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how to get rid of weed seeds in soil

Perhaps you are wondering at this point, “Why do I need soil solarization? Why can’t I just lay landscape fabric at this point, punch some holes in it, plant my new plants and then cover with mulch?” Well, the reason you can’t is that your job of killing weeds has only just begun. Weed seeds that you can’t even see are lurking beneath the surface, just waiting to sprout. If the weeds are vigorous enough, they will find a way back to the light (remember, the integrity of the landscape fabric will be compromised when you punch holes in it for your new plants). So you need to kill those seeds before you proceed with laying landscape fabric. And that is a job for soil solarization.

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.”

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

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.

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.

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.

Of course, if you use an organic mulch (such as a bark mulch), it will eventually decompose anyhow, becoming fertile ground for weeds. What can you do? Well, you had better keep new weeds pulled, faithfully. Vigorous roots pushing downwards can stress landscape fabric and breakthrough. On the bright side, these weeds should be relatively easy to pull, since mulch is a lot looser than dirt, and weed roots will not become impossibly entrenched.

Heat treating weedy compost destroys many of the microscopic life-forms that give compost its punch, so it’s a good idea to reprocess cooked compost for two to three weeks before using it in the garden. Place it in a plastic storage bin with a handful of earthworms borrowed from your garden and it will soon be laced with humic acids and other plant-pleasing compounds.

Most spacing recommendations, however, are based on the assumption that adjoining plants will barely touch when they reach mature size, so stick with the guidelines when working with plants that are prone to foliar diseases, such as bee balms (Monarda didyma and cvs., USDA Hardiness Zones 4–9) and phloxes (Phlox paniculata and cvs., Zones 4–8).

Monday: Kill weeds. Tuesday: Kill weeds …

If you choose to use this method on seldom-dug areas, such as the root zones of shrubs and trees, opt for tough landscape fabric for the light-blocking bottom sheet. There is a catch, however: As soon as enough organic matter accumulates on the landscape fabric, weed seeds dropped by birds or carried in on the wind will start to grow. For the bottom layer of fabric to be effective, these must be pulled before they sink their roots through and into the ground.

Does 32 ounces of vinegar mixed with 1/4 ounce of soap sound like an accurate mix

Great tips! Another one is to mow your lawn 3” or higher. This will help provide a better environment for the
grass and a less desirable environment for weeds, resulting in a greener,
thicker lawn. http://grasshopperlawns.com/weed-control/

While weeding, try to hold the trowel vertically (like a child holding a crayon) to eliminate strain on your wrist.

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.

5. Hoe Them Down

Image: Straw used as mulch to suppress weeds, hold in moisture, and break down into soil. Credit: Jurga Jot/Shutterstock

Encourage weeds to grow before you plant your garden. Lay sheets of clear plastic over your garden in early spring to warm up the soil and encourage weeds to germinate. Once the weeds are several inches above the soil, pull or hoe them out. Then plant your own crops.

Some folks say it helps to weed at night! No kidding. Research indicates that weeds may be stimulated to grow by a sudden flash of light, which is what you give them when you turn the soil over during the day. A German study concluded that by turning the soil at night, weed germination could be reduced by as much as 78 percent! You can try this method by working under a full Moon, or at dawn or dusk.