Solarizing soil in fall doesn’t work before planting wildflowers
Q: I read about sowing a perennial flower garden in the fall for spring blooms. They said to first cover with plastic to kill all grass and weeds.
A: I don’t think covering with plastic does any good in fall. Solarizing soil requires a couple weeks of very hot sunny weather. You don’t get that in the fall.
I guarantee weed seeds in the cleared area will sprout alongside your wildflower seeds. It is imperative that they be removed before they grow large. How will you tell the difference between weed and flower? The weeds have to be pulled by hand so plan on having some steppingstones in the area to stand on while you work. Plan on thoroughly weeding every week, even in winter, to keep competition at bay.
More details at Planting wildflowers