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.)
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
- 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 the Irrigation and Green Industry Network in the “Where to Find It” section.
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:
- Leaving weeds that are in flower on the ground. Even after they are pulled, weeds like chickweed and purslane can continue to develop seeds.
- 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.
- 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.
- 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.
- Breaking apart the roots of perennial weeds as you try and dig them out. Each piece can grow into a new plant.
- 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.
Ogdensburg, NY 13669-6780
Telescoping Crack Weeder
True Temper Hardware
Camp Hill, PA 17011
Drip irrigation information and supplies:
Irrigation & Green Industry Network
916C N. Formosa Ave.
Los Angeles, CA 90046
2250 Agate Ct.
Simi Valley, CA 93065
Request the free “Drip Watering Made Easy” guide.
Denman & Co.
401 W. Chapman Ave.
Orange, CA 92866
Cherry Valley, IL 61016
Do Lawn Seed Blankets Work? (Quick Read)
As someone into lawn care who enjoys mowing the grass, I don’t like it when patches of grass dry up and become discolored – but that’s where a lawn seed blanket can help.
Lawn seed blankets, also known as grass seed germination blankets and erosion control mats, work well at preventing grass growing in clumps to give a uniform lawn. They can also help with soil erosion and are an alternative to scattering grass seeds directly onto the earth.
Let’s dive down into the subject of lawn seed blankets in more detail, and discover how and why to use them in your yard…
Table of Contents
Do Grass Seed Germination Blankets Actually Work?
Grass seed germination blankets (also known as lawn seed blankets and erosion control mats) are an alternative to scattering grass seeds directly onto the earth.
They can work really well, as they are simple to use, prevent grass from growing in clumps, and should give you a nice, uniform lawn. They are also recommended if you experience soil erosion in your yard.
If you scatter grass seeds, it’s pretty much impossible to make sure that you don’t end up with clumps and bald patches. If a too-dense patch of seeds starts to germinate, they will start to strangle each other. A pre-seeded lawn seed blanket gives you a more uniform approach, with the seeds nicely spread out.
The blanket holds the seeds safely in place, so they won’t get washed away by rain, eaten by the birds, or dug up by the dog. It will also prevent the soil from being disturbed or washed away, hence the alternative name of “soil erosion mat/blanket”. As well as preventing the rain from disturbing the seeds, the blanket also locks in the right amount of moisture for the germinating grass.
Another (big) advantage is that it makes it tricky for weeds to grow up around the new grass. Weeds love the tilled soil and regular watering that grass seeds need, and a germination blanket helps prevent them from taking advantage of these conditions.
As you can see, there are a lot of advantages to using a lawn seed blanket. The main disadvantage is increased cost (a simple pack of seeds costs very little) and the fact that you have less choice of seed types.
Not all lawn blankets come pre-seeded. You can also buy “bare” blankets that simply cover the planted seeds and help to create the right environment for successful germination and growth. This can be a good solution if you just want to patch up a few places, or if there’s a specific type of grass you want to grow.
Of course, if you go for an unseeded lawn blanket, you’ll still need to make sure that you sow the seeds carefully and evenly by hand, into soil that’s been enriched with a suitable fertilizer.
Can a Seed Blanket Be Used On An Existing Lawn? (Or Just For New Grass?)
Yes, seed blankets can be used on existing lawns. If you have some bald or sparse patches on your lawn that you want to cover, a grass seed blanket can help make sure that your new seeds grow successfully.
You’ll need to start by giving the whole lawn a good mow. Then, you can either cut up a ready-seeded germination blanket, or sow seeds into the ground and cover them with pieces of non-seeded blanket. The latter option can be better if you have a more specialist type of grass and don’t want to mix two varieties. Hold the blanket pieces in place with biodegradable stakes.
How Do I Use a Seed Germination Blanket On My Lawn?
It’s super-easy to use a seed germination blanket on your lawn, which is one of the reasons why more gardeners have started using them.
There are two approaches, depending on whether you choose a blanket that’s already impregnated with seeds, or choose to seed then cover your lawn area.
- Measure your lawn area to work out how much seed blanket you will need
- Seed mats are usually sold on rolls. Unroll the mat across the soil, taking care not to miss any patches or create unsightly joins
- Stake the blanket in place with biodegradable stakes (more about where to buy everything in a moment)
- Water it well
- Different manufacturers give different lengths of time between putting down the mat and the grass sprouting up. Grass Daddy’s video shows you how to use a germination blanket on a sloping and tricky patch of ground.
- Mow and rake the existing grass
- Prepare the bald or sparse patches of lawn ready for planting seeds, with tilling and adding fertilizer
- Measure the bald or sparse patches, and cut pieces of blanket to fit them
- Using seeds that are the same grass species as your existing lawn, sow them in the bare patches
- Cover these with the ready-cut pieces of blanket
- Stake them into place with biodegradable stakes
- Water it well
You don’t have to use a lawn blanket: if you have access to hay, this can make an alternative cover while the seeds grow. However, it’s not as fool-proof as a proper blanket, and doesn’t have the same protection against erosion.
When Do I Remove The Lawn Seed Blanket?
The great news is that most lawn blankets are biodegradable and you won’t have to move them at all. Most types of both pre-seeded and unseeded come with a green finish, so they don’t make your yard look too weird while the young grass grows.
Pulling them up can be a risk, as the seedlings will come up with the blanket. So, the best solution is to be patient, and let the blanket gently biodegrade into the lawn after all the grass has grown through it.
Where Can I Buy a Lawn Seed Blanket?
Lawn seed blankets are easy to buy, and you can pick them up at places like Lowe’s or your local garden center. Amazon also has a wide choice of all sorts of lawn blankets.
Brands like Amturf and Grotrax have blankets with seeds ready-embedded. These come in easy-to-use rolls, that you simply unroll across your lawn until the desired area is covered.
If you want a biodegradable seed mat that comes without seeds, try Ecoseed’s erosion control blanket, and Takefuns has an eco-friendly mat that’s made from biodegradable paper. There are other options like good old-fashioned burlap.
Be careful when you’re buying online, as it’s not always clear whether the lawn blanket comes with seeds or not.
We’ve mentioned “biodegradable stakes” a few times. What are these, and where can you buy them? Again, try your local home stores and garden centers. Amazon has stakes from brands like Smart Spring. Just bear in mind that it takes time for these strong stakes to break down (at least two years in some cases); so if you want the stake out of your lawn, use conventional ones and take them up once the grass is established.
If certain patches of your otherwise healthy lawn have died off – or you want to plant a new lawn that grows in a uniform way – then a lawn seed blanket is definitely what you need.
Not only are they simple to use and helpful in stopping soil erosion, but as they’re biodegradable you don’t have to remove them and they’ll just rot down organically.
We’ve got several areas of lawn where the grass has been killed by ants nests, so I think this is well worth a try in my own backyard.
Hi, I’m homeowner and property investor Larry James. I founded Take a Yard to bring you the very best outdoor living content. Read More >
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