Soil Solarization & Bake Out Pests With the Sun

Soil solarization is a chemical-free way to disinfest soil using the sun. You spread clear plastic film tightly over moist, tilled soil during the hottest months and leave it for four to six weeks. The trapped heat raises the top 10–15 cm of soil to lethal temperatures that kill weed seeds, soil-borne fungi and bacteria, and nematodes.

Plastic area = field area × (1 + overlap%). The overlap covers the edges you tuck and seal into the soil and any sheet-to-sheet joins, typically 10–20%. Divide that area by the roll area (roll width × roll length) to get the number of rolls, and multiply the area by the film's gsm to get the film weight in kilograms.

Use transparent (clear) film, not black. Clear plastic lets sunlight through to heat the soil and traps the long-wave heat radiating back up, like a greenhouse, so the soil gets hottest. Black plastic absorbs heat at the surface and is better as a weed-blocking mulch than as a solarizing film, which heats the soil much less.

Four to six weeks of clear, hot, sunny weather is the usual target. Shorter periods may not reach lethal temperatures deep enough; longer is better in cooler or cloudier spells. The calculator lets you set the period in weeks so the timing matches your climate and the depth of pests you need to control.

Moist soil conducts heat far better than dry soil and the water itself helps kill organisms, so wetting the bed before laying the film is essential. Irrigate to field capacity just before covering. Damp soil moves the heat deeper, weakens resting structures of pathogens, and makes weed seeds and nematodes more vulnerable to the high temperatures.

Till the soil fine and level, irrigate it well, then roll the clear film out tightly with no air gaps so it lies close to the surface. Dig a shallow trench around the edges, tuck the film in and bury the edges with soil to seal them. A tight, sealed sheet traps the most heat; loose or torn film loses it.

It targets the top 10–15 cm of soil and kills many weed seeds, soil-borne fungal pathogens such as Verticillium, Fusarium and Sclerotium, several bacteria, and plant-parasitic nematodes. It works best on organisms near the surface; deep-rooted perennial weeds and pests below the heated zone can survive and may need other measures.

During the hottest, sunniest, longest days of the year — typically the peak of summer — when the field would otherwise be fallow between crops. The stronger and longer the sunshine, the higher the soil temperature and the more effective the treatment, which is why mid-summer fallow periods are ideal for solarization.

Yes. Solarization works on open field beds, nursery seedbeds and the soil inside polyhouses and greenhouses, where the enclosed air makes it even hotter and faster. Just enter the actual area to be covered; the calculator gives the film, rolls and weight whether the surface is a large field or a few nursery beds.

They are reliable planning figures for film quantity. The plastic area, rolls and weight are straightforward arithmetic, but real material use depends on field shape, how much you overlap and bury, and offcuts. Buy a little extra to allow for trimming and sealing, and treat the period in weeks as a weather-dependent guide.