Cover Crops for Gardeners
Q. Mark writes: “I have been an avid listener of your gardening advice for several years and appreciate the wealth of knowledge you share. I am writing from Independence, Kansas, where the Verdigris and Elk Rivers meet to seek your expertise on a topic that has recently piqued my interest: “green manure”.
One of our local extension agents has discussed the use of cover crops, noting that many farmers are utilizing no-till drills to plant main crops of beans or corn without disturbing a cover crop of barley or oats. Those who don’t have a drill use a roller to flatten the cover crop.
Last fall, I found a deal on seeds for growing deer food and decided to plant the seeds, mostly oats and rye, in some of my garden patches. Now, I’m planning to roll them over in the spring to create a natural mulch. Following this, I’ll use a potato buster plow as a furrower to plant corn, beans, and squash.
I would greatly value your thoughts on this approach. Do you believe that rolling over the oats or rye to form a mulch and then using a furrower will provide a beneficial environment for my crops? Are there any potential pitfalls or additional considerations I should be aware of when adopting this method?”
A. Well, first I have to note that the last thing a gardener wants to do is get deer used to visiting their garden areas, which most—if not all—cover crops are going to encourage. Once this year’s fawns notice the nearby food source you’ve provided, it will be difficult to keep them away in the future.
Ok. By now, your oats have probably died off unless you had a VERY mild winter (which is possible in your Southern portion of Kansas). Nobody can predict whether rye will survive winter or not—it depends on the type of rye and your winter weather—but if it did survive, it’s going to become weedy and difficult to remove. Agricultural Bulletins for your area warn of this.
If you think about it, seeds of crops that are meant to feed deer over the winter are going to almost exclusively be planted by hunters and deer lovers to keep the populations well fed, not to improve the soil or be easily handled in a home garden.
To try and condense a nearly incondensable topic: There are two basic types of cover crops; plants that die over the winter and plants that do not ‘winter-kill’. This varies greatly by USDA growing zone as well as type of crop, so rather than buy something on a lark, it would be best to visit your local State Extension Office website and see what they recommend—and make sure the recommendations are for home gardeners. The vast majority of cover crops are used by farmers to grow grains that will be sold or used as forage, with the added advantage of their roots preventing erosion in what would otherwise be an empty field.
Some popular cover crops are also legumes, which means that—with the correct strain of bacteria either present or added to the soil—the plants will absorb Nitrogen from the atmosphere and store it in their tissues. Sadly, the belief that they spread this gaseous food underground to other plantings is not true. A leguminous cover crop has to be plowed back into the ground to ‘feed the soil’.
But plowing or rototilling such a crop uncovers masses of dormant weed seeds, allowing them to sprout and become nuisances that weren’t there before. The reverse is a major advantage of growing in raised beds; because you don’t step on and compress the soil, you never need to till, plow or double-dig it again. “Rolling” a crop to flatten it would also compress the soil, making it difficult for wanted plants to take up water and nutrients.
I have trouble wrapping my head around a cover crop that doesn’t winter-kill unless you’re resting a bed for a full season or growing a perennial forage crop. But I have long been a fan of cover crops that die over the winter.
Let’s use peas and oats as an example. Sow a 50/50 mix of edible peas and cereal oats in late summer if you garden in a region that gets a real winter. Inoculate the pea seeds to insure Nitrogen fixation. Harvest and eat the peas until frost. The oats will hold the soil in place and act as a living trellis for the peas while they’re growing. In early Spring, cut it all down to six inches to a foot high, making sure to harvest any seed heads off the oats over winter. (Note: Whole oats make a great high protein backyard chicken feed; and oat straw is an excellent mulch or ‘dry brown’ compost ingredient.)
Then use a bulb planter or similar device to punch planting holes in the now-dead cover crop and install your plants of summer. The dead cover will prevent weeds, and the roots of the peas will release Nitrogen as they slowly become one with the soil. The roots of the oats will have also loosened the soil for you.
Yes, this has been really simplistic, but it has to be. Because our listener lives so far South in Kansas that he’s almost in Oklahoma, the possibility of winter kill for many cover crops he could grow changes dramatically. So be sure to get really local advice—not just for your state or province, but for your portion of it.
One of our local extension agents has discussed the use of cover crops, noting that many farmers are utilizing no-till drills to plant main crops of beans or corn without disturbing a cover crop of barley or oats. Those who don’t have a drill use a roller to flatten the cover crop.
Last fall, I found a deal on seeds for growing deer food and decided to plant the seeds, mostly oats and rye, in some of my garden patches. Now, I’m planning to roll them over in the spring to create a natural mulch. Following this, I’ll use a potato buster plow as a furrower to plant corn, beans, and squash.
I would greatly value your thoughts on this approach. Do you believe that rolling over the oats or rye to form a mulch and then using a furrower will provide a beneficial environment for my crops? Are there any potential pitfalls or additional considerations I should be aware of when adopting this method?”
A. Well, first I have to note that the last thing a gardener wants to do is get deer used to visiting their garden areas, which most—if not all—cover crops are going to encourage. Once this year’s fawns notice the nearby food source you’ve provided, it will be difficult to keep them away in the future.
Ok. By now, your oats have probably died off unless you had a VERY mild winter (which is possible in your Southern portion of Kansas). Nobody can predict whether rye will survive winter or not—it depends on the type of rye and your winter weather—but if it did survive, it’s going to become weedy and difficult to remove. Agricultural Bulletins for your area warn of this.
If you think about it, seeds of crops that are meant to feed deer over the winter are going to almost exclusively be planted by hunters and deer lovers to keep the populations well fed, not to improve the soil or be easily handled in a home garden.
To try and condense a nearly incondensable topic: There are two basic types of cover crops; plants that die over the winter and plants that do not ‘winter-kill’. This varies greatly by USDA growing zone as well as type of crop, so rather than buy something on a lark, it would be best to visit your local State Extension Office website and see what they recommend—and make sure the recommendations are for home gardeners. The vast majority of cover crops are used by farmers to grow grains that will be sold or used as forage, with the added advantage of their roots preventing erosion in what would otherwise be an empty field.
Some popular cover crops are also legumes, which means that—with the correct strain of bacteria either present or added to the soil—the plants will absorb Nitrogen from the atmosphere and store it in their tissues. Sadly, the belief that they spread this gaseous food underground to other plantings is not true. A leguminous cover crop has to be plowed back into the ground to ‘feed the soil’.
But plowing or rototilling such a crop uncovers masses of dormant weed seeds, allowing them to sprout and become nuisances that weren’t there before. The reverse is a major advantage of growing in raised beds; because you don’t step on and compress the soil, you never need to till, plow or double-dig it again. “Rolling” a crop to flatten it would also compress the soil, making it difficult for wanted plants to take up water and nutrients.
I have trouble wrapping my head around a cover crop that doesn’t winter-kill unless you’re resting a bed for a full season or growing a perennial forage crop. But I have long been a fan of cover crops that die over the winter.
Let’s use peas and oats as an example. Sow a 50/50 mix of edible peas and cereal oats in late summer if you garden in a region that gets a real winter. Inoculate the pea seeds to insure Nitrogen fixation. Harvest and eat the peas until frost. The oats will hold the soil in place and act as a living trellis for the peas while they’re growing. In early Spring, cut it all down to six inches to a foot high, making sure to harvest any seed heads off the oats over winter. (Note: Whole oats make a great high protein backyard chicken feed; and oat straw is an excellent mulch or ‘dry brown’ compost ingredient.)
Then use a bulb planter or similar device to punch planting holes in the now-dead cover crop and install your plants of summer. The dead cover will prevent weeds, and the roots of the peas will release Nitrogen as they slowly become one with the soil. The roots of the oats will have also loosened the soil for you.
Yes, this has been really simplistic, but it has to be. Because our listener lives so far South in Kansas that he’s almost in Oklahoma, the possibility of winter kill for many cover crops he could grow changes dramatically. So be sure to get really local advice—not just for your state or province, but for your portion of it.
