The advantage of plastic mulch is in cool weather. The mulch creates a greenhouse effect in the airspace between the mulch and the soil, warming the soil, and suppressing weeds.

This gives the starts fall growing conditions of "cool heads and warm feet."

I don't know how mulch afftects growth in high summer.

We used clear mulch to great effect in Fairbanks, AK. The colored mulches reflect a certain part of the light spectrum, thus enhancing the ripening of tomatoes.

Cheers,

Jim

I'm thinking the same thing for this year trying to get more heat for growth & ripening of tomatoes, cucumbers & squashes. For years in Kent my dad used the black plastic to preheat the soil in spring & as mulch with amazing results. He tilled in manures yearly in the fall & tilled again in spring before laying out the previous year's plastic if it wasn't too beat up.

I'm curious which type of mulch might work better than my usual organic matter over a few sheets of newspaper, cardboard, or burlap bags applied after soil warms (when tulip petals fall).

cover crops?
I read in an Organic Gardening magazine from the library Rodale's study about tomatoes with cover crops of rye & another grain produced the same results as black plastic & better even because it was water permeable.

If you use black plastic:
In summer cover with organic matter to reduce heat when temps are over 85. I've used thin layers of grass clippings, coffee grounds, hay sweepings, & other plant matter in abundance that time of year. It dried quickly for us on the plastic & you can layer more. I didn't use soaker hoses back when I used the plastic, but if I do it again I'm using soakers under the plastic.

Corrine