Simple Summer Buckwheat: Fast, friendly, and fresh summer soil food for the short gap to build long-lasting soil health

At last, summer has arrived! Gardens overflow and our hands are happily busy weeding, seeding, harvesting spring veggies, and prepping for fall. If you are like me, the  garden schedule, carefully planned out over months of winter dreaming, has vanished in a flurry of berries to pick, compost to turn, and tomatoes to trellis. Even though precious garden hours and space may seem full, there is always time and a place to plant a quick-growing summer green manure.

Young lush buckwheat green manure.
A young buckwheat green manure ready to be turned into the soil.

In fact, there is no better time than the full-blown growing season to catch the energy of the sun and turn it into soil organic matter.This is where buckwheat cover crop comes in. It grows fast enough that I can spread some seeds without any advanced planning. If I kill it early enough, it rarely competes with other garden plants. With soft, succulent foliage and shallow roots, pulling it up and using it to amend the soil is hardly work at all.

The versatility of buckwheat means that I can plant it whenever there is a gap in my garden. This can be a gap in time – the few weeks between harvesting spring veggies and planting fall ones. Or a gap in garden cover – buckwheat can go between rows or can be interplanted with other vegetables, like winter squash, to cover ground while they get established. In reality, I can throw down some buckwheat seeds whenever I see bare soil, without much long-term planning. Because bare soil is a missed opportunity for building soil and supporting the living soil-garden system, buckwheat gives me a chance turn short-term garden growing gaps into long-term soil food. In the process, I save time and energy by taking advantage of a garden that grows its own amendments with green manure cover crops. 

How-to cover crop with summer buckwheat

Timing (Quick): Buckwheat takes 70-90 days from seed to bloom, but it can give great green manure benefits in as little as 40 days. This is fast enough that I can even fit it into the window between early and late spring veggies, if I seed it into the last of the peas and weed it out as late spring transplants establish. For longer fallow periods between spring and fall, use buckwheat in 2 or 3 successive plantings or mowings. Over the years I have found that I always have more time than I think for  a quick buckwheat cover. My motto: when in doubt, throw the seed out.

Planting: Buckwheat is a frost-sensitive warm- to cool-season forb. Plant after the danger of frost has passed. In warmer regions, buckwheat can establish as a late winter cover crop. In Oregon, my first sowings are in late April-May. Buckwheat puts on vigorous growth throughout the high summer, but it does slow down in September.

Buckwheat has large seeds that germinate in as little as 1-3 days. Broadcast and scratch into the surface of a clean garden bed at a rate of 2-3 pounds per 1000 square feet. If oversowing into the end of late spring or summer vegetables, seed at a higher rate. Keep soils moist until germination.

Although it can thrive in low fertility soils or soils with lots of decaying organic matter, buckwheat does have some problems with heavy clays or compacted soils. It is also sensitive to drought, so is not be a good option in very hot an dry regions or areas without summer irrigation.

Killing: Kill buckwheat before it goes to seed. To maximize soil organic matter, pull or turn under as it begins to flower. If short on time, pull buckwheat in as little as four weeks to still see soil building benefits. To maximize the pollinator benefit of buckwheat, let it flower for a week or two but avoid letting buckwheat go to seed, unless you don’t mind it coming up next season.

Buckwheat is one of the easiest cover crops to incorporate into the soil. If prepping for the next round of garden crops, simply chop buckwheat into garden beds with a light spading. Buckwheat breaks down quickly in the soil, but it is still best to give it a week or so before planting.

Here’s a quick video tutorial from Sow Seeds in Britain showing how-to digging buckwheat in the garden. So easy!

Alternatively, pull buckwheat up by the roots, or cut it at ground level, and mulch it right on the soil surface. I do this on my no-till beds or when I have interplanted buckwheat with other crops. Pull the buckwheat mulch back while smaller seeded plants get established, and then use as a garden mulch. For maximum soil-building, add another brown layer – straw, leaves, or compost – on top of the green buckwheat when mulching.

With mowing, a single buckwheat sowing can also yield 2 or 3 successive crops. If mown before 25% of bloom, buckwheat will come back from the roots, doubling or tripling organic matter production in a season.

Buckwheat benefits

Like any important piece of the whole garden puzzle, the benefits of buckwheat are multifold. While it builds organic matter in the soil and provides a living feast for soil organisms, it also has other unique benefits for the whole garden ecosystem.

Weed control: Dense, fast-growing buckwheat is great for smothering unwanted weeds, another great reason to use it to cover bare, fallow ground. Because of this, it can also be used as a nurse crop to protect and suppress weeds for slow to establish winter legumes or a as an intercrop to provide a living mulch for corn or squash.

Pollinators and Beneficials: Buckwheat’s pretty white summer flowers also attract and provide nectar for pollinators and beneficial insects, like hover flies and lady beetles.

To get the most bang from your pollinator bank, seed buckwheat in a flower-power guild with phacelia or mustard.

Buckwheat, Fagopyrum esculentum, in flower.
Buckwheat, Fagopyrum esculentum, in flower

Phosphorous: Not only does buckwheat add organic matter, it enriches and fertilizes soil with phosphorous as well. Buckwheat, like many cover crops, can scavenge and pull up phosphorous from the soil into more plant-friendly forms.

Conditions the Soil: Buckwheat is small, but mighty. It does not have the massive root-drilling power of daikon radish cover crop, but its many, tiny roots pump out delicious soil food. All the growth and organic matter that decomposes from root lightens and loosens soils in as little as a season.

 

More Buckwheat Resources

Buckwheat information from SARE’s Managing Cover Crops Profitably

A nice article about the beneficial insect and weed suppression advantages of buckwheat From Growveg.com

A whole handbook on buckwheat cover cropping from Cornell Extension

Homegrown Humus: Cover Crops in a No-Till Garden by Anna Hess (e-book)

More about multiple buckwheat uses from Temperate Climate Permaculture

Soba: Japanese Buckwheat Noodles

Alternative Crops: Growing Buckwheat for Grain

Buckwheat Green Manure: Fill the Summer Gap to Build Soils Fast
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