From blocking pure light to shading the soil, cover crops prevent weeds in many ways Learn how to prevent weeds and keep weeds from growing in your garden, lawn, and other landscaping areas with these gardening tips from HouseLogic. Cover crops differ from ‘regular’ crops in that they are grown solely so the soil is covered, rather than for harvestable things. Cover crops are used by lots of folks – grain farmers, vegetable farmers, flower farmers, and they offer lots of soil benefits, as described in this blog. But they can also help control…
How can you prevent weed seeds from germinating in your garden?
Newswise — March 22, 2021 – Have you ever considered using a cover crop in your home garden? Farmers use them often. Cover crops have a lot of benefits, including weed control! This Sustainable, Secure Food blog explores the life of the weed seed and how cover crops can prevent these unwanted seeds from germinating in your garden. The blog post is part of the 2021 Seed Week celebration, organized by the Crop Science Society of America.
According to blogger Gina Nichols, cover crops can prevent weeds by:
- Providing protection for seed-eaters. It’s harder for a hawk to see a mouse running along the ground if there’s a cover crop. The mice protected by the cover crop will eat a lot more seeds.
- Preventing weed seeds from germinating. Weed seeds will only germinate when they sense pure light, which is blocked by the cover crop.
- Competing with weeds for resources. Cover crops hog a lot of the things a seed needs, including light, water, and nutrients.
To learn more about the benefits of cover crops and how to integrate them into your garden, read the entire blog: https://sustainable-secure-food-blog.com/2021/03/22/how-can-you-prevent-weed-seeds-from-germinating-in-your-garden/
About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified professionals in the areas of growing our world’s food supply while protecting our environment. They work at universities, government research facilities, and private businesses across the United States and the world.
Credit: Gina Nichols
Caption: A happy garden area goes into the winter covered by a winter rye cover crop at Mustard Seed Community Farm in Ames, Iowa.
Credit: Gina Nichols
Caption: A winter rye cover crop is preventing small weed seedlings from growing.
Credit: Gina Nichols
Caption: Seed-eaters such as mice can hang out and eat weed seeds under cover crops, safe from predators.
Weed Control Tips to Prevent Them From Ever Sprouting
Unlike seeds and plants you buy from catalogs and nurseries, indigenous common weeds are naturally suited to the sun, soil, and water conditions of your garden. That’s why weed control is so hard.
But if you prevent weed seeds from germinating, your garden will be weed-free. Here are some surefire ways to keep weeds from growing in the first place.
Don’t Disturb the Soil
Weed seeds “sleep” in your soil all the time, just waiting for sunshine to enable them to germinate. Left underground, many weed seeds remain dormant for years. So the less you disturb the soil, the more likely weed seeds will remain asleep.
Avoid high-powered tillers, and go easy on the hand cultivating. Sow your flower and vegetable seeds above the ground in mounds of compost, shredded leaves, or even in bags of topsoil. Better yet, plant seedlings and starts.
Smother Weed Seeds
Another way to keep seeds asleep is to cover your soil with sun-blocking organic or synthetic mulches.
Organic mulches — hardwood mulch, newspaper, cardboard, straw — degrade in a few months and improve soil structure and add nutrients. Synthetic mulches — landscaping paper, plastic — can last several seasons, but won’t help rebuild soil when they eventually degrade.
Heed these mulching tips:
- Wet the ground before you lay down layers of paper, which will prevent the paper from blowing away while you work.
- Scout yard sales for old carpet and wallpaper, efficient sun blocks that prevent weeds.
- Spread mulch 2 to 4 inches deep to suppress weeds and retain moisture.
- Always pick straw, not hay, to prevent weeds. Hay usually contains hayseeds, which will sprout where you’re trying to keep weeds out.
Learn more with our handy mulch guide.
Wage a Chemical Attack for Weed Control
Pre-emergent herbicides prevent weed seeds from germinating, but don’t kill existing plants and grasses.
The exact timing for applying a pre-emergent herbicide is hard to pinpoint because you must spread the herbicide before seeds germinate, which happens underground at different times.
Conventional gardening wisdom says spread pre-emergent herbicides when the daffodils pop or the forsythia wilts. But advance planning is the best way to determine when to spread. Log the date when you see the first weeds in your garden, then subtract three weeks to arrive at the date you should spread the pre-emergent herbicide next spring.
Grow Plants Close Together
The closer together you plant your flowers and vegetables, the less space weed seeds will have to grow.
If you double-dig — loosen (don’t pulverize) soil at least 2 feet down — you can plant cheek-by-jowl, because plant roots can grow down, not out, to find water and nourishment. If you plant intensively in a diamond-shaped pattern — rather than rows — you’ll avoid barren spots where weeds will grow.
How can you prevent weed seeds from germinating in your garden?
Cover crops differ from ‘regular’ crops in that they are grown solely so the soil is covered, rather than for harvestable things. Cover crops are used by lots of folks – grain farmers, vegetable farmers, flower farmers, and they offer lots of soil benefits, as described in this blog. But they can also help control weeds! Let’s explore how.
First, let’s think about the life of a weed seed. Better yet, let’s pretend we are a weed seed trying to grow in your garden. We’ll start sitting in or on the soil. One of the biggest threats to a seed is something most people don’t normally think about: getting eaten. Mice, crickets, beetles, ants, birds (including chickens) – these things all love to eat the seeds sitting in the soil. Often the seed-eaters are themselves constantly in danger of getting eaten. A cover crop provides protection for seed-eaters. It’s harder for a hawk to see a juicy mouse running along the ground if there’s a cover crop. The mice protected by the cover crop will eat a lot more seeds.
Seed-eaters such as mice can hang out and eat weed seeds under cover crops, safe from predators. Credit: Gina Nichols
Pretend you, the weed seed, didn’t get eaten. It’s time to think about germinating. But you, the weed seed, can only germinate if you get the right ‘cues’. Weed seeds are incredibly smart. A lot of weed seeds will only germinate when they sense ‘pure light’. Light changes as it passes through green leaves. Weeds don’t want competition, so they will wait until there are no other living plants around before they germinate. So, what if you planted a cover crop? The cover crop, alive or dead, is blocking that pure light from hitting the soil, where you and your weed seed friends live. You might never get the cue to germinate.
Another cue seeds look for is large swings in temperature. If the soil gets really warm during the day, then cools back down at night, this is a cue there isn’t anything trying to compete with it. Under a cover crop, the soil is shaded during the warm parts of the day, so the temperature swings are much less drastic. You might sit there waiting for a cue for a long time. But the longer you sit there, the higher the chance you’ll get eaten by one of the seed-eaters.
Let’s say you managed to get all the cues you needed to germinate. Congratulations, you are a weed seedling! But your fight is just beginning. The cover crop is hogging a lot of the things you need – light, water, nutrients – it’s stealing resources. And the cover crop is bigger than you, you’ll most likely just get the ‘leftovers’. The cover crop is making your life hard, so you are not going to flourish. And again, there is the threat of being eaten. Mammals love to eat tender little seedlings, and again they love to hang out under the protection of the cover crop, so your chances of survival aren’t great.
As you can see, using a cover crop can make the life of a garden weed much more difficult. In fact, many community gardens plant cover crops in plots that don’t have an owner, just to prevent weeds from taking over. To recap, cover crops can prevent weeds by:
- Providing protection for seed-eaters
- Preventing weed seeds from germinating
- Competing with weeds for resources
Are you sold? Here are three ways you can start integrating cover crops into your garden.
A simple way to get started is to plant a winter rye cover crop in the fall (October/November) as you put the garden to bed. Many gardening seed companies offer winter rye seeds. It’s a hardy plant that survives most winters if it gets to be one soda can tall before winter truly sets in. It also puts a satisfying ‘green’ in the garden during months that can feel dreary.
You want fall-planted cover crops to be about one soda can tall before Thanksgiving. Credit: Gina Nichols
If you are reading this in December, you might think you’ve missed your cover-cropping chance. You’re wrong! You can plant an early-season cover crop such as oats and hairy vetch as early as March. Good garden areas for these include places destined for crops you’ll transplant in the summer (pumpkins, eggplants, tomatoes), or pathways you want to keep from getting weedy.
If it gets to summer and you find you have some empty space, buckwheat is an excellent summer cover crop. It grows quickly, bees love the flowers, and is easy to kill by mowing or pulling.
For all cover crops, you need to make sure the cover crop is dead before you plant your harvesting crop. Some cover crops will die if you mow them, but others need to be pulled (you can place the pulled plants back on the ground to keep it covered), crimped (imagine stomping on the plants to break their stems), or tilled. If the cover crop is still alive, it will compete with the main crop for nutrients and light, which you don’t want.
A happy garden area goes into the winter covered by a winter rye cover crop at Mustard Seed Community Farm in Ames Iowa. Credit: Gina Nichols
Some other common cover crops are clovers, peas, tillage radish, mustards, barley, wheat, and Sudan grass. Many gardening companies also offer seed mixes. Once you start using cover crops you might find they are just as exciting as the food-producing plants in your garden. As a rule of thumb if you see bare soil you might have an opportunity to use a cover crop, the quiet weed fighter. Happy cover cropping!
Answered by Gina Nichols, Iowa State University
This blog is part of Crop Science Society of America’s Seed Week celebration. Why celebrate seeds? Anyone who plants a seed is investing in hope. That’s one of the attractions of seeds. For the gardener, it could be hope for a beautiful flower, or perhaps a delicious zucchini squash. For our farmers, seeds are the hope of this year’s yields of produce, cash crops or forage. No matter the size or shape of the seed, they all can bring forth new life. At Crop Science Society of America, we hold seeds in very high regard. Please visit our Seed Week webpage for news stories, blogs and more information about seed research and facts.
Please visit our Seed Week webpage for more information.
Read the other blogs in our seed series!
About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.