In the Garden:
Northern California Coastal & Inland Valleys
After solarizing the soil, beautiful flowers such as this Agapanthus can flourish with fewer weeds and insects competing with it.
Cleaning Up the Soil
Sometimes the amount of weed seed, disease, and pests in the soil calls for drastic action. If your tomato plants are constantly suffering from attacks of virus, if you have a plague of nematodes eating the roots of your vegetables, or if you have noxious weeds that come back year after year, it may be time to start over. However, you don't have to dig out all your soil to begin anew. You can use the power of the sun to solarize the soil and bake it clean.
Steps to Solarization
Now is the perfect time to solarize your soil. Soil solarization should be done only as a last resort since it indiscriminately kills all living organisms in the soil. Once you have determined the soil needs an overhaul, clear out all the weeds and dead plant material from the area you wish to treat. Once the bed is clean, irrigate the soil thoroughly to a depth of 18 inches. Cover the damp soil with clear plastic sheeting, using bricks around the edges of the plastic to hold it in place. In a few hours, you will see condensation begin to form on the under side of the plastic sheeting. This means the process of sterilizing has begun. In a few days, you will see weed seeds begin to germinate under the plastic, but they'll die in the heat. As the temperatures under the plastic sheet increases, the weeds, seeds, nematodes, insect eggs, and everything else, including the good soil microbes will die.
Finishing the Process
Leave the plastic sheeting undisturbed for one full month. Remove the plastic, turn the soil to a depth of 18 inches with a shovel or rototiller, water and cover again with the plastic sheet. This step brings to the surface any organisms or seeds that were lurking deep in the soil.
At the end of the second month, remove the sheeting and add plenty of organic compost to the bed to reintroduce beneficial microbes into the soil. Turn the soil to incorporate the compost, water, and plant your fall garden.
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