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how to remove weed seeds from soil

Now you truly have a “clean slate” with which to work. Remove the plastic and lay down landscape fabric. You should try to use one of the stronger types of landscape fabric if possible, just in case—in spite of your best efforts—any sharp objects remain in the ground (which would puncture the landscape fabric).

If there are shrubs and trees present, cut them down with an ax or chainsaw. The ground needs to be smooth before you begin soil solarization (since you will be spreading plastic over it), so you will also have to remove the stumps left behind. If you are looking for a cheap way, use a tool called a “mattock.” Dig and chop your way with the mattock under the root-ball to access and remove the taproot. Warning: this is hard work and may be feasible only for smaller stumps.

When you cut slits in the landscape fabric and install new plants, be careful that you don’t get dirt all over the landscape fabric. After all, why prepare a home for airborne seeds? Sure, you will be applying mulch. But airborne weed seeds can wend their way through mulch particles. If they find dirt, then they are “weeds waiting to happen.”

Preparation

Now use a steel rake on the area that you have just tilled, wielding it like a fine-toothed comb to remove the majority of the uprooted weeds. Next, rake the area again, this time with the object of evening out the soil as best you can and removing stones, twigs, etc. The final preparation for soil solarization will require the use of a garden hose. According to the University of Idaho Extension (UIE), you should moisten the area that you have just raked to “conduct and hold heat, to stimulate weed seed germination, and to prevent dormancy of below-ground vegetative plant parts.”

Soil solarization is a preventive, organic method of killing weeds before weed seeds even sprout.   But the advice below is also meant for homeowners wishing to start a garden with a clean slate, reclaiming a patch of land where weeds have taken over, in such a way as to reduce to a minimum the hassle of future ​weed control. Want to transform a piece of land that has “gone to pot” into usable space? Then the method explained below may be the solution to your problems.

There is lots of work involved since soil solarization entails getting to the root of the problem, underground.   And we will not be taking the shortcut of using herbicides, so that means a bit more work. But if you do not mind getting your hands dirty, then let’s roll up our sleeves and begin stopping our weedy foes in their tracks.​

Cover the raked, moistened area with a clear polyethylene sheet. The edges of the sheet can be held down by cinder blocks to keep the plastic from blowing away. If the raking mentioned above was done diligently enough, there will be no sharp objects sticking up to puncture the plastic. The sheet of clear plastic can be anything from 1 to 6 mil. in thickness. In the Northern hemisphere, the best time for soil solarization is June and July, when the sun is at its peak. UIE recommends keeping the sheet of clear plastic tightly stretched out over the area for about 2 months. During that time, the sun will be killing weeds for you—”cooking” them before they have a chance to sprout. Plant pathogens will be killed, to boot.

While some folks turn to dangerous chemicals, many weeds are actually resistant to herbicides and respond better to different methods of control. See 5 natural “weed killers” to get rid of competing plants while still keeping people, pets, wildlife, and waterways safe.

Some types of weeds, especially those with deep roots, grow well because the soil is compacted. The plants roots aren’t getting the air, water, and nutrients they need so the weeds start to take over. If you rent an aerator from your local home improvement store, you’ll be amazed at how providing annual aeration will reduce the amount of deep-rooted weeds.

7. Chop Off Their Heads!

Note: If you use leaf blowers, many come with shredders that can turn yard debris into garden mulch fast, which saves you the costs of making or buying your own mulch. See our mulching guide.

When weeds have really sprung into action, nothing beats a good old-fashioned garden hoe with a long handle. Hoeing is best done in the morning when the soil is dry. The weeds will cut cleanly from the soil and this creates a “dust mulch,” which inhibits the germination of new weeds. You can let the weeds simply dry in the sun during the day and then take to the compost heap.

If you hoe, do not overturn the soil or dig down below the surface (no-dig). We don’t want to expose the dormant weeds seeds to light and air which will only bring them back to the surface.