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Say Good-bye to Weeds

Think it's an overstatement to call it the war against weeds? Here's what you're up against.

controlling weeds
Photo by Bill Lorenz
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Think it's an overstatement to call it the war against weeds? Here's what you're up against. A single redroot pigweed is able to produce up to 30,000 seeds in a season. And those seeds can remain alive in the soil for 70 years waiting to sprout and overrun your perennial border at any time. Controlling weeds is a fight you can't win entirely because they always grow back. But you can keep weeds under control by depriving new ones of the conditions they need to take root in the first place and then removing those that sprout.
Think it's an overstatement to call it the war against weeds? Here's what you're up against. A single redroot pigweed is able to produce up to 30,000 seeds in a season. And those seeds can remain alive in the soil for 70 years waiting to sprout and overrun your perennial border at any time. Controlling weeds is a fight you can't win entirely because they always grow back. But you can keep weeds under control by depriving new ones of the conditions they need to take root in the first place and then removing those that sprout.
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install landscape fabric
Photo by Saxon Holt
Spread Landscape fabric and cut it to fit around plants.
STEP 1: Weed Prevention
As with most types of prevention, discouraging weed seeds from sprouting requires some extra time now so you can save a lot of time later. When weeds have already taken hold in a section of your yard, remove them before planting. Pull them by hand if possible, or use an herbicide such as glyphosate (Roundup), and apply it with caution. This nonselective chemical will kill almost all plants. As always, carefully read directions before using. Install landscape fabric.

Synthetic landscape fabrics provide a physical barrier to weeds yet allow air, water and nutrients through to plant roots. Spread the fabric over bare soil around trees and shrubs; overlap several inches of fabric at the seams. Anchor the material with U-shaped metal pins, then conceal it with 1 to 2 in. of mulch, such as stone or bark chips. You can also use landscape fabrics to control weeds under decks and in pathways (spread over the excavated soil base before you add gravel or sand). A 3x50-ft. roll of landscape fabric, such as the Typar shown below, costs about $10. The fabric is also available in 36-in. die-cut circles (about $3 each) for installing at the base of trees.
Smother with mulch.
Left unattended, weeds will quickly fill in unplanted areas and any open ground around plants. Mulch spread over the soil surface blocks the sunlight most annual weeds need to take hold. Weeds that do sprout are easy to pull because soil beneath mulch remains loose and moist. Coarse chipped or shredded bark is a good choice for large areas between trees and shrubs because it decomposes slowly and doesn't easily blow away. For paths, a thick layer of sawdust provides good weed suppression because it depletes nitrogen in the soil.

After clearing a landscaped area of visible weeds, put down coarse-textured mulch up to 4 in. deep. Apply a fine-textured mulch that packs tightly, such as shredded leaves, to a depth no greater than 2 to 3 in. Keep the mulch a few inches away from the trunks and stems of plants to prevent disease problems. Apply preemergence herbicides.
Preemergence herbicides, such as those containing oryzalin or trifluralin (look on the label for these chemicals), or nontoxic corn gluten meal, kill weeds just as they germinate and will not eradicate established weeds. For a preemergence herbicide to be effective, you must apply it to soil cleared of visible weeds; also, you have to water most of these herbicides into the soil.

Check the label to determine if it is safe for use around the kinds of landscape plants you have and effective against the weeds normally present. Deprive weeds of water.
Weeds can't survive without moisture. In areas with little or no summer rain, drip irrigation or soaker hoses help prevent weed seeds from sprouting by depriving them of water. These systems deliver water to the root zone of plants at the soil level. The soil surface and area surrounding the plants stays relatively dry. In contrast, overhead sprinkler systems spray water over the entire soil surface and supply both garden plants and weeds with water.
You can get in-depth information on drip irrigation from Michigan State University and the Irrigation and Green Industry Network in the "Where to Find It" section .
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Landscape fabric
Photo by Saxon Holt
Overlap the fabric pieces to prevent weeds from growing, and secure fabric with landscape staples.
STEP 2: Pull Them When You See Them
Preventive methods minimize weeds but do not provide total control. You have to eliminate weeds as they appear and keep at it. Weeds decline significantly over a couple of years if you persistently catch them before they set seed. The following products will make the job easier. Pry weeds from paving.
The Telescoping Crack Weeder ($9.95) from Lee Valley Tools removes grass and other weeds from crevices in patios and walkways. The L-shaped stainless-steel blade fits between bricks and other pavers to reach and scrape pesky plants. The aluminum handle adjusts from 28 to 45 in., which means you can weed kneeling or standing. Off with their heads.
The scuffle hoe (also called an oscillating or action hoe) gets its names from the double-edged hinged blade that rocks back and forth with a push-pull motion. As it rocks, it slices weeds off at the crown. Repeated beheading depletes the weed roots of stored food and the plant dies. Shallow cultivation also avoids bringing more weed seeds to the surface where they can sprout.

The hoe, like this one from True Temper Hardware ($15), works best in somewhat compact soil, on paths or in garden beds. Flame weeds.
Gas-powered flamers kill weeds by heating them to the point that their cell walls burst. A single pass with the flamer, such as the Primus Gardener Weed Destroyer shown ($46.95), kills young annual weeds. They won't look charred but will die within a few hours. Tough perennial weeds with deep roots usually regrow and require repeated treatments. Never use a flamer in an areas that's dry and fire-prone, or in planting beds covered with flammable mulch. Spot weed with herbicides.
You can kill individual weeds in established plant-ings, if you use the right product in the right way. Products containing fusilade, for example, selectively kill actively growing grassy weeds and won't harm specific ornamental plants, which are listed on the product label. In contrast, you have to use all non-selective herbicides with extreme caution to prevent harm to desirable plants. Among them, contact herbicides, such as herbicidal soaps, kill only the plant parts on which they are sprayed. They are most effective on young or annual weeds. Systemic herbicides, such as those containing glyphosate or glufosinate-ammonium, kill annuals and perennials, roots and all.

If you have questions, consult your local nursery or extension service office. Also, check out the Iowa State University site at www.weeds.iastate.edu, and the Weed Science Society of America at www.wssa.net. While there is no miracle cure for weeds, you will reduce the time you spend fighting these pests by choosing a control strategy that works and sticking with it.
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smother with mulch
Photo by Saxon Holt
Any weeds that grow through mulch are easy to pull because the soil remains loose.
Six Weeding Mistakes In the process of trying to eliminate weeds, people often make mistakes that lead to more weeds. Here are the most common: 1. Leaving weeds that are in flower on the ground. Even after they are pulled, weeds like chickweed and purslane can continue to develop seeds. 2. Piling too much mulch over landscape fabric. As the mulch breaks down, it provides a perfect medium for weed growth from wind-borne seeds. You can actually have weeds rooted to the fabric. Limit mulch depth to 1 or 2 in. over landscape fabric. 3. Applying mulch containing weed seeds. Sometimes mulches such as straw and wood chips contain weed seeds. To avoid this problem, buy from a reputable nursery that offers mulch free of weed seeds. 4. Tossing weeds with seeds into the compost pile. A good compost pile can get hot enough (160°F) to kill weed seeds. But there are often cool spots where the seeds can survive. Those that do will be spread in your garden with the compost. 5. Breaking apart the roots of perennial weeds as you try and dig them out. Each piece can grow into a new plant. 6. Planting weeds along with your new shrubs and trees. Just a few nutsedge or Bermuda grass plants growing in a nursery container can spread and multiply in your garden. Make sure to remove them before planting.
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Herbicide
Photo by Saxon Holt
This Preemergence herbicide, made from corn gluten, is nontoxic. You can safely use it near all of your vegetables as well as around ornamental plants.
Where to Find It: Lee Valley Tools Ltd.
Box 1780
Ogdensburg, NY 13669-6780
800/871-8158
Telescoping Crack Weeder True Temper Hardware
Box 8859 Camp Hill, PA 17011
800/393-1846
Scuffle hoe Drip irrigation information and supplies:
Irrigation & Green Industry Network
916C N. Formosa Ave.
Los Angeles, CA 90046
www.igin.com
323/878-0318 Michigan State fact sheet,
www.msue.msu.edu/msue/imp/mod03/03900058.html. Raindrip Inc.
2250 Agate Ct.
Simi Valley, CA 93065
www.raindrip.com
877/237-3747
Request the free "Drip Watering Made Easy" guide. Denman & Co.
401 W. Chapman Ave.
Orange, CA 92866
714/639-8106
Ball weeder Primus
Box 186
Cherry Valley, IL 61016
815/332-5504
Weed flamer Reemay, Inc.
70 Old Hickory Blvd.
Box 511
Old Hickory
TN 37138-3651
www.reemay.com
800/321-6271
Landscape fabric
 
 

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