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Weed prevention: 9 ways to keep out invaders

by Timber Press on April 15, 2013

in Gardening

Image courtesy: Dennis Teague

Mulch can prevent weed growth, but gardeners beware, this pine straw came with an aggressive stowaway, Japanese climbing fern. Image courtesy: Dennis Teague

Since it generally is easier to prevent a problem than to solve one, you might want to consider ways to keep weeds from infiltrating your property rather than wait until an infestation occurs and then look for ways to eliminate it. Yes, weeds are resourceful and have seemingly unlimited ways of moving from place to place, but you can do something about them long before you learn the name of the enemy weed.

Here are nine ways to keep out invaders in the first place. Most of these are a matter of being vigilant. Weeds are opportunists, but can be slowed down or thwarted by a sharp eye and quick, appropriate action.

Don’t let looks fool you; this purple loosestrife may be pretty but it will easily crowd out native wetland plants. Image courtesy of John D. Byrd

1. PATROL YOUR YARD Walk around your yard regularly and keep your eyes open and your nose to the ground. Evict suspicious seedlings the moment you see them.

2. MIND THE BORDERS Abutting properties, whether a vacant lot, conservation land, or a nongardening neighbor, can bring unwanted, rampantly spreading plants to your yard. Look over the fence or past your property line, particularly at areas upwind from you. Talk to neighbors, where possible, and implore them to control any invasive plant(s). If they do not know what to do, review the options with them, make suggestions, or even offer to do the work for them (see the next chapter for many ideas). If that is not practical, create a barrier with a fence (sunk deeply into the ground) or a trench (filled with gravel, or bare) or a buffer zone (paving, paving stones, gravel, even mulch). The goal is to halt and thwart the invader’s advance onto your property.

3. COVER OPEN GROUND Few plants relish open ground as much as opportunistic weeds. Birds, squirrels, and other animals may deposit seeds deliberately or accidentally, seeds may blow in on a breeze or wander in via water (runoff), or dormant seeds and plant bits may awaken once the ground is cleared or stirred up. If you clear an area in your yard, do not just rake it over and leave it, not even for a day or two. Cover it with the mulch of your choice or a tarp until you are ready to plant it.

If it seems to good to be true it probably is. Kudzu was promoted as a “miracle vine” and used for shading, screening, as forage for livestock, and to combat soil erosion. It’s now known as the “vine that ate the South.”  Image courtesy of Joe Potato Photo

4. MULCH, MULCH, MULCH Nothing prevents weed growth better than a cloak of mulch. Mulch blocks light, air, and even moisture from getting through and nurturing seeds and seedlings that you do not want. Whether it is a vegetable patch or a flowerbed, mulch all open or bare spots around and between your desired plants. Over time, of course, the plants will grow and spread out and cover over the spaces with shading foliage, further preventing weeds. Keep an eye on things and replenish the mulch until they do, and maybe even beyond, because tenacious weeds might get a foothold and grow unnoticed until they burst upward or shove aside your garden plants.

5. AVOID TILLING THE SOIL Experienced gardening authors from Lee Reich (Weedless Gardening, 2001) to Edward Faulkner (Plowman’s Folly, 1943) remind us that digging up, traditional plowing,rototilling, and generally disrupting the soil can be counterproductive. Weeds may regenerate from chopped-up bits of plants, while dormant weed seeds are delivered to the light and oxygen they need to germinate and flourish. A main benefit of turning over the soil is to aerate it, but if it was not highly compacted in the first place, maybe you should rethink the practice. Your garden might be better off, and you will not work as hard, if you instead undertake soil improvement one new planting hole at a time. Coupled with diligent mulching between the new plants, this tack may surprise and delight you by dramatically reducing your weed population. Moreover, interlopers will not find openings.

6. INSPECT NEWCOMERS When you bring home a potted or balledand-burlapped plant from the nursery or garden center, look it over carefully before or immediately after planting it in its new home. Tiny pesky seedlings might be lurking. Check back often as the new plant establishes itself. Sometimes unwanted seeds that hitchhiked in via the soil mix do not germinate immediately but manifest themselves after a week or more.

Able to withstand pollution and dreadful soil, Tree-of-heaven can make your life hell. It emits chemicals to discourage other plants and its roots have been known to damage underground pipes and building foundations. Image courtesy of James H. Miller

Able to withstand pollution and dreadful soil, Tree-of-heaven can make your life hell. It emits chemicals to discourage other plants and its roots have been known to damage underground pipes and building foundations. Image courtesy of James H. Miller

7. EXAMINE AMENDMENTS Unwanted seeds and viable plant parts can sneak into your yard via a topsoil or loam delivery, farm and other mulches, cheap soil mixes, manure, and compost, as well as hay or straw. Designate a staging area for such deliveries and leave the new material there for a week or more before using. This will give you an opportunity to yank out any interlopers. Sifting the material through a screen or even your fingers as you add it to your garden may catch seedling invaders, but often not seeds. After you have used the new stuff, keep a wary eye on the spot where you put it and act immediately if you spot weeds growing there. You might have to pay more for quality, uncontaminated amendments. You should also spread the word to other gardeners when you find a bad source and especially when you find a good source.

8. KNOW WHAT YOU PLANT It is a good idea to add only plants whose identities you know to your yard and garden. Gift plants, free plants, sale plants, impulse purchases, incorrectly labeled plants, plants dug up by the roadside or taken from some wild setting—any of these might be trouble. Learn not only a newcomer’s name but also details about its appearance and habits.

9. BE A SAVVY SHOPPER Only buy plants you know or know of, and avoid those with a reputation for rampant, aggressive growth. If you think you see a “bad plant” for sale, speak to the seller. Make sure you have correctly guessed its name and bad nature, and if so, be bold and request that they not sell or grow it. Only patronize nurseries that sell healthy, correctly identified, garden-appropriate plants.


Text from How to Eradicate Invasive Plants by Teri Dunn Chace. Click on the image below to see page spreads from this book.


Every garden shed should have a copy of this book. The wisdom that it wields will hold the invaders at the gate. — Roger B. Swain, host of The Victory Garden

1 Marge June 27, 2013 at 6:41 am

Love the common sense approach she is advocating.

2 Brian Ridder June 27, 2013 at 11:44 am

Thanks for the comment, Marge. Teri’s book contains even more common sense advice (http://www.timberpress.com/books/how_eradicate_invasive_plants/chace/9781604693065). Do you have an invasive plant or weed problem where you are?

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