Last Updated on September 17, 2026

Cover Crops for Raised Beds: What to Sow, How Much, and How to End It

The best cover crops for raised beds are oats if you want to plant early next spring, cereal rye or a rye and hairy vetch mix if the bed can wait until they flower in spring, crimson clover for flowers and nitrogen, and buckwheat to fill a summer gap. A 4×8 bed takes only about 1.3-1.9 ounces (36-54 grams) of rye or oat seed. None of them need digging in: oats die over winter and leave a mat you plant into, and the rest get cut at the soil line when they flower, roots left in the ground and tops left on the bed as mulch.

How much seed per bed, and when to sow it

The seed amounts below are the broadcast rates per 100 square feet from the planting chart in SARE’s Managing Cover Crops Profitably, scaled to a 4×8 bed (32 square feet, rate x 0.32) and a 4×4 bed (16 square feet, rate x 0.16). Sowing times count back from your average first fall frost. Look yours up with the Plan My Garden frost date finder.

Where the other columns come from: rye’s cold hardiness is from University of Vermont Extension, which also says rye sown around the first light frost still grows enough to give the soil some protection over winter. Oats dying in the first hard freeze and radish dying in most winters are from University of Maryland Extension. The -10°F line for crimson clover is from Wood Prairie’s crimson clover page, and Iowa State Extension adds that it may survive a mild winter or one with heavy snow cover; Iowa State is also the source for buckwheat as a 45-60 day cover. The oat, crimson clover and hairy vetch sowing windows and the vetch, pea and buckwheat notes are from SARE’s chapters on oats, crimson clover, hairy vetch, field peas and buckwheat. SARE counts oats and vetch back from the first killing frost. The radish window, sowing peas with oats, and oats surviving mild winters are from the New England Vegetable Management Guide.

For a mix, University of Maryland Extension says to sow about 60 percent of the single-crop amount of each. A rye and hairy vetch mix in a 4×8 bed is then about 0.8-1.2 oz of rye plus 0.4 oz of vetch. University of Vermont Extension says to sow a rye and legume mix several weeks before your first fall frost so the legume can establish before winter.

For a bigger area, multiply the per-100 column by 10: SARE’s rye and oat rate is 40-60 oz per 1,000 square feet, which is 2.5 to 3.75 pounds.

The guides do not agree on rates. For rye and oats, Iowa State Extension’s home garden chart lists 2-3 oz per 100 square feet, University of Maryland Extension 3-4 oz, and Penn State Extension 4 pounds per 1,000 square feet (6.4 oz per 100), so SARE’s 4-6 oz sits in the middle. For crimson clover SARE is the heaviest: Iowa State lists 0.4-0.6 oz and Maryland 1-2 oz per 100 square feet. Amounts this small are easiest to measure on a kitchen scale.

Which cover crop for which bed

A bed you want to plant early in spring: oats. University of Maryland Extension suggests oats for your first cover crop, and for beds going to early spring vegetables, because the first hard freeze kills them and leaves a brown mat. There is nothing to cut in spring; Illinois Extension says to plant straight into the mat. Field peas sown with the oats add a legume, and the New England Vegetable Management Guide says oats and field peas sown in fall make a reliably winter-killed mat. Radish dies over winter too; Maryland notes its taproot helps break up compacted or heavy clay soil.

A bed that empties late: cereal rye. It is the last cover crop you can sow, and Penn State Extension notes it still germinates at 35°F. The catch comes in spring. Rye keeps growing, and the New England guide notes it can delay spring planting. University of Vermont Extension says rye cut before it flowers simply grows back, so pick rye for a bed you will not need until it has flowered.

A bed you will plant or transplant in early summer: rye and hairy vetch. SARE calls hairy vetch ideal ahead of crops planted or transplanted in early summer. The rye protects the young vetch through winter and holds the vines off the ground so they are easier to cut in spring. It is the mix I plant in Prepare Your Garden for Winter: I sprinkle the seed and gently rake it into the soil.

Flowers and nitrogen: crimson clover. Clover, vetch and peas are legumes. University of Maryland Extension explains that their roots partner with bacteria that turn nitrogen from the air into a form plants can use, and they return a lot of it to the soil as they break down. SARE warns not to sow crimson clover too early, or it goes to seed in fall. Penn State Extension adds that legumes draw deer.

A summer gap: buckwheat. SARE says the seed germinates in three to five days, the leaves shade the soil within two weeks, and flowering can start within three weeks. It is often planted after an early vegetable crop comes out and followed by a fall vegetable.

How to sow a cover crop in a raised bed

1. Cut the spent crops at the soil line and leave the roots in the ground, as in Leave the Roots In. Perennial weeds come out, roots and all.
2. Rake the surface smooth. No digging.
3. Weigh the seed for your bed from the chart. University of Maryland Extension says mixing the seed with a little soil or compost makes it easier to spread evenly by hand.
4. For clover, vetch and peas, coat the seed with inoculant powder before sowing, as Maryland suggests. SARE’s planting chart lists the pea and vetch type for peas and vetch, and a crimson clover type for crimson clover.
5. Scatter the seed, gently rake it in, and press it down lightly so it touches soil. Cover peas well: SARE says pea seed left on the surface generally does not germinate well.
6. Water. Illinois Extension suggests every two to three days until the seedlings are up and 6 inches tall, then once a week.

How to end it without digging

Cut a cover crop once it flowers and before it sets seed. Cut too early and some grow back: University of Vermont Extension says to mow rye when the anthers are out and pollen falls from the heads when you shake them. Cut too late and it seeds itself into your bed. SARE notes that rye can turn into a weed if the seed heads start to mature, and that 10 to 20 percent of hairy vetch seed is hard seed that can sit in the soil for a season or more before sprouting.

The rye cutting stage is from University of Vermont Extension; the other cutting stages and the rye, oat and crimson clover waits are from SARE. The two-week waits are University of Maryland Extension’s general rule for letting a cut cover crop start breaking down. The rye wait is the longest because rye residue holds back small seeds for a while; SARE says that effect usually tapers off after about 30 days. SARE also notes buckwheat regrows if it is cut before about a quarter of it is in bloom.

Cut at the soil line. University of Maryland Extension lists a mower, a string trimmer or a spade for cutting a cover crop down; in a small bed, hand pruners work too. Leave the roots to rot in place, the same as spent vegetable crops. Leave the tops on the bed as mulch, or, as Maryland suggests when there is too much, add them to the compost pile. At planting time, rake the mulch aside to open a row or a spot for each transplant.

Or tarp it. Virginia Cooperative Extension suggests flattening a tall cover crop first with a lawn roller or a 2×4 or T-post tied to a rope, then covering it with a light-blocking tarp. In their observations a rye and crimson clover cover needed 5 weeks under a tarp in winter, while rye covered in spring died in 3 weeks; the authors think temperature and how mature the cover crop is set the time. Two cautions from the same guide matter on a raised bed: the sharp edges of wooden or metal beds rip silage tarps, so use woven polyethylene ground cover over a framed bed, and weigh the tarp down with bags rather than posts, boards or blocks that can poke holes in it.

Cover crop or compost?

Both beat bare soil. My rule, from Empty Raised Beds in Fall: a bed that empties early enough gets a cover crop where I have seed, and a bed that empties later gets two inches of compost and I walk away. To see what early enough means for your bed, count back from your own first fall frost with the chart above. Rye is the last one you can sow; if your frost is close and you have no rye seed, use compost.

Where to get the seed

Wood Prairie Family Farm sells organic seed for everything in the chart: Common Winter Rye, hairy vetch, a Rye-Vetch Mix, cover crop oats, Admiral peas, an Oat-Pea Mix, crimson clover, Tapmaster tillage radish and Common Buckwheat. Their oat, crimson clover and hairy vetch packets each plant 12 square feet, so a 4×8 bed takes three packets and a 4×4 bed two. A Rye-Vetch Mix packet plants 20 square feet, so a 4×8 bed takes two and a 4×4 bed one. Code PMG5 takes 5 percent off.

Quick questions

What is the best cover crop for a raised bed?

Oats if you want to plant early in spring, because they usually die over winter and leave a mat you plant into. Cereal rye, or rye with hairy vetch, if the bed can wait until the rye flowers in spring; cut it then.

How much cover crop seed do I need for a 4×8 raised bed?

About 1.3 to 1.9 ounces of cereal rye or oats, 0.6 to 1.0 ounce of crimson clover, or 0.6 ounce of hairy vetch. Those are SARE’s broadcast rates per 100 square feet scaled to 32 square feet.

Can I plant a cover crop without tilling?

Yes. Scatter the seed, rake it in lightly and water it. In spring, cut it at the soil line once it flowers, leave the roots in, and use the tops as mulch or compost, or cover the bed with a tarp for 3 to 5 weeks.

When should I plant a cover crop in a raised bed?

Count back from your first fall frost: crimson clover 6 to 8 weeks before, oats at least 40 to 60 days before, hairy vetch 30 to 45 days before. Cereal rye can go in last, up to about your first frost.

Should I cover crop or compost an empty bed in fall?

Either one beats bare soil. Sow a cover crop if there is still time before your first frost and you have seed; if not, lay two inches of compost on top and leave it.

Plan what goes in after it

When the cover crop comes down, the next question is what to plant and when. Plan My Garden is free to start: enter your zip code and it finds your frost dates, draw your beds, pick your crops, and it places each plant at square-foot spacing and builds a planting schedule (start indoors, transplant and direct sow dates) from those frost dates.

Related: Empty Raised Beds in Fall · Leave the Roots In · Composting for Beginners · Prepare Your Garden for Winter · Fall Gardening Checklist · Spring Garden Prep for Raised Beds · Charts and Tools