Organic Weed Control in the Summer Garden

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Peas mulched to keep down weeds

My man Roger is a wonderful weeder, though I must occasionally rein him in lest he take up the weeding tools and do more harm than good. Such a situation arose this week, just before he attacked the few weeds still lurking in the peas. "Don't weed the peas, they're already starting to bloom," I called from the other side of the garden. His hands flew into the air as if he'd been stung by a bee. A few weeks ago he accidentally weeded out the lettuce seedlings growing among the onions, which is enough humiliation for one season.

Later I explained the problem. Every crop has a "critical period" for weed competition, which is usually 6 to 8 weeks after sowing or transplanting. Weeds that are allowed to compete with young plants during this time will reduce yields, but weeds that are allowed to grow after the critical period has passed cause no harm provided they are not allowed to produce seed. Another factor in the organic weed control equation is the crop's sensitivity to root disturbance. A violent weeding session can set back peas and beans so much that they never recover, so almost-mature legumes are safest in the company of a few weeds. Cucumber family crops are easily damaged by late-season weeding, too. Even slight mangling of the vines can cause cucumbers, melons, squash or pumpkins to stop ripening properly.

Suppressing weeds around chard

Growing Green Canopies

Fortunately, vigorous vining cucurbits are capable of forming a dense canopy of green that shades out weeds. Sweet potatoes also provide their own organic weed control as the stems form a dense green ground cover. These talents can be used strategically in the summer garden when you locate canopy-forming crops near areas that would otherwise require constant monitoring for weeds. For example, when I harvest my garlic in a few weeks, I will replace it with winter squash (the seedlings are already growing in containers). The squash will form a weed-suppressing canopy in its bed and the adjoining row, which is occupied by sweet corn. Both crops will benefit in terms of reduced weed competition and the retention of soil moisture from the green canopy provided by the squash.

I like to use leafy greens to smother weeds, too, especially when growing onions, carrots, and other veggies that seem to go weedy overnight. Leaf lettuce sown between rows of onions or carrots shade out weeds and can be pulled before the preferred crop needs more space. From midsummer to fall, mustard greens will grow into a great green mulch that will choke out all but the nastiest weeds, and reduces soil-borne diseases if you chop it up and turn it under.

Growing Buckwheat as a nurse crop

Using Short Term Nurse Crops

Frequently there are short gaps in summer when one crop has finished, but it's not quite time to plant cool-season crops for fall. This is a great opportunity to use buckwheat or beans as "nurse crops" that will keep the soil busy and provide organic weed control until the space is needed. Then, you can pull out the nurse crop by the handful to make openings for seedlings of broccoli, bulb fennel or whatever.

Once the seedlings start growing, the remaining nurse crop plants can be pulled up and placed on the soil surface as mulch.

Working with little plots of nurse crops is fun, and much more enjoyable than watching your fall carrot bed go weedy before the first seed is sown.

Essential vegetable garden weeding tools

The Best Weeding Tools

I've written before on the importance of sharpening garden tools, and a sharp edge is absolutely crucial for taking down weeds that have gained a foothold in the garden. I also believe in precision weeding tools built for reaching into tight spaces, of which a current favorite is the long-handled Cobrahead weeder, which has eliminated a lot of bending and stooping. For hand-to-hand combat with well-rooted weeds, however, a razor-sharp Japanese Nejiri scraper simply has no competition. Once you've learned to use one, it can cut your weeding time in half.

To keep weeds from coming back, it's best to cover the soil's surface with a light-blocking mulch, which will also help keep the root zone cool and moist. Especially in summer, I like to double-mulch with newspapers (or brown packing paper) spread over the soil's surface, which is then covered with grass clippings, old leaves, aged sawdust or wood chips, or another biodegradable mulch. A paper base layer will enhance the organic weed control you get from any mulch, as it is doing now for me, covered with weathered sawdust, in our pretty and peaceful pea patch.

By Barbara Pleasant

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Show Comments


"Great article on Weed Control..thanks. Now, do you have a magical remedy for battling insects on kale or other greens. I've tried a solution of hot pepper, garlic, onions, but to no avail. I never see any insects, but I see the odd snail, I don't know what is eats my garden. "
Gaia on Friday 6 June 2014
"Take a breath, then figure out the problem. If you see snails during the day, there may be many more feeding at night that you don't see. The spray you describe will deter feeding by mammals, but not crustaceans or insects. Before you can take action, you need to identify the problem. Use your preferred search engine to find "name of plant" plus "holes in leaves" as a starting point. In general, leafy greens (except chard) have pest issues in late spring and summer, but not so much in the fall. Row covers are the ultimate solution. "
Barbara Pleasant on Friday 6 June 2014
"Try tomatoes juice and dish soap on your plants. Except tomatoes bugs nothing like tomatoes. The dish soap will help it stick. And for a snail trap try a pie plate with some beer in it. They really go for the yeast and then they drowned. Problem solved. "
Renee Brown on Saturday 7 June 2014
"My problem is not with weeds but more with Bermuda grass. Any suggestions on how to get rid of it from my garden?"
Janice Schwab on Wednesday 18 June 2014
"I would definitely call Bermuda grass a super weed -- it makes quackgrass look lazy! Its stolons are unstoppable, but you can manage them by creating a deeply mulched "moat" around your garden. The soft mulch makes it easier to catch invaders. Also, digging out all the Bermuda you can in the fall will give you a fresh start in spring. Good luck! "
Barbara Pleasant on Thursday 3 July 2014
"We live in Southern Italy and have just acquired a 1 acre plot spilt into several parts and on different levels and including an established orchard. All rotavated and "clean" as is traditional here. Over time we want to improve the soil organically and grow veg, fruit and various ornamentals and trees. Meanwhile as soon as we have any rain the weeds will leap up. What would you suggest as the best way to manage the land while we get going on creating compost and mulching material. Green manure perhaps? Landscape fabric maybe until we are ready for the newspaper method? We don't have loads of water for compost making but we are determined to find a way so any suggestions gratefully received."
Vicky on Saturday 18 June 2016
"By all means start using cover crops to build your soil and reduce weeds. Open soil is an invitation to weeds, so make a plan to keep the soil working. Buckwheat is a very fast warm-season cover crop you might want to try this time of year. "
Barbara Pleasant on Monday 20 June 2016
"what is the name of the weed in the very first picture on this page? I have a school project and Ive got to determine types of weeds and plants. Your picture looks very similar to my mystery plant but I cannot find any names for it. Would you by chance know what it is?"
Bryson Horner on Thursday 2 November 2017
"The plants in the top photo are peas, which have branches stuck in the row to hold them up . Any weeds there are in hiding."
Barbara Pleasant on Thursday 2 November 2017
"I bought a Nejiri hoe this spring. I have no idea how I managed without it. As you say, incomparable. At the same time, I also bought a hori-hori trowel. Brilliant for deep-rooted weeds. Neither in much use at the moment to avoid root disturbance. But what a difference diligent scraping with the Nejiri hoe earlier in the year has made now. I have a bit of bindweed, but nowhere near as much as before. And what bindweed I do have, I just snip off at the top and think "hah, I'll get you later". Very satisfying!"
Sue on Thursday 18 July 2019

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