Fast-growing annual cereal cover crop that produces abundant leafy growth and a dense fibrous root system. Oats help cover bare soil, take up excess nutrients, add organic matter, and compete with cool-season weeds. They make a particularly easy cover crop for vegetable beds because they are less persistent than winter rye.
When to sow: Sow in late summer through early fall for winter cover, ideally August through September in the Portland area. Spring sowing is also possible. Fall-planted oats may winter-kill during sufficiently cold weather, leaving a mulch over the soil.
How to terminate: If they survive winter, mow, cut, or chop down in spring before seed heads mature. For easiest incorporation or chop-and-drop, terminate while plants are still green and tender. Allow a couple of weeks for residue to begin decomposing before direct-seeding small vegetable seeds into the bed.
One pack covers 100 square feet. From Concentrates, Inc.
Avena sativa, Morton Oats seed
How to Use Your Cover Crop & Native Seed Packets
Each seed packet is measured to cover 1 sq ft, 5 sq ft, 25 sq ft or 100 sq ft, depending on the size you chose.
Sowing Instructions
When to sow: Fall is ideal in Portland. The soil is still warm for germination, and fall rains keep seedlings watered. Some seeds (like meadowfoam or clovers) can also be spring-sown.
How to sow:
Rake the soil lightly to create good seed-to-soil contact.
Scatter the contents of the packet evenly over the area (don’t worry about perfect spacing).
Gently press or rake seeds in so they make contact with the soil. Do not bury deeply — most native and cover crop seeds need light to germinate.
Water: Fall rains usually do the job, but water lightly if the weather turns dry.
What to Expect
Traditional Cover Crops (rye, peas, fava, daikon, crimson clover, buckwheat, mustard): Grow quickly, protect soil, and build fertility. In spring, chop them down or mow before they set seed. Some (like rye) can also be crimped into a mulch.
Living Mulches (red fescue, dwarf yarrow, creeping thyme, low clovers): These stay low and provide long-term weed suppression and ground cover. Shear lightly as needed, but they don’t require replanting every year.
Pollinator Wildflowers (Clarkia, poppy, gilia, flax, meadowfoam, coneflower, blanketflower): Not classic cover crops, but they add beauty and attract bees, butterflies, and beneficial insects. Many reseed naturally.
Spring & Summer Management
Chop-and-drop: Cut plants at the base and leave them as mulch (peas, fava, clovers).
Mow: Use on ryegrass or cereals to turn them into quick mulch.
Crimp: Flatten tall rye or grains at flowering to create a long-lasting weed barrier.
Shear perennials: Yarrow, thyme, and sedges can be trimmed back after bloom.
Self-seeders: Flowers like poppy, clarkia, and meadowfoam will often reseed themselves. Leave some seed heads if you want them back next year.
Quick Tips
Cover crops = soil builders.
Living mulches = weed suppressors.
Wildflowers = pollinator magnets.
Tulle or row cover can protect young seedlings from birds and slugs until established.