Sharon McA. asks re solarizing soil with black vs. clear plastic:
>> Anyone have experience to report from other climates? I realize
>> southern NM qualifies as extreme
Sure does! In cooler places, the clear plastic is preferred because it gets
the soil much hotter (sun goes through clear plastic to soil, heat trapped by
plastic; black plastic absorbs sun's rays and transmits radiant heat to soil
radiantly). For solarizing to be most effective at killing weed seeds and
disease and pest organisms, you wet down the soil (wetter than you would get it
for growing), seal the edges of the plastic around the bed, and leave it for
four weeks or so during a dependably sunny time of year. It's sort of a 'steam
cleaning'; the temperature should get up to about 160-180.
The practice, developed by Israelis and now tested and taught by U.S. ag
schools, has helped check fusarium and verticillium wilt in beds for tomatoes,
and I bet it could help prevent leaf spot in irises (by reducing the number of
offending soil-borne organisms), as well as severely reducing the weed problem.
Nell Lancaster, Lexington, VA firstname.lastname@example.org USDA zone 6b