How to Solarize Soil

Rid your soil completely of weeds, pests and diseases - without harmful chemicals. The process of solarizing uses the heat of the summer sun to raise the soil temperature high enough to kill the harmful organisms and seeds hiding in the soil.

Difficulty: Moderate

Instructions

Things You'll Need:

• Clear Plastic Sheeting
• Compost
• Garden Hoses And Attachments
• Mulch
• Rototillers
• Shovels
• Spading Forks
• Wood Mulch
• Compost
• Shovels

1. Determine what kind of soil you have (see "Check Soil Drainage"). Soil that is either too hard (compacted clay) or too sandy can be remedied by adding organic materials such as homemade compost, manure or shredded wood products.

2. Amend as needed (see "Choose a Soil Amendment). Lay a 3-inch layer of the organic matter over the soil and work it evenly into the top 8 to 9 inches of soil using a garden fork or a shovel. For soil that is extremely hard, dig down several feet to break apart the soil and layer in compost throughout the depth of the bed.

3. Till and level the intended area of soil. The bed should be at least 2 feet wide to limit heat loss around the edges.

4. Soak the soil thoroughly. This may take hours with a sprinkler attachment.

5. Cover the entire bed with a single sheet of 1 to 4 mm clear plastic.

6. Lay the edge of the sheeting in a trench and cover it securely with soil so no heat can escape.

7. Leave the plastic in place for a minimum of six weeks, clearing away debris and rainwater that may accumulate on the plastic and block the sun's rays. The longer the plastic cover stays, the greater the benefits.

8. Remove the plastic, and if there is still time left in your growing season, begin planting shallowly in the top few inches of soil. Save the sheeting to use again.

9. Spread a layer of mulch over the beds to preserve moisture, suppress weeds and continue to add organic material to the soil as it breaks down. Ground bark or homemade compost work well and should be laid 2 to 4 inches thick.

Tips & Warnings

• Although you will have to skip a planting season and start your beds from scratch, the pest-fighting benefits of solarization can last for years. The result: fungus-free and weed-free soil that is high in organic material and able to store the water, air and nutrients vital to a healthy garden.

on 6/30/2006 Solarization is a great technique for ridding soil of pesky pests and pathogens.

Solarizing pasteurizes the soil. So adding compost to the soil - with it's abundance of beneficial microorganisms - is a waste of time and good compost. Solarization will kill all the beneficial microorganisms in the compost.

Add the compost and any other amendments after you solarize the soil. In addition, do not plant this area immediately. Give the microorganisms a week or two to reestablish before planting.

Unless there was some really bad mojo going on under the plastic, six weeks is overkill. If you use this process during the peak of summer, two to three weeks will be enough to do what needs doing. This is especially true in hotter climates. Perhaps you folks in the colder climates will need an extra week or two if you don't get sun.

on 11/22/2005 I use worm casting for my watermelon plant. This year I noticed it grew faster - and worm casting holds the water better. Last year I tried different organic compost but worm casting is the best I've ever used. I notice the watermelon tastes better, too.