Cover Crops For Gardens - Build Soil/Control Pests With Cover Crops

Cover Crops For Gardens - Clover And Vetch
This is a small patch of clover and vetch I've let stay through the summer.

The least expensive organic fertilizer in the world is - cover crops!

Cover crops for gardens are simply plants that are planted to cover your soil, especially during the off season.

And they can also be used during the growing season, interplanted with food crops or even in ornamental beds.

But they do much more than just cover the soil. Garden cover crops:

  • Reduce nutrient leaching, increase fertility and increase organic matter without the added expense of bringing in fertilizers and organic matter,
  • Control weeds and plant predators without every spraying a pesticide, as well as attracting beneficial insects and microbes without ever bringing in earthworms or ladybugs,
  • Prevent erosion, break up compacted soil, improve both drainage and water retention, all without rototillers or compost or buying mulch

Click for video transcription

Phil: New location, it got cold again. Hey guys, it’s Phil from smilinggardener.com. If you haven’t picked up my free online gardening course, you could do that right on the Home page of smilinggardener.com. Today we’re talking about cover crops for garden.

The least expensive organic fertilizer in the world is cover crops because just for a little bit of seed, which costs hardly anything you can do your whole garden and there are a lot of fertility benefits to cover cropping. So what a cover crop is, is when you plant some seed out into your garden, usually during the offseason when you don’t have any vegetables or anything else growing and you're doing for various reasons but usually to improve the health of the soil and of the garden in general.

Cover crops have a lot of benefits. One of the main ones I often think about is with fertility. If you were to leave your bed without any plants in it over the winter, it will lose a lot of nutrition especially if you get a lot of rain during fall, winter, spring, but if you have a cover crop in there, it’s going to retain those nutrients up into itself and then we’re going to return that cover crop to the soil in some way and so those nutrients are going to stay there. Likewise, it’s also increasing fertility by getting nutrients out of the soil.

The next one is weed and pet control, which I was talking about a couple of weeks ago. With weed control, just by having a crop there that densely covers your soil, it’s going to shade out and crowd out a lot of weeds from starting in the fall and again in the spring, but also many cover crops exude these compounds, we call them allelopathic compounds; basically these toxins that stop other seeds from germinating, so it controls weeds that way. Then with predators, there are many different ways, probably through some compounds that it exudes, they're going to control some predators but also by attracting beneficial insects into your garden and the last one is with organic matter.

A cover crop is photosynthesizing and becoming big and taking in carbon and we’re going to return that carbon to the soil, it’s going to be organic matter. So there’s a lot of fertility increases with cover cropping. So there are many benefits of cover crops. I just listed some of the main ones there and really, they just are about improving our soil and improving plant health, improving garden health.

What I want to do now is list the two different main kinds of cover crops which are legumes and grasses. So legumes are nitrogen-fixing plants, which means, they house these little bacteria on their roots and those bacteria can take nitrogen out of the air and turn it into nitrogen that can be taken up by plants. So they will use a lot of that nitrogen on their own. They may give a little bit up to the soil while they're growing, but mostly it’s when we turn those cover crops in or do something with them before they’ve gone to seed that that nitrogen gets put back into the soil.

One of my favorites is called vetch, which you can kind of see over here and which I’ll hold up to the camera. It’s like this and it grows kind of like almost like a vine. It really grows around and it will grow up any kind of trellis or any kind of other grass that might be around it and it’s a really good nitrogen producer. It’s one of the best in terms of making a lot of nitrogen. This is a red clover, an annual clover that is another good nitrogen producer. A white clover is often a perennial clover and it will be used – it could be used in a lawn or it could be used in an orchard, as a crop it’s going to come back every year and continue to produce nitrogen.

It’s starting to rain here a little bit. Now we’re on to grasses. What I really like about grasses is that they grow big and fast. They create a lot of organic matter for the soil, they control weeds really well because they grow really big and fast and also because they exude these allelopathic compounds into the soil and they also are really good at holding nitrogen and other nutrients in the soil, whereas clover is about creating the nitrogen, the grasses more are really good at holding that nitrogen and keeping it from leaching out.

Two of the main grasses are cereal rye and annual ryegrass. And they’re both know for having these toxins that are really good at controlling weeds and they're just very commonly used throughout much of North America. There are others, I really enjoy oats. I really love oats. They're great for climate like mine, it’s colder and wetter. There are many others.

So the cover crop usually goes into the soil late in the summer or early fall, gives a little bit of time to establish before winter and then it will really grow a lot in the spring before we deal with it in the spring. When it comes the time to decide what you're going to plant, there’s often going to be some local knowledge for your area. The farmers will know, but really what you need to do is just go to your – do a little research online or go to your local garden center and they're going to have crops that are appropriate hopefully. It doesn’t matter that much. That’s why I always say – just pick something and get some kind of crop always covering your soil. What I like to do is mix a legume and a grass and then I get the benefits of both.

So I might do a rye with a vetch, or a clover with an oats, and when spring time comes, those crops are going to start growing again and you want to figure out when you’re going to be planting into your soil which you should always wait for that because we get these late cold spells like we’re having right now and I'm glad I haven’t planted anything in here yet, but what I would do is figure – and we’re going to work backwards and if I'm going to be seeding directly into the soil, a few weeks before that, I want to take out the cover crop.

Now farmers will use herbicides for this if they're conventional farmers. Organic farmers will use some kind of a plough and what organic gardeners will use is this trusty old thing we used to get weeds to, which is a hoe and what you do is just hoe them down – hoe down, hoe them down just like you would a weed, maybe lightly incorporate them into the soil.

I'm not a fan of tilling too much, but if I just lightly incorporate them into the top of the soil, they're going to break down faster and they're going to retain more nutrition, especially nitrogen as less of it is going to be leached if I can lightly incorporate it. Some of it can be left as a mulch too and if you have too much or for some reason you don’t want it to be a mulch, you can move it over into a compost pit and that’s fine too. So it’s just like this. And even just by hoeing it kind of incorporates a fair amount; gets a little soil on top of it.

If you have any questions about cover crops for your garden, you can ask me down below and I’ll answer. If you haven’t signed up for my free online organic gardening course, you can do that down below. You can also join me on Facebook at facebook.com/smilinggardener. Phil out.

...And much more. Healthier soil, less work – what’s not to like?

The most common types of cover crops are legumes and grasses...

Legume Cover Crops

Legumes host nitrogen-fixing bacteria in their root nodules.

Fortunately, they contribute more nitrogen than they need for their own use, especially when they’re chopped down before going to seed.

Then their roots and leaves are allowed to decompose in the soil.

Some of the most popular overwintering legumes include vetch, various types of clover, fava beans, bird’s-food trefoil, cowpeas, and winter peas.

Which ones you use depends on your needs, but it’s most important just to pick one and roll with it.

Vetch has very high overall nitrogen production, while perennial white clover is a popular living mulch for use in orchards and ornamental gardens.

Red clover is often used as a dependable winter annual in eastern North America, while the tall and beautifully colored annual crimson clover is great for regenerating a fallow bed through summer in the west.

I’ve seen Austrian field peas, planted thickly in fall, completely displace persistent weeds in wildly overgrown beds. The peas sprout early in spring, shading the soil before the weeds have a chance to get going.

Grass Cover Crops

Grasses are great for creating lots of organic matter, controlling weeds, and reducing leaching of nitrogen and other nutrients.

They’re like chefs who can make a tasty and plentiful dish out of the leftover scraps.

They’re useful if your soil has a lot of nitrogen and other nutrients after harvest, because they’ll help prevent these nutrients from leaching away.

They also build humus effectively by growing fast and contributing cellulose and lignin.

Grasses are handy for their sheer exuberance – crowding out weeds with heaps of organic matter and by producing unfriendly root-zone “allelopathic” chemicals.

Because of those chemicals, it’s important to wait several weeks after removing the grass in spring before you seed vegetables.

High-carbon grasses take a lot longer than nitrogen-rich legumes to break down, though, so they may not be a great choice if your soil’s low in nitrogen, or if you need to plant in a hurry after turning in your garden cover crop.

The workhorses of winter cover crops for gardens are cereal rye and annual ryegrass. Oats can also be a good choice in areas with cold autumns and wet soil - they’re one of my favorites for my area.

Buckwheat, while not a true grass, is great for poor soils and for use in the shoulder season rather than over winter. And there are others, like barley, sorghum, and winter wheat.

Choosing Cover Crops For Gardens

Cover Crops For Gardens - Clover And Oats
I always try to mix a grass and legume - this is clover and oats (and garlic peaking through).

Among the many cover crops for gardens that are available, certain species and combinations are universally popular.

You’ll find that growers in your area may favor particular plants or grass-legume pairings, such as rye and vetch.

For home gardeners, the best way to select a cover crop is often to try a mix rather than choosing just one.

That way something should do well, whatever weather and soil conditions you have.

If you start with the basics, you can follow up on success by experimenting.

When to plant cover crops? I usually sow my cover crop seed in late summer/early fall so it can establish a little bit before winter. Then it will take off in spring.

Harvesting The Cover Crop

Cover crops for vegetable gardens are removed a few weeks before it’s time to seed, and usually at least a week before you transplant.

Giving the soil a few weeks to rest before you plant allows the cover crops to begin releasing nitrogen into the soil, and gives the allelopathic chemicals released by grass roots time to break down.

You’ll want to hoe down (I don’t mean the folk dance) most of your cover crop.

It’s best to incorporate it lightly into the top few inches of soil and leave some of it as a mulch, or second best would be to move it to the compost bin.

Farmers mostly use herbicides to kill the crop, but we’re trying to support the life in our gardens rather than kill it, so it’s worth relying on somewhat more labor-intensive tools like the hoe.

Any questions about cover crops for gardens? Or what do you use? Let me know below!

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