A tomato left to rot in the garden last summer resulted this spring in my eating ripe homegrown heirloom tomatoes by Memorial Day instead of the normal harvest time around the Fourth of July. A fruit dropped in mulch sprouted in October rain, did nicely through winter storms and then, with some watering since May, the vines have been yielding what I've decided must be Cherokee Purple tomatoes for going on a month. In terms of flavor, they're not Black Krims. No other tomato is. The word online is that Cherokee Purples rival Brandywines. That is true.

In other words, they're good enough that, with heirloom tomatoes of this quality costing $3 a pound in farmers markets, I thought I might be on to manna for readers. So I rang UC Davis' C.M. Rick Tomato Genetics Resource Center to ask why every gardener in Southern California doesn't plant tomatoes with their poppies -- in the fall. Director Roger Chetelat's response boiled down to two words: disease and pestilence.

Evidently, allowing plants, including volunteers, to over-winter offers viruses and insect predators safe harbor and is not to be encouraged. Instead of getting a head start, you could be ensuring the loss of your crop.

I took his point, but I was more chastened by the realization that I had been eating well out of dumb luck. I had no idea what my plucky little vines were going to yield, and I watered them on a gamble. Nursing volunteers from fallen fruit or the compost pile in years past has produced some real duds, mainly flavorless approximations of the plum tomatoes used by the canning industry.

It's the genetics, Chetelat explained. Keeping reading for more ...