cover image by Mary Martin; USFWS

We had just harvested all of our main crops - boxes of winter squash were piled in the living room, bags of tomatoes were stored in the freezer waiting to be turned into sauce, and the last of the peppers and zucchini lined the kitchen counter.

It was the evening before our first frost of the season, but I wasn't done growing crops in the garden. I had a plan to renew our garden beds and greenhouse with a powerhouse of a crop that I wouldn't harvest to eat. Instead, it would serve as a defence from disease and erosion, be a natural nitrogen fertilizer, and store some extra carbon in the soil during an otherwise dormant season.

What the heck am I going on about?

It can only be the hero of cover crops: hairy vetch.

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What is Hairy Vetch?

Hairy Vetch | Vicia villosa | Legume

Optimal Sowing: Shoulder seasons; favoring autumn

Ideal Germination Temp: 60°F

Max Height: Up to 12 feet when vine-supported; typically 3 feet as a cover crop.

Germination Time: 14 Days

Cold Hardiness: to zone 4; zone 3 with snow insulation

Bloom Time: May-August (Northern Hemisphere)

(advance cover crops, sustainable agriculture research and education, USDA NRCS)

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Continue on to understand why hairy vetch stands out as a premier cover crop in the world of regenerative gardening.

The Role of Cover Crops in Agriculture:

→ Cover Crop Definition: A crop that adds benefits to the soil. Soil with active crops is more protected than bare soil.

Growing crops benefits the environment, since they sequester carbon with photosynthesis.

Cover crops also benefit the health of the soil and can provide nutrients that the next crop can access.

Let’s first look at why cover crops are important. Then, we’ll dive into the specifics of hairy vetch.

Cover crops are a core component of regenerative gardening. The practice of planting cover crops was popularized due to the work and advocacy of George Washington Carver.

Cover crops offer carbon storage and benefit soil health. Both of these results are the main goals of regenerative agriculture.

In contrast, bare soil releases carbon and is at-risk for erosion and nutrient loss.

Cover crops help the environment by capturing carbon from the air and storing it in the soil.

Cover crops in general offer the following additional benefits to your garden:

• reduce soil erosion
• improve water retention
• add organic matter to soil
• can be used as a mulch
• reduce weed pressure
• add nutrients to the soil that are available for the next crop
• attract beneficial insects through habitat and food source

Growing Hairy Vetch in Your Garden as a Cover Crop

Now that you understand the benefits of cover crops, let’s look at the specifics of hairy vetch.

The scientific name for hairy vetch is Vicia villosa.

Vicia is the botanical Latin term for the Vetch genus.

Villosa means hairy in Latin.

As a member of the legume family, hairy vetch forms a symbiotic alliance with soil microbes. This collaboration fosters the transformation of atmospheric nitrogen into a form that nourishes the soil and future crops (USDA NRCS).

What are the optimal growing conditions for hairy vetch?

Hairy vetch likes to be grown in the shoulder seasons, and its typically sown in the fall.

Ideally, temperatures will still reach 60 degrees during this time for optimal germination.

In my own experience, this temperature mark is crucial. This past autumn, by the time I had cleared out all of my crops, we already had our first frost. I heavily scattered hairy vetch seed in rows outside and also inside my greenhouse.

I think the temperatures outside werren't ideal, as germination was quite low there. In contrast, the seeds in the greenhouse germinated well and soon formed a lovely carpet of hairy vetch seedlings before winter really set in.

Once germination occurs, hairy vetch is very cold hardy. Without any addtional support, it will survive through zone 4 winters. It can survive under snow cover in zone 3, too (SARE).

I found hairy vetch to be very easy to maintain in the greenhouse - it required little watering and mostly took care of itself there.

What does hairy vetch look like?

Hairy vetch has small oval leaves that are opposite each other, with a tiny point at the end. Hairy vetch has beautiful purple flowers if it blooms. They magnet for bees and other pollinators.

Hairy vetch is vining, and like peas has thin curling tendrils that help it to climb in height.

According to Sustainable Agriculture Research and Education, hairy vetch can grow up to 12 feet tall! This is only if its able to climb up tall grasses, however.

If that feels like an overwhelming height, don’t worry. When grown on its own, this cover crop usually maxes out at 3 feet tall.

When does hairy vetch bloom?

Usually the flowers come on between May-August in the Northern Hemisphere (USDA NRCS).

When to cut back a hairy vetch cover crop?

Early in the bloom stage is the best time to cut back your hairy vetch cover crop, according to the Marion County Soil and Water Conservation District. This provides a food source for insects, but also reduces grow-back in the cover crop.

Hairy Vetch Planting Guide + Lifecycle

A stype by step timeline for best results with your hairy vetch cover crop.

If you get the timing right and have regular rain from autumn through spring, hairy vetch will be relatively easy to maintain.

Autumn

Looking for an autumn project for your garden? Why not consider planting hairy vetch this season?

The toughest thing might be sowing hairy vetch when daytime temperatures will reach 60 degrees F. That's the optimal germination temperature. You may be able to place a row cover over areas of your garden to help achieve this warmth level.

Soil Preparation

For best results, make sure that your soil is free of weeds before broadcasting the vetch seed.

You'll want to make sure that the soil stays moist before germination. Then, keep the crop watered regularly as it gets established.

Moderate temperatures in autumn let hairy vetch put on a few inches of quick growth.

Winter

Maintaining Your Crop

In the wintertime, the plant goes dormant. If you do not get rain in the winter, you'll need to water your cover crop around once a week or so.

Don't worry about cold weather or snow for the most part. Hairy vetch will survive winters in zone 4 with no cover at all. In zone 3, snow cover is needed to act as insulation for the crop's survival (SARE).

Spring

Warm weather and more daylight provide vetch with the energy for some intense rapid growth. This is when the vetch will form a thick mat of green material to block out weed growth.

Depending on your sowing date and spring weather, hairy vetch can bloom as early as May. For optimal mulch material and nitrogen fixation, cut back the crop as the flowers are maturing.

This will also help your first cut-back of the crop to be successful and prevent regrowth.

How to cut back hairy vetch

When it's time to cut the hairy vetch back in spring, it's pretty satisfying. Those thick mats of green chop down easily, and you're left with this great mulch that's basically free and already in place.

Let the plant residue remain to cover the soil as much as possible. If you're planting seedlings into this area, simply create a small hole in the vetch residue. Plant the seedling as normal, and leave an inch or two of exposed soil around it until it gets more established.

If you are sowing seeds directly into the soil, move the vetch mulch aside until plants are established. Then, cover any bare soil with the vetch material.

→ Important Note: Kill back cover crops in a sustainable way to keep your garden regenerative. Do not use herbicides to terminate your cover crops.

Instead, cut back the crop and leave the greenery on the soil. The residue acts as a mulch for the next crop.

You can also terminate a cover crop with a fence post like this. Alternatively, trim it back to the soil with some clippers or scissors.

Hairy Vetch’s Many Benefits

Have you ever thought about how a simple plant could improve your garden's soil and environment?

After working with hairy vetch, you can really tell the difference in the soil. It's like giving your garden a spa treatment—everything's just better afterwards. The soil's loamy, and you can almost hear the worms and bugs thanking you. I actually noticed more worms and soil critters after a season of growing hairy vetch!

Learn more about the science behind the many benefits of hairy vetch in our in-depth article here.

Disadvantages to Hairy Vetch

I'm a big fan of hairy vetch, but there are some instances where it might not be the best cover crop to grow in your garden.

While hairy vetch provides numerous benefits, it's important to note that in some conditions, such as fields with existing nematode issues, it may exacerbate the problem rather than alleviate it.

Height

Advance Cover Crops notes that Hairy Vetch can grow quite tall. This can be a good thing for mulch cover. But it may make it difficult to terminate the crop with machinery. In most gardens under an acre, cutting back hairy vetch by hand or with a fence post crimper won’t cause much issue.

Persistence

Advance Cover Crops also shares that the seed of Hairy Vetch can persist in the soil for a few years. In fact, about 30% of Hairy Vetch seeds won’t germinate and will “hold” in the soil to germinate later on.

This could be seen as a benefit. The hairy vetch can be a companion plant to your crops. It can continue making mulch, or it might grow just in time for next year’s cover crop.

But if you’re a market gardener or need a “weed”-free garden for income, this might be problematic.

Please maintain your hairy vetch crop and do not allow it to spread or leave uncollected seed. It can become invasive in some areas.

Potential for Nematodes

Sustainable Agriculture Research and Education mentions that nematodes can sometimes increase in hairy vetch growth. This includes soybean cyst nematode and root-knot nematode. They recommend not planting this cover crop if your soil has these pests already.

It might be helpful to mix hairy vetch with cover crops that naturally reduce nematode populations. You might want to grow Tangerine French Marigold in that area if you notice root-knot nematode damage.

Alabama State University also notes that solarization of the area (subjecting it to high heat in the summer under a clear plastic tarp) also kills root-knot nematodes. They recommend a length of 4-6 weeks in the summer.

Use our checklist below to determine if hairy vetch is right for your garden's needs.

Conclusion:

If your goal is a sustainable and regenerative garden, then sowing a cover crop is a must in the autumn.

It's true that there area some instances where vetch would not be a good choice. For example, if you have nematode issues or already have high nitrogen levels in your soil.

Otherwise, hairy vetch is a great choice. If you're not sure what cover crop to plant, this one has so many benefits that you're bound to see a great result in your garden.

Want to learn more about cover crops? Check out my full guide to cover crop selection and benefits here.