April 3, 1998

After a lot of back-and-forth e-mail discussion this past year, I decided to pursue a couple of experiments which will test some of the tenets of my usual tomato cultural practices.

Experiment One

It has been a long-established practice for tomato gardeners to strip all the lower leaves from their plants at transplanting time. These plants are then buried so that this section of the stem is also underground, whether by setting the rootball down deeper than usual, or laying the roots and stem lengthwise (a practice known as trenching). The idea comes from a tomato plant's ability to sprout roots along any buried length of stem. The more roots the plant can grow, the faster it will grow - or at least that's the idea.

I've been a bit skeptical about this. I imagine this probably developed because most people buy their tomatoes as transplants, and purchased transplants are almost always root-bound. In that specific instance, removing leaves would help by lessening the water demand placed on the inadequate root system. Burying the stem would, in that particular case, allow the plant to grow a larger root system faster, bringing itself back into balance (above and below ground) more quickly. However, it seems to me that a well-grown tomato plant, whose roots fill the pot to the proper degree, would probably be set back by doing this. This is a very well accepted and common practice, though, and I've gotten a lot of disagreement when I speak against the "true doctrine".

What I am doing this year is growing four sets of tomatoes. Sets one and two are pairs of Oroma tomatoes, while sets three and four are pairs of Bellstar plants. Within each set, the plants were started the same day and have been treated identically.

When the time comes to transplant them out, one plant of each set will be stripped of most of its leaves up almost to the tip, and then planted by laying it horizontally in a trench (to avoid our Pacific Northwest cool soil from affecting the experiment, I don't want to transplant them deeper). The other plants will be transplanted in my normal manner, with the plant set into the ground at the same depth it was growing in the pot.

I will let you know if there is a difference in yield or in the timing of the first harvest.

Experiment Two

This one is a bit more specific to the Pacific Northwest, but should be of interest to anyone who pushes the tomato season with various climate-modification schemes.

I am in the habit of going for the earliest tomato harvest possible. My usual practice is to raise the tomato plants under rather cool conditions (so they can handle sub-optimal temperatures) and set them out early under a cloche or PVC hoophouse. My harvests do start very early, but I have been getting curious as to whether the plants and/or fruits are affected by this.

This year I started a few tomatoes at the usual time, which is the first week of March. I held off starting the main crop, though, for another month (a bit extreme, but for the test it seemed like a good idea). Obviously the first group will be ready to transplant quite a bit earlier than the second group.

The early group will be raised in my usual manner, and will be set out inside a hoophouse in mid-to-late April. Group two will go out when it has sized up, which I imagine will be around mid-May. They will also go under the hoophouse.

What I am curious to see is whether the tomatoes from the early group, which will have seen colder temperatures in all likelihood, yield less than the tomatoes from the second group. Also I am planning on comparing the taste between the two sets.

To keep the number of plants fairly low, experiments one and two will overlap. Among the early group are two Bellstar and two Oroma plants. In the late group are also two of each variety. Of course there are other varieties as well, but they will not be included in the taste test.

To satisfy the statisticians in the audience: I realize that four sets does not comprise a Gaussian distribution, but I am not after hard numbers. If the differences observed in either experiment are too small to see in a limited sampling, then they make no practical difference. If the differences are large, though, they should show up even in a small experiment like this one.

The results of these experiments are discussed in the article Two Tomato Experiments - Results.

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