DIY Green Manure: Growing Clover From Seed

Are you looking for a plant that's easy to grow, blooms with spectacular flowers, and improves your garden's soil?

You might think of clover as the low-growing, white-blossomed garden party crasher that photobombs your picture-perfect lawn. Or maybe you're reminded of Saint Patrick's Day, which in turn reminds you to crack open and enjoy that Guinness before the kids get home from school.

If you're savvy, you might think of huge swaths of red or purple flowers blanketing farm fields as they rest in between crops of organic produce.

There is a wide variety of clovers, from species sown as cover crops and high-protein pasture plants to those cultivated primarily for ornamental use. All of them improve soil quality through nitrogen fixation and biomass production, and most of them double as stunning ornamentals.

Clover + Rhizobia = Healthy Soil

Clovers are legumes, and like lupines, beans, and peas, they accumulate nitrogen from the air and through their roots. As the plants break down and decay, they release nutrients back into the soil. In this scenario, especially when they're cultivated into the soil, clover makes a very effective green manure.

Legumes don't have to wait until they're dead and buried to help the soil biome (dirt nerd link!). Especially when they're inoculated with rhizobia, legumes positively affect the root structures and nutrient uptake of surrounding plants.

By now, you probably know the importance of maintaining healthy fungal and bacterial communities in your soil. These living materials help break down nutrients to allow for better nutrient absorption, and they help the soil retain its moisture and texture. The "no-till" agricultural movement is a response to topsoil loss and soil "death" caused by the constant disruption of soil organisms, which in turn contribute to desiccated, low-nutrient topsoil.

Dust Bowl, anyone? Grapes of Wrath, in case you didn't know, wasn't about getting drunk on box wine and complaining about potato worms.

Clover's role as a cover crop also allows farmers to plant quick-growing biomass in between grain rotations to keep topsoil from eroding through heavy rains or blowing wind.

Check out this adorable video produced by the Queensland Government (talk about "on the nose!") about rainfall, erosion, and cover crops.

Clovers grow quickly, and they're mowed to mulch and shield fallow fields from weed growth and the elements. Dense planting crowds out unwanted plants. Low-till operations can scale back on disking (essentially turning over the earth) and severely reduce their herbicide applications. Nitrogen fixation reduces or eliminates the need for chemical fertilizers.

Graziers—a fancy name for ranchers who manage pastures to feed their livestock—plant combinations of legumes and cereal grains to maintain a balance in both their soil health and their animals' nutrition. Just as vegetable and grain growers rotate their fields, savvy graziers rotate their pastures to allow for recovery and rejuvenation, and both use legumes like red, crimson, and mammoth clovers either as a temporary monocrop, or interspersed with other species.

Clover in the Garden

"What the...Don't waste my time! I don't live on a freaking farm. How is clover useful to me?" We're glad you asked. Even urban gardeners can benefit from planting clover. It's a graceful and colorful ornamental, it's easy to manage, and it doesn't require a tractor-pulled drill seeder to plant. Clover's an important nectar source for honeybees and other pollinators, and it makes a gorgeous cut flower.

Depending on the species, clover might grow closer to the ground, or up to waist-height. It's flower heads might be round, or they might be spiky. Since we're painting with broad strokes, we'll use two of our favorite types of clover to best describe their general appearance and behavior in the garden.

Crimson clover (Trifolium incarnatum)

Even though crimson clover performs on an industrial agricultural scale, it very much fits the "dainty flower" bill...though, uh, its flower color is harlot red.

• T. incarnatum is an annual in USDA Zones 5 to 9. In zones 1 to 4, it's been known to survive through winter.
• It's native to southeastern Europe and southwestern Asia Minor and was introduced to the United States as a cultivated crop in the 1800's, according to the USDA.
• It prefers cool weather, and it's best grown in early spring or, in areas with late frosts, in the fall.
• In the coldest zones, grow it in midsummer but be prepared to irrigate.
• Crimson clover prefers moist, well-drained soils.
• Fall frost kills crimson clover, leaving a high-nutrient mulch to decay over the winter. Looks bad, but hey.
• Speaking of hay, crimson clover makes great standing browse or, when dried, a nutritious winter feed for your dairy goats. (Yep. We're back on the goat kick again!) Here's a good time to note that too much white clover can cause animals to bloat.

Crimson clover grows 1 to 3 feet tall, with dark green clover-shaped (duh) leaves. The plants are upright, on one to four stems diverging from a single root ball. Their oblong 1" to 2.5" flower heads, growing at the top of the leafy stems, tend to resemble tiny bottle brushes. Their oval shape separates T. incarnatum from the pointier red and mammoth clovers.

Purple Prairie Clover (Dalea purpurea)

Purple prairie clover (also simply called prairie clover) is a perennial species that handles warmer, drier summers. It has a deeper taproot (up to six feet!) than crimson clover, allowing it to thrive in drier conditions. Its ideal growing zones are 3 to 8, and it prefers inland regions over cool, coastal environments.

Purple prairie clover flower heads are dense green oblong shapes from which purple florets bloom in successive rings along the heads in a pattern similar to French lavender...but with smaller and lighter blossoms.

That's not the only resemblance between these two plants. Purple prairie clover has a clumping base, and instead of the trademark three-lobed foliage we expect from clovers, its leaves are needle-like, emerging from whorls along the plant's tall stems.

It handles drier soils than red clovers, and it's native to central North America. Its high protein content makes it an important browse for wild ruminants and ungulates, and like crimson clover, it's a valued pasture plant, particularly for sheep and goats.

Big surprise, but Dalea purpurea isn't a true clover. It's still a legume, though, and it's taproot and sub-surface root structure make purple prairie clover an ideal plant for erosion control. This taproot also brings nutrients to the above ground plant structure, increasing its value as a green manure and forage plant.

Purple prairie clover grows 10" to 3' tall, with oval 1" to 2.5" flower heads.

General Cultivation Recommendations

These are general guidelines for growing clover from seed. Be sure to refer to your seed packets for specific information!

Sunlight Preferences: Clover requires full sun.

Moisture Requirements: Most clovers thrive best in moist soils, and can handle a little drought...especially purple prairie clover.

Soil Preferences: Clover is adaptable to poor soils, as long as there's sufficient drainage. In fact, rich soils and added fertilizer don't really boost clover growth, but it sure supports weeds and volunteer grasses! Recommended pH is between 6.5 and 7.5.

Pests & Diseases: Alfalfa weevils, leaf rot, and mosaic disease; clovers might harbor different types of thrips.

Harvesting: Mow it, pick it for cut flowers, or dry it upside-down in an arid, well-circulated area.

General Tips for Growing Clover from Seed

You've got a few options for clover seed planting techniques. Early spring seeding works great if you get a hard frost or two before the soil warms up; simply scatter the seed on the soil surface. Frost heave will work the seeds into the soil, possibly cracking the outer layers, readying them for when the soil warms up.

Or, grab a hand-spreader, mix your seeds with some sand, and broadcast your seeds onto the soil's surface (a light raking helps) right after your last frost. This timing and method works best for purple prairie clover and other warm-season perennial clover species.

Avoid covering clover seed with more than 1/4" of soil.

Unless you're "frost seeding," keep the soil moist with a sprinkler, or plant when there's a good chance rainfall will keep the soil nice and damp.

Seed Treatment: No stratification is necessary, but you'll want to consider inoculating your clover seeds for the best nitrogen production. In most healthy garden soils, there are enough rhizobia to optimize nitrogen fixation. If you're planning on strafing a long-barren area with clover seeds, you might want to pick up some inoculant from your local big box store or garden department. (There are different bacteria for different plants, so read the packet to choose the one right for your clover variety.)

When to Plant Outdoors: Early spring (after the last frost) for late fall for cool-season clovers, or late spring or early summer for heat-tolerant species.

Days to Germination: Warm season clovers planted when the soil temperatures hover around 70°F to 75°F can germinate as soon as 5 days after planting, while cool season types might take a week or two to get out of the gate.

Thinning or Spacing: Just let 'em duke it out!

Clover's Notable Edible and Medicinal Uses

Clover is pet safe and kid-friendly. You can make tea out of dry crimson clover heads (as well as from other "red" varieties) and tender leaves and shoots from true clovers add interest and flavor to salad greens.

Anecdotal evidence implies that infusions from red clover (which is actually lavender in color) may treat cancer, and is used to reduce whooping cough symptoms and other bronchial disorders. We've found reports that crimson clover shares the same attributes.

Sourcing Your Clover Seeds from Seed Needs

There's no reason to go to your local farm supply store to buy fifty-pound sacks of clover seed when you're on a residential lot. We fulfill requests for custom quantities, and if you're just looking for a permanent clover patch, a little goes a long way; clover easily reseeds on its own.

Since we've discussed industrial ag, we'd like to tell you that our clover seeds—and the rest of our vegetable, herb, and ornamental products—are non-GMO and, whenever possible, obtained from organic stock.