How To Prevent Weed Seeds From Germinating

Here’s how to keep weeds out of garden, mulch over weeds, use landscaping fabric, and 6 prevention mistakes to avoid for better garden weed control. Listed in this article are 5 effective ways to minimize weed growth in your garden / turf / landscape with Mirimichi Green. Learn how to prevent weeds and keep weeds from growing in your garden, lawn, and other landscaping areas with these gardening tips from HouseLogic.

How to Prevent Weeds From Growing

Tips on how to keep weeds out of the garden, add the right amount of mulch over weeds, and 6 mistakes to avoid to keep your garden weed-free.

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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. Let’s look at how to prevent weeds from growing.

(For those of you who already have weeds attacking your yard, read our article on How to Get Rid of Weeds.)

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.

Spread Landscape fabric and cut it to fit around plants. Photo by Saxon Holt

Fertilize Enough, but Not Too Much

Too little fertilizer can lead to sparse lawn that loses the competition with weeds. Too much helps nurture certain weeds, notably annual bluegrass, Bermuda grass and crabgrass. Strike a balance by following the application rates on the package. And use a fertilizer with a high percentage of controlled-release nitrogen, such as sulfur-coated urea, ureaform or IBDU. These provide a slow, steady nutrient supply.

The frequency and timing of your fertilizing efforts are also crucial to healthy lawns. Both vary depending on your lawn type and the length of your growing season. Most northern lawns need only one or two applications of fertilizer annually—once in fall and sometimes a second time in spring. Southern grasses might require three feedings—early to mid-spring just after the grass greens up, early summer and again in early fall.

Water Grass Infrequently and Deeply

Frequent, light watering causes shallow roots and helps annual bluegrass, crabgrass, chickweed, sedges and other weed seeds germinate. If you water too little, the lawn suffers while spotted spurge, Bermuda grass, quackgrass and other weeds adapted to drier soil thrive. Instead, provide your lawn with infrequent, deep soakings. Lawns need about 1 inch of water per week. Set an empty tuna can on the lawn to determine when you have applied 1 inch of water.

Can I Put Landscape Fabric Over Weeds?

Yes, you can. 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 3×50-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.

Photo by Saxon Holt

Smother Weeds 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.

How to Mulch Over Weeds
  1. After clearing a landscaped area of visible weeds, put down coarse-textured mulch up to 4 in. deep.
  2. Apply a fine-textured mulch that packs tightly, such as shredded leaves, to a depth no greater than 2 to 3 in.
  3. 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 the Irrigation and Green Industry Network in the “Where to Find It” section.

Mow Higher

Mowing too low weakens turf by reducing the ability of a grass leaf to produce enough nutrients. It also lets light hit the soil surface, which helps crabgrass and goosegrass seeds sprout and grow. Check with your local extension service for the recommended range of mowing heights for your grass type. Then mow at the highest level—usually between 2 and 4 inches.

Any weeds that grow through mulch are easy to pull because the soil remains loose. Photo by Saxon Holt

6 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.

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. Photo by Saxon Holt

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

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

5 Ways To Minimize Your Weed Growth

There are always weed seeds that lie dormant in the soil. The seeds are waiting for the sunshine to start to germinate or be awoken from a long slumber. To avoid awakening the weed seeds, don’t disturb the soil. Disturbing the soil includes tilling and cultivating. But that seems somewhat impossible when trying to plant new flowers, plants or grass. When planting flowers or plants, sow the seeds above the ground in a small mound of topsoil or compost.

2. Fight the weeds before they sprout

An effective way to prevent weeds is by using a pre-emergent herbicide that will stop weed seeds from ever germinating but won’t kill existing plants and grasses.

The tricky part is determining when to apply a pre-emergent because it must be applied before the weed seeds have time to germinate underground. The best way to know when to apply a pre-emergent is to make note of the date when you see the first weeds in the yard or garden. Then, mark your calendar 3 weeks before that date for next spring and apply the pre-emergent then.

You can also start from scratch by using a non-selective herbicide. This will kill whatever it sprays. It is also recommended to use organic options to prevent harmful synthetic build up in the soil. A great option is Mirimichi Green Weed Control. It is organic, OMRI listed and will show results in 24 hours.

3. Promote healthy plants & grass

If there is healthy grass, weeds will have less room to grow in the lawn. To promote a healthy lawn, reseed bald patches and fertilize if a soil suffers from nutrient deficiencies. By maintaining a healthy lawn, fewer weeds will arise. Nutri-Turf has the ideal balance of nutrients for all grass types and will keep the lawn lush.

4. Keep your plants close

Planting closely together will provide more shade to the soil below, which will prevent weed seeds from getting sunlight and allow less room for weeds to grow. You can usually reduce the recommended planting space on the packaging by about 25 percent. However, most spacing recommendations are based on the prediction that adjoining plants will not touch at their mature size, so follow the guidelines if you are planting plants that are prone to foliar diseases.

5. Create an organic barrier

Spreading an organic barrier around plants will submerge weed seeds and prevent light from starting germination all while keeping your plants cool. Organic barriers are best such as mulches. Mulches can host crickets and carabid beetles, which will feed on weed seeds. To create the organic barrier, spread mulch 2 to 4 inches deep around your plant bed.

Weed Control Tips to Prevent Them From Ever Sprouting

When it comes to weeds in your garden, an hour of prevention is better than a season of yanking.

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.

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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.

Topic

Lisa Kaplan Gordon

Lisa Kaplan Gordon is an award-winning, Pulitzer Prize-nominated writer who contributes to real estate and home improvement sites. In her spare time (yeah, right!), she gardens, manages three dogs, and plots to get her 21-year-old out of her basement.

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