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does soil solarization kill weed seeds

First hack down the tall vegetation with a sickle, power trimmer, etc. But before doing so, make sure you know how to identify poison ivy, poison sumac, etc.

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.


Run a mower over the land to reduce the weeds’ height further. Now that all the weeds are as short as possible and the stumps have been removed, rent a large tiller to uproot all the weeds. Since this plot of ground is uncultivated soil, you will need a tiller that has some power: Do not undertake this task with a small garden cultivator! Allow the tiller’s tines to dig deep enough into the ground to loosen the weeds, so they can be removed—roots and all, if possible.

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.

Step One – Prepare The Beds – Till the garden area that you are wanting to solarize, removing any debris, such as rocks, compacted soil clots, roots, and anything else that doesn’t belong. Rake the area until you have a smooth and level surface. Next, water the area until the soil is about 70% saturated at least two feet below the surface. Preferably, the soil should be moist but not soaked for the solarization process, but there will be some time for the water to seep deeper into the ground as the next steps are completed. Moisture will help heat penetrate the ground easier, and moist soil issues are better suited to solarization in a moist environment.

Step Five – Plant Right Away – Planting and growing a new group of crops in your freshly solarized beds is important for multiple reasons. Firstly, you will avoid re-infestations of weed seeds that might find their way back to your new and improved bed. Secondly, you will begin to rebuild organic matter levels and fix the nitrogen and other nutrients for subsequent growing seasons.

Length of Time and Location

Soil temperature gardening techniques, or soil solarization, is the process of utilizing heat energy from the sun, to heat up the soil to levels that will reduce the effects of soilborne diseases and naturally eliminate pests, weeds and other soil problems. Soil solarization can be an effective option for treating your garden’s soil for a multitude of issues. Soil solarization works well in any type of garden, be it vegetable, flower, or herb intensive, and can help treat in-ground garden soil and raised beds alike.

The basic premise behind soil solarization is to lay out plastic sheeting over the plot of land that you are attempting to purge. The plastic sheeting uses the sun’s heat to raise the soil temperature to a level that will kill weeds, pests, and diseases. When executed correctly, the soil should reach temperatures of 120 F (49 C) or higher, which easily wipes out any soil-borne diseases or garden pests that have been plaguing your gardening efforts.

One common mistake that gardeners make when attempting solarization is using the wrong type of plastic. Black plastic seems like the wisest choice, as the color black is known to draw the sun’s rays. However, black plastic does not sufficiently heat the soil underneath as well as clear plastic, which allows sunlight to pass through more easily, more efficiently heating the soil underneath. Using clear plastic is essential to heat retention. Thin plastic sheeting is also recommended, no more than 1 to 2 millimeters thick, as it allows the sunlight to penetrate the plastic more easily in order to heat up the soil underneath.

Now, have your car windows tinted. Repeat the process and compare the air inside the car to the air outside. What happens? Even though the surface of the car heats up the same both times, the inside of the car gets far hotter when its windows are clear (similar to clear plastic) than when they are tinted (similar to black plastic).

To make the process even more effective, spread a second layer of plastic over the first. Use planks of wood or bricks to create a few inches of air gap between them. Research shows that the second plastic layer raises soil temperature another 2 to 10 degrees.

This is an excellent way of getting rid of grass where you would like to plant something else.

After solarization

When the lawn is dead, you have a few options. Clear away dead grass where you plan to put walkways or otherwise need an even surface. Where the lawn is to become planting bed, just treat the dead stuff as compost. Plant into or mound soil atop it. Eventually, it will disintegrate either way.

The process, which is called solarization, uses the heat of the sun’s rays to literally cook plants, weed seeds, nematodes, insects, and soil pathogens (the “bad guy” fungi, bacteria, etc. that bring diseases to plants) in the uppermost layers of soil.It also makes nutrients more available to plants later grown in solarized soil.

Since solarization works best in the upper foot or so of soil, don’t rototill the soil after you are done. (Actually, it’s best not to rototill ever. Rototilling, or turning the soil deeply, brings seeds and pathogens to the surface where they will proliferate.)

This is the “greenhouse effect.” Clear glass and clear plastic trap the heating power of the sun’s rays. That’s why soil beneath clear plastic heats up more than soil beneath black plastic. Adding an air gap and a second layer of plastic heats the soil even more.