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growing nasturtium from seed

Black Thumb? Bored Kids? Junky Yard? You Need Nasturtium Seeds!

Someday, we're going to organize a seed collection based solely on the need for low-maintenance plants that flourish in poor soils, tolerate neglect, and make a junkyard look like a topiary garden. Nasturtium would be the flagship species, and while we have a short list of names for this variety pack, we're open to suggestions.

Nasturtium's also a fantastic candidate for a kid's garden, and while we encourage grown-ups to introduce their children to the art of growing plants for the sake of engaging them with nature, we won't lie to you: child labor is a huge asset to yard work.

Tropaeolium's large, easy-to-handle seeds, its quick growth, edibility, and multi-purpose characteristics enthrall gardeners of all ages and abilities with the added benefit of it being flat-out gorgeous. We're confident you'll find all sorts of ways to incorporate nasturtium into your garden, whether you use it to cover unsightly walls, to cascade from container gardens, or cover up the crumbling play equipment your kids haven't used since you decided to turn growing all your own food into a family project.

Nomenclature, origins, and history

The name "nasturtium" is actually a reference to an entirely different genus, Nasturtium officinale—otherwise known as watercress. Both have leaves with the same crisp, spicy flavor, though watercress is a member of the Brassicaceae tribe while the Tropaeolium genus hogs the entire Tropaeolaceae family.

Wouldn't you think that nasturtium would qualify for its own unique common name? We do. There are about 80 classified Tropaeolium species, after all. Nasturtium are native to South America, specifically Peru and Chile and the Andean foothills. Spanish physician and botanist Nicolás Monardes (for whom our beloved bee balm is named, and who lived from 1493 to 1588) brought it to Europe where it was first referred to as Indian cress. The New World, after all, was the "Indies" back in the day. Tropaeolium quickly naturalized in many parts of Europe, and may only have reached the eastern United States when the early colonists brought it over.

"Nasturtium" is derived from the Greek nasus tortus, or "twisted nose." Some think this refers to the plant's odor, while others consider it a nod to watercress' use as a decongestant. Crushed watercress certainly tweaks the nostrils, but this nasturtium has only a faint, pleasant fragrance.

The nasturtium (from here on out, "nasturtium" refers to Tropaeolium. Watercress already had its 15 seconds of fame on our blog.) family's botanical name makes up for its hand-me-down common name. Botanist Carl Linnaeus (1707-1778) came up with Tropaeolaceae after comparing the plant's round leaves to shields, and the deep orange-to-red trumpet-shaped flowers to helmets. Ancient Romans would hang armor and other... items belonging to their defeated opponents on stumps, poles, and trees, and called these "victory monuments" or tropaion. The Anglican translation? "Trophy." Think of this when you're planning your next bowling tournament awards ceremony.

Medicinal and culinary uses

Plants for a Future reports that Tropaeolium majus, the most commonly cultivated nasturtium species, has a long history as a medicinal herb in Andean cultures. They attribute the following properties to nasturtium, with the note that extracts from the plant are being explored as a cancer-fighting compounds.

  • antibacterial
  • antifungal
  • antiseptic
  • depurative (that means "antioxidant")
  • diuretic
  • emmenagogue (aids the menstrual process—weird name for that, right?)
  • expectorant
  • laxative
  • stimulant

All members of the Tropaeolaceae family are edible. You've likely munched the leaves and flowers in salads, or have seen the blossoms decorating wedding cakes. (Do the brides know about the whole Roman trophy thing?) As mentioned, both the flowers and the leaves have a crisp, fresh, mildly spicy flavor, and fresh nasturtium seed pods have a more concentrated kick. Nasturtium leaves are best when harvested in the morning. Cut the stems with the flowers and keep them refrigerated in a glass of water. You can do the same with the leaves, or store them as you would other tender salad greens. Try them fresh, sauteed, or stir-fried; we enjoy them with a little lemon and garlic.

Nasturtium seeds produce oil, which has been pressed (pun intended) into service both medicinally and artistically. Its quick-drying nature allows it to be an ideal carrier for pigments.

Nasturtium in the garden

Tropaeolium are vining plants that can climb up to 12' in height or reach a spread of five feet or more in diameter. Sprawling nasturtium keeps a low profile, rarely popping up more than 12" to 18" above the ground. While we'd grow it for its leaves alone, its bright and cheerful flowers bloom from May until the first fall frost.

The fringe-flowered T. peregrinum is an example of the small group of nasturtiums having deeply-lobed foliage, but the most common nasturtium species bear leaves that are gently scalloped in the developing phase, becoming nearly perfectly round when they're mature. Nasturtium leaves are peltate, meaning that the stems connect to the leaves in the center of their undersides. This feature lends visual dimension to the plant and contributes to its airy, layered appearance. The purpose of this leaf type is to allow the stem to rotate, better positioning the foliage to capture sunlight. The leaves' pale veins radiate outward from a light-colored center, and their surfaces can be smooth or slightly crumpled. They usually have a soft, glowing, matte appearance.

Nasturtium flowers are trumpet-shaped, with downward-pointing spurs that might have reinforced the association with classical age war helmets. These spurs are hollow and contain the nectar that attracts long-tongued insects and hummingbirds.

The two uppermost petals on the five-petaled flowers are a little stubbier than those below. Nasturtium blooms have a slightly wrinkled satin texture, and like their leaves, they pull all the stops when it comes to vivid color. Nasturtium blossoms may be cream, yellow, orange, red, or burgundy, and bi-colored flowers aren't unusual.

The ideal spot for nasturtium

Nasturtium is technically an herbaceous perennial, but it's grown as an annual in USDA hardiness zones 2 to 11. They may experience fall die-off and spring regrowth in zones 9 through 11. Nasturtium grows quickly from seed, reaching the flowering stage in as few as 30 days, so if you're in a colder zone and forget to insulate the root area during a hard frost, you can start over the spring: Nasturtium is the perfect "Mulligan" plant.

How does such a beautiful plant thrive in such crappy soil? Nasturtiums are wonderful plants for sandy, low-nutrient garden areas. We never thought this phrase would come out of our mouths, but sometimes richness is a bad thing. Overloading nasturtium with nitrogen triggers more foliar growth while limiting flower production. We recommend well-drained soil, with just enough aged compost mixed in to break up compacted beds. The best pH for nasturtium is between 6.1-7.8.

Tropaeolium requires full sun in its native cool climates, but they like a spot with light afternoon shade in the hottest, most arid regions. It tolerates some drought but does best with consistent moisture. Water them deeply but don't subject them to soggy or heavy soils.

For climbers, you'll want to provide support. You might need to secure the vine-like stems to walls and trellises. Spreading nasturtium will fill in gaps around mature plants, and depending on how well they thrive, you might need to trim them back to keep them in line.

Nasturtium is a fantastic plant for hanging containers, and it cascades nicely from retaining walls. You might want to choose a dwarf variety for pots or baskets, but standard species will do fine provided they're given ample water.

Nasturtium as a weapon against garden pests

We've heard nasturtium erroneously referred to as a garden pest repellent, but in fact the plant attracts many harmful pests. It's more accurate to call nasturtium a bug-trapping species, since it can draw critters away from other ornamentals and vegetables. The theory is that affected nasturtium leaves and flowers are far easier to trim and destroy, and it grows quickly and vigorously.

Since nasturtium thrives beautifully in the Golden State's coastal regions, we turned to University of California's Agriculture and Natural Resources department to learn more about pests and diseases associated with the Tropaeolaceae family. According to them, these issues are common to nasturtium:

  • Cucumber mosaic virus
  • Nasturtium mosaic virus
  • Tomato spotted wilt virus
  • Turnip mosaic virus

They also warn that caterpillars, cabbage worms, spider mites, and whiteflies target nasturtium, so if you want to experiment with plantings in and around your veggies, let us know how it works for you! In our experience, nasturtium plants are no shrinking violets, so even if they do get hit with the nasties, they seem to handle it well.

Growing nasturtium from seed

Nasturtium seeds have a tough hull and need a little help to encourage germination. Direct-sow nasturtium in the fall in colder regions to take advantage of the spring/thaw natural stratification process. For spring planting, we recommend a 1 to 3 month cold stratification period or a 24-hour soak at room temperature (starting with hot water). Since the seeds are relatively large and easy to handle, you might want to give them a pass or two with an Emory board. For more information on pre-treating seeds, check out our article "The Dirt on Successful Seed Germination."

  • When to Plant Outdoors: Wait until all danger of frost has passed for direct-sowing in the spring.
  • When to Plant Indoors: Start your nasturtium seeds indoors 6 to 8 weeks prior to the last frost. Once the seedlings emerge, put them under artificial light until they've grown 3 to 4 true leaves. Use peat pots to reduce transplanting shock; nasturtium has a sensitive, fast-growing taproot.
  • Seed Depth: 1/4" inch deep or twice the length of the seed's shortest dimension.
  • Seed Spacing: Thin or plant at least 18" apart. They'll quickly cover any open spaces.
  • Days to Germination: 14 to 30 days at 65°F. Sometimes they'll surprise you after a single week if they're properly prepped.

When growing nasturtium from seed, be sure to plant your nasturtium seeds in beds free of clumps and organic debris. Unlike many other ornamentals, they need darkness to germinate, so we don't recommend scatter-bombing them willy-nilly. You can harvest the seeds at the end of each season once the pods dry, or let them reseed themselves in situ, but unless the seeds work themselves under the surface, they'll either fail to start or become a treat for neighborhood birds.

Seed Needs: We're (mostly) kidding about the child labor thing

We started selling fresh non-GMO seeds in 2006, but we're still a small, family-run business dedicated to quality products and customer service. And no, in spite of our previous jokes, we don't chain our kids to sorting tables. Their most important role here at Seed Needs is inspiring us to help your gardens reach their fullest potential, and to give back by lending a hand to 25 international families and their communities through and Compassion International.

If you have any questions about our products—whether you're planning a purchase or received an order—please let us know! And if you have any ideas for our proposed collection of seeds for lazy/drunk/transmission hoarding gardeners, we'd certainly appreciate your input.
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