writes:

No, not 'coffee cans'. See: http://www.wallowater.com -
the pictures are TERRIBLE quality unfortunately. Here's a
better picture of a similar thing:

http://tinyurl.com/gseq

The ones shown above are red, the actual WalloWaters (at
least mine) are green.

Our tomato guru, specializing in heirloom veggies (over 100 varieties of
tomatoes), told us that the red Wall of Waters are best. He gave a
detailed explanation about studies done on the light rays, etc., and said
the results of the research was that the red was more effective than the
green. I didn't bother to remember the reasons, just that it was. I have
total faith in Michael; he's been growing and selling commercially for
years and "knows his stuff" and does thorough research on everything he
does.

However, whichever ones are used will give a tremendous head start to the
grower, or so I'm told by those who know and have used them. Mine have
done so well in past years that I just "rough it" with my freshly mown
grass mulch. :-)

Glenna