Like many gardeners, I spend a lot of my summer weekends staring at my tomato plants wondering what is going on.
Lately they have been teasing me. They produced a couple of beauties, ripe luscious Cherokee Purples. Last week, I devoured them.
But then, like a spurned lover, the tomato plants stopped delivering joy. They seem to hold back, waiting for me to make some move. Green fruit torments gardeners, but especially ones who have already tasted bliss.
So as I cast about tomato literature looking for solutions to my reluctant plants, I came upon the red mulch tactic. The idea is pretty straightforward. Placing red plastic sheets, a product called SRM-red, underneath plants changes the way light bounces off the ground, and that promotes plant growth and ripening.
Although the red mulch theory has been around for sometime, it was news to me. I plowed through a few articles in scientific journals about this before I found a piece in Agricultural Research magazine written in language I could understand. Then I called Michael J. Kasperbauer and Patrick Hunt, researchers who conducted many experiments with wavelength of light and plants at the U.S. Department of Agriculture's Plains, Soil, Water and Plant Research Center in Florence, S.C.
Kasperbauer, who is retired and living in Lexington, Ky., talked about phytochrome, a plant protein that reacts to red and far-red wavelengths in light. I tried to keep up with him but got lost several times.
The one concept I could get my head around was that the light waves bouncing off colored plastic amounted to "fooling" the plants into behaving as if they face stiffer competition for sunlight. Kasperbauer told me that while this notion was correct, it was extremely simplistic. I told him I was a pretty simple guy.
His colleague, Hunt, told me that once I start playing with light and the effect reflected light has on plants, I was in for "a lot of fun."
He said composition of light, the wavelengths that bounce off various colors of plastic, is as important as the quantity of light a plant receives. Potatoes seem to favor pale blue light, turnips prefer orange, he said.
This was pretty esoteric stuff. But what I also heard them say, over and over again, was they grew big tomatoes, and a lot of strawberries, in their research plots covered with sheets of red plastic.
I asked if another form of red mulch, wood chips that have been treated with red dye, would work. I asked because I have noticed that these bright red chips appear to be in vogue, the mulch of the moment, showing up on lawns and gardens throughout Maryland. Apparently some folks think that a flowerbed lined with red wood chips looks striking. Others think it looks garish.
Hunt doubted that dyed red wood chips would have the same effect on plants as the red plastic. Red wood chips are put down for decorative impact, he said. Plants, he said, are very discriminating about wavelengths and color. "Not just any red," Hunt said in 1991 article in Agricultural Research "is going to give you more and better tomatoes."
J. Kim Kaplan, who works for the USDA agricultural research center in Beltsville, wrote that article. In addition to writing about red plastic, Kaplan also tried the technique out a few years ago on the tomato plants growing in her Silver Spring backyard.
It worked, Kaplan told me in a phone interview, a little too well. The red plastic mulch helped to produce lots of tomatoes, which in turn attracted lots of deer from nearby Rock Creek Park. The deer demolished the plants, she said.
That, in my experience, is how things work in gardening. One solution often produces another problem.
I found a roll of SMR-red plastic on a gardening Web site, growerssolution.com. It cost $34 for 100 feet.
That is a little pricey for me. And it is a little late in the growing cycle to be putting down plastic.
It is easier in the spring, when you are planting seedlings. Maybe next year will be a red plastic mulch year for me.
If things don't improve at the garden in the next few weeks, I will fall back on a time-tested tactic for turning green tomatoes red. I will go on vacation. I bet that as soon as I leave town, a bushel of tomatoes will ripen.
rob.kasper@gmail.com