GHS Guide to Growing Fall Cover Crops in Your Home Garden

Cover crops growing in the garden

Farmers have long used cover crops to revitalize spent soil, but home gardeners can get just as much benefit from them. In times past, seed for cover crop was only available in big sacks, but that has changed, making the cultivation of cover crops something worth considering even if your garden is small.

In this newsletter we'll explain why growing cover crops is one of the best things you can do for your soil, and we'll help you choose the best cover crop for you. After that you just have to follow the directions that come with the seeds, and feel good about the harvest you're going to have after the cover crop has improved your soil's nutrient levels, structure, stability, drainage, and more.

Why Cover Crops

Soil literally wears out from having crops repeatedly grown in it because they leach the nutrients out until there is not much left. Those nutrients in veggies are a major reason why they're so good for you, but the soil that produced them also needs to be replenished. Fertilizer is not the ideal solution, especially long-term. For one thing, it gets washed away. But, more importantly, the growing process undermines soil structure and stability, and fertilizer can do nothing to fix that. By planting cover crops you will be able to restore both the nutrient content of your soil and also its structure and stability.

Other benefits of cover crops include improved soil drainage and aeration, decreased erosion, suppression of weeds, pest control, and reduced susceptibility to soil disease. Some cover crops break up compacted soil and attract beneficial insects. What's more, cover crops add valuable organic matter to your soil, similar to the enhancement you get from applying compost. You'll find that the veggies you plant in the future will grow bigger, taste better, and produce higher yields.

How Cover Crops Work

The way growing cover crops works is that after your summer harvest, instead of planting new veggies for the fall growing season, you instead sow a cover crop for the purpose of revitalizing the soil. You then mow it down at the correct time, or, in the case of radishes, you simply let them freeze over the winter, after which time they decompose under the ground. With all that rich, decomposed organic matter in your soil, it will be in terrific shape by the time you're ready for your next planting.

Varieties of Cover Crops

We sell nine different varieties of cover crops, five of which are a good choice to plant around this time of year: Sweet Clover, Hairy Vetch, Groundhog Radish, NitroRadish, and Annual Rye. The seeds we offer are available in quantities ranging from 5 lbs. up to 50 lbs., and we'd be happy to help you determine how many pounds of seed you'll need for your garden. We're always here, ready to answer these and other questions, so don't hesitate to drop us a line or call us at our toll free number: 1-888-907-4769.

Nutrient Adjustment Naturally

You probably know that doing a soil test is extremely easy and inexpensive these days, and is a vital step to making your garden grow optimally. It will also help you determine what cover crop to choose because if your soil is lacking in nitrogen or potassium, cover crops can be used to increase the amount of these key nutrients.

Through the use of cover crops, you can actually grow your own nitrogen. Sweet Clover, Hairy Vetch, Groundhog Radish, and NitroRadish will all increase the amount of nitrogen in your soil. These actually work far better than fertilizer to fix the nitrogen and make it fully available to whatever crops you'll be planting in the next growing season. By the way, both Groundhog Radish and NitroRadish grow well in drought conditions.

Annual Rye works differently: known as a nitrogen scavenger, it reduces nitrogen but increases potassium. It is therefore a great choice if you want to naturally shift the nutrient balance in your soil in the direction of more potassium (K) and less nitrogen (N). Rye also contains natural toxins that will suppress weeds and possibly even keep the pests away the next time you grow a crop. Farmers have long known that nematodes will not be found in a field where rye grass has been growing.

Be sure to at least do a simple NPK soil test so you'll know exactly where your soil stands in regard to those three essential nutrients: nitrogen, phosphorus, and potassium. To learn more about soil testing, read the GHS Guide to Soil and Soil Testing.

Breaking Up Compacted Soil and Hardpan

Another special use of cover crops is to break up compacted soil, hardpan, and the like. Our two radish varieties, Groundhog Radish or NitroRadish, both do a great job of this. Sweet Clover is also effective for this purpose. Each of these cover crops will improve soil drainage and aeration, whether your soil is compacted or not. That's because when they decompose, the roots leave large holes in the ground that extend down as far as two feet and deeper. For this reason, these kinds of radishes are sometimes referred to as bio-drills.

Tips and Advice for Growing Cover Crops

  • Of those cover crops named, rye is the easiest to grow; sweet clover is probably the most difficult.
  • In the northeastern United States, annual ryegrass should be considered first as a garden cover crop. As the plant scientists at Cornell University explain, It is a vigorous grower with an extensive root system that occupies the same root zone as the garden plants.
  • Think about when you would next like to use your garden. With most cover crops, you'll be ready to go the following spring, but if you plant Hairy Vetch it may not be ready to cut until the following June, and then you have to allow time for it to decompose. In other words, your ground will remain fallow for one year.
  • Master gardener Diana Roberts suggests that you trade off cover crops on one side of your garden for vegetable crops every other year, changing the cover crops when necessary and rotating vegetable crops from one side to the other. In this way, she explains, you won't have to forego a garden for one whole year, just use a portion of it. As soon as you harvest your vegetable crop, plant a cover crop. Through this technique she has eliminated the need for fertilizer.

Moving Forward With Cover Crops

We've prepared the following chart for you to bring together the information you'll need in order to make a decision as to what cover crop will be best for you. When you're ready to order, just click on the name of the crop(s) you want, and you will be taken directly to our website.

Thank you for your business and happy growing from all of us at Garden Harvest Supply!

Comparison of Four Fall Green Manure Cover Crops

Planting Time
Notable Features
Time Needed Before Mowing
Growing Tips

Annual Ryegrass Seed

End of August is ideal

Removes excess nitrogen; stabilizes soil and improves its structure, reduces erosion, controls nematodes and strongly suppresses weeds.

4–6 weeks, or wait until spring

Easiest cover crop to establish but needs to be kept moist. Will grow all right in compacted soil, and in other difficult conditions.

Groundhog Radish Seed

Late summer;early fall

Increases nitrogen; suppresses weeds,breaks up compacted soil.

No mowing necessary

Radishes are low maintenance, but roll ground after seeding to ensure good seed-to-soil contact.

Hairy Vetch Seed

Late summer;early fall

Increases nitrogen even more than peas; suppresses weeds, controls erosion, stabilizes soil, reduces surface hardness.

When it flowers, which may not be until the following June

Can be combined with rye for more biomass. Does not do well in compacted soil. Does do well inclay soil; slow to establish.

Yellow Blossom Sweet Clover Seed


Increases nitrogen;breaks up compacted soil; attracts beneficial insects; helps attract bees.

Leave it and then cut it down in the spring

Can grow in wet, poorly drained, alkaline, salty and low-fertility soils.Grows well in clay soils.

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    […] We also sell ground cover grass seed including annual ryegrass. Though typically used for field and pasture, annual ryegrass will keep your lawn green all winter if sown now. Some gardeners simply throw it onto their existing grass; it takes hold quickly and will leave your soil enriched when it comes time to reseed in the spring. For more about planting annual ryegrass, check out our GHS Guide to Growing Fall Cover Crops. […]

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