SRM–Red — The secret weapon of great tomato growers

Last Thursday's New York Times Garden Q & A by Leslie Land touched on the somewhat mysterious properties of red plastic mulch, considered by some gardeners the secret to seriously great tomatoes.

Here's the actual exchange:

Q. I keep hearing about using red plastic mulch to improve tomato production. Will it work under unstaked plants, which cover their mulch by midsummer?

A. You are hearing about SRM–Red [above], a reflecting sheet mulch.

The far red light it reflects tells tomatoes that they are being crowded by competitors.

The plants respond by growing larger and fruiting more.

The tomatoes, which can also sense the light, get bigger and more enticing.

But it only works if the mulch stays uncovered and keeps reflecting thoughout the growing season.

"Plants need a constant reminder," said Michael J. Kasperbauer, the lead researcher for the joint Agriculture Department adn Clemson University team whose experiments in the 1980s are cited by so many red mulch sellers.

The more far red light the fruits receive, the stronger the effect, he said, so the mulch works best when tomato plants are pruned and staked.

Sources include Abundant Life Seeds (abundantlifeseeds.com; 541-767-9606) and Peaceful Valley Farm Supply (groworganic.com; 888-784-1722)