Growing the Desert Garden

Welcome to the Desert Garden, with garden coach Tyler Storey, where we talk about everything having to do with gardening and landscaping in the Desert Southwest. From composting to Cercidium and agaves to arugula — we'll cover everything you want to know to grow your own beautiful Desert Garden.

Saturday, May 3, 2008

Back at the Ranch: Tomato Fruit Set

New tomato © Tyler StoreyThe first known tomato of the season! Right there in the middle; the little green thing. I spotted this perhaps one-quarter inch long green tomato a couple of days ago and it's now up to about three-quarters of an inch and joined by a multitude of companions. This particular variety is an experiment, a variety called "Sausage" that I hadn't tried before. I started them indoors from seed purchased from the Victory Seed Company (, which specializes in open-pollinated and heirloom garden seeds, then moved them out to the garden when the weather was sufficiently warm.

Sausage is a paste-type tomato which has several attributes that suggested it was worth a test. First, it's a short-season tomato, listed at 70 days, which is always good for the fast-moving seasons in the Desert Garden. It's also an indeterminate variety, meaning it will continue to grow, flower and set fruit as long as the weather allows; generally until temperatures are consistently above 90 F and the pollen is no longer viable. Considering the vagaries of weather in the Desert Garden, we should appreciate any vegetable that is willing to try and fail, and yet try again.

Indeterminate tomatoes are also called "vining tomatoes" because of their sprawling habit; this is a bonus because it means much of the fruit will be shaded under the vine, and somewhat protected from the Desert Sun. The slightly elevated humidity under the canopy of the plant will also help keep the tomatoes' skin from cracking as they ripen. And, last, the catalogue description used the words "interesting," "unusual," and "flavorful" so I had to at least try it.

The time immediately following fruit-set is critical in developing good tomatoes, as it is for any fruit. After pollination and fruit-set, fruit undergo a fairly short period of rapid cell division, followed by a much longer period of cell expansion. The cell division period in tomatoes lasts only about a week, while the cell expansion period is 6 weeks or so. There's all sorts of fascinating chemical and hormonal things going on during this period, but what's really important is to realize that the ultimate size of the fruit is determined in that first week; only the cells that develop then will have the chance to expand later.

On a practical level, what that means is that we need to make certain that the tomato has steady, even moisture during that phase of cell division. If the tomato is drought-stressed during the cell-divison stage, no amount of later watering will make up for it. In the Desert Garden, the easiest way to do this is to lay a good layer of organic mulch on the surface of the soil around the plants. Mulch holds water in the soil and helps eliminate the fluctuation of wet/dry that occurs in unmulched soil.

Even moisture is important during the expansion phase, too, but right now it's critical. It's the difference between tomatoes that are apparently going to be interesting, unusual, and flavorful, and tomatoes that are simply not worth the bother.


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