grow and the seeds are large and easy for children to handle. They are pretty, fairly long-lasting flowers and the young gardener will be proud to make an arrangement of cut flowers or add them to the family’s salad plate.
Hummingbirds insert their long bills into nasturtium flower spurs to sip the nutritious nectar. When they do this, they get some pollen on their faces and then they do the nasturtium’s bidding by delivering the pollen to another flower.
Nasturtium Diseases and Pests
Plant Health Problems
Diseases caused by Bacteria:
Wilt, Pseudomonas solanacearum.
Infected plants yellow, wilt, and eventually die. Stems may develop black streaks and when cut, may ooze a bacterial slime from the cut ends. Roots often appear black and infected plants may die before flowering. The bacteria persist in plant debris in the soil and can infect nasturtiums through the roots.
Control strategies are aimed at prevention. However, removing and roguing of diseased plants is critical. It is also important to avoid overhead irrigation since these bacteria are easily spread in splashing water. Any equipment or tools that come in contact with diseased plants should be disinfested with 10% household bleach, 70% alcohol, or one of the commercially available compounds. Crop rotation is also effective since planting in clean soil gives best control. It is therefore helpful to avoid planting in areas used for other plants that are susceptible to the same disease, i.e., tomatoes, potatoes, eggplants, zinnias, dahlias, chrysanthemums, and marigolds.
Bacterial leaf spot, Pseudomonas sp.
Small brown to black spots appear on the leaves. These may have water-soaked margins.
This disease can be minimized by improving air circulation by thinning the plants and by avoiding overhead irrigation since these bacteria are easily spread in splashing water. Picking and destroying infected leaves and cleaning up all plant debris in the fall are also very helpful. Any equipment or tools that come in contact with diseased plants should be disinfested with 10% household bleach, 70% alcohol, or one of the commercially available compounds.
Bean aphid, Aphis fabae.
This aphid frequently infests nasturtium plants. Among the compounds registered for control of this pest in Connecticut are acephate or insecticidal soap, which can be sprayed on the insects. Imidacloprid, applied as a soil drench, will be taken up by the roots and provide season-long systemic control. Consult the label for dosage rates and safety precautions. Natural enemies, such as syrphid larvae, ladybeetles and lacewings can assist in keeping aphid populations in check.
Cabbage looper, Trichoplusia ni.
This caterpillar, which humps its back or loops when it crawls, feeds on leaves. It is light green and striped lengthwise with white and darker green. Its body is nearly smooth and is narrowest at the head. The adult is a grayish-brown moth with a small silvery spot resembling a figure 8, near the middle of each forewing. It flies at night when it deposits small round greenish-white eggs, singly, on the leaf surface. This species does not overwinter in Connecticut, but migrates up from the south in some years. Among the compounds registered for control of this pest in Connecticut are spinosad, Bacillus thuringiensis var. kurstaki (Bt), Bt var. aizawai, and carbaryl. A high rate of Bt may be needed and will be more effective when both the days and nights are warm. For either insecticide, consult the label for dosage rates and safety precautions.
Corn earworm, Helicoverpa zea.
The moths, with a wingspread of about 1.5″, are tan with darker markings. They arrive in Connecticut each season from more southern areas after which they lay eggs singly on leaves. After hatching, the caterpillars feed, eventually reaching a length of up to 2″. They vary greatly in color from brown, tan, green, or pink with light and dark longitudinal stripes. The head is golden brown and the body has small bumps and spines, giving it a rough texture. There can be two or three generations in a year, depending on when the adults arrive on winds from the south.
Spinosad and Bacillus thuringiensis var. kurstaki (Bt) are registered for control of this pest in Connecticut. Consult the label for dosage rates and safety precautions.
Serpentine leafminer, Liriomyza pusilla.
The larva of this fly makes a serpentine mine in the leaf of nasturtium. The turnip leafminer and the columbine leafminer (see Columbine) have been recorded as occasionally infesting nasturtium. Usually, no control is necessary. Among the compounds registered for control of this pest in Connecticut are acephate sprayed on the foliage or soil treatment with imidacloprid. Abamectin is an effective restricted use product. Consult the labels for dosage rates and safety precautions.
Western black flea beetle, Phyllotreta pusilla.
The small black beetles make small holes in the leaves, and jump readily when disturbed. Among the compounds registered for control of this pest in Connecticut are acephate or carbaryl used as foliar sprays. Consult the labels for dosage rates and safety precautions.
How To Grow Nasturtiums
STEP 1: Check out nurseries for seedlings. Most greenhouses carry them.
STEP 2: Read labels carefully. Some nasturtiums climb like a vine while others sprawl like a groundcover. Some have plain green leaves while others have leaves with fancy green or light cream markings. Flower colors also vary from cream to rich reds, yellows and golds.
STEP 3: Plant seedlings in loose, well-drained soil that also is moisture-retentive. (They don’t do well in heavy clay, for example.)
STEP 4: Plant seeds outdoors, 12 inches or more apart and about 1/4-inch deep, about one week after your region’s last frost date.
STEP 5: Keep soil moist but not soggy.
STEP 6: Check regularly for aphids, which appear as tiny white blobs on stems and underneath leaves. If they occur, treat immediately with an insecticidal soap – an earth-friendly pest control method.
STEP 7: Pull up and discard plants in autumn, once frost has felled the plants.
Tips & Warnings
- Nasturtiums are happiest in full sun (with a little afternoon shade in the South) in average, well-drained soil.
- Nasturtium flower petals are edible. Pluck a few and sprinkle over your next salad.
- Nasturtiums don’t like too much fertilizer or soil that’s too rich. In these conditions, they’ll produce lots of lush growth but few flowers.
A Brief History of Nasturtiums
Colorful, edible, butterfly-like nasturtium blossoms have delighted gardeners and cooks alike for centuries. At different times in their history, they’ve been considered a vegetable, an herb, a flower, and even a fruit! The name nasturtium comes from the Latin words for nose (nas), and tortum (twist), referring to a persons’ reaction upon tasting the spicy, bittersweet leaves. Renaissance botanists named it after watercress, (Nasturtium officinale in Latin) which tastes similar.
The garden nasturtiums we grow today descend mainly from 2 species native to Peru. The first, brought to Europe by Spanish conquistadors in the late 15th to early 16th century, was Tropaeolum minus, a semi-trailing vine bearing spurred, lightly scented orange-yellow flowers with dark red spots on the petals and shield-shaped leaves. According to Jesuit missionaries, the Incas used nasturtiums as a salad vegetable and as a medicinal herb. In the late 17th century, a Dutch botanist introduced the taller, more vigorous Tropaeolum majus, a trailing vine with darker orange flowers and more rounded leaves. Since Spanish and Dutch herbalists shared seeds with their counterparts, the pretty, fragrant and easy-to-grow plants quickly became widespread throughout around Europe and Britain.
Nasturtiums were commonly known in Europe as Indian Cress or a translation of “Capucine cress”, in reference to the flower shape, which resembles Capucine monks’ hooded robes. Leaves of both species were eaten in salads; unripe seeds and flower buds were pickled and served as a substitute for capers. (We know now that these pickled flower buds are high in oxalic acid and therefore should not be eaten in large quantities.)
Their ornamental value was also appreciated: flowers were used in nosegays, and planted to adorn trellises or cascade down stone walls. They became especially popular after being displayed in the palace flowerbeds of French king Louis XIV.
Although it is sometimes reported that nasturtiums were introduced to the US by the Philadelphia seedsman Bernard McMahon in 1806, they were recorded here as early as 1759. Thomas Jefferson planted them in his vegetable garden at Monticello from at least 1774 onward. Interestingly, in one entry in his garden book, he categorized it as a fruit amongst others such as the tomato, indicating that he ate the pickled seeds. Most nasturtiums grown at this time were the tall, trailing orange variety.Over the course of the 19th century, breeders produced smaller, more compact types that mounded neatly into containers or formed a colorful, less sprawling edge to flower beds. Cultivars with cream and green variegated foliage appeared, as well as the vermilion-flowered Empress of India, with its strikingly contrasting blue-green leaves. These developments paralleled the gradual shift in the perception of nasturtiums from edible and herbal garden mainstays to viewing them as ornamental landscape plants. Monet let large swaths ramble along a walk at Giverny. The flowers and long-lasting leaves were popular in Victorian bouquets and table arrangements. Nasturtiums were still eaten, however, and were known to help prevent scurvy, since the leaves are rich in Vitamin C.
Later 20th century contributions to nasturtium breeding include the introduction of varieties with spurless, upward-facing blossoms and flowers that float higher above the leaves, perfect for bedding or containers. A full spectrum of flower colors is now available, including single colors—useful for landscape designs: pale yellow, golden, orange, brick-red, cherry pink, salmon, crimson, and dark mahogany. The recent interest in edible flowers, herbs, ornamental kitchen gardens and heirloom flowers has helped keep a full array of old and new cultivars available for every possible use.
Welcome to Nasturtiums
This past week I have developed numerous other sites on flowers. I have chosen some of my very favorite ones…ones that I have grown for many years as an active gardener.
Another native of the Americas, nasturtiums have been cultivated for centuries and are almost the perfect garden flower. Not only do they provide endless and brillant color to the garden, but act as a deterrant to many garden pests and finally, they are edible. You can add them to salads, use them as herbs and as a spice.