Jack Schmidling wrote:
Marilyn was reading some off-the-wall hype about how red plastic mulch
under tomatoes will make them grow better and faster. I, of course,
dismissed it as nonsense.

Your comparison is skewed, you are making your unmulched plants
compete with weeds. I would suggest had you kept your unmulched
plants cultivated of weeds they would have equaled or surpassed the
plants surrounded by red plastic sheeting. Actually any medium that
prevents air and moisture from penetrating does not qualify as mulch,
that's simply a plastic barrier. I would also suggest that since your
red plastic is not in direct contact with the ground it also does not
qualify as mulch. You should be embarrassed to present your weed
patch as a vegetable garden.