Every week from late April to the end of June, I see many people carrying tomato starts out of the Public Market that are two feet tall and blooming, sometimes even forming fruit, in “gallon” pots, sometimes even 4-inch pots. They obviously don’t know that tomatoes that are blooming in their pots will likely not grow much once they are put in the ground, or bear more than a few tomatoes, regardless of whether one cuts the roots and/or buries them up to their necks. Stranger things have happened in the garden, but ten years of professional gardening experience has shown that this is usually the case.
I usually don’t buy tomato starts in anything but 4-inch pots, and the plants in those pots cannot be taller than about 8″; if they are blooming, forget it. This year, when I first went looking for tomatoes at Bi-mart, their 4-inch stock was low, and not realizing how quickly they re-stock, I bought some “gallon” (6″ container) plants that did not appear to be blooming. The next day, I found that they had re-stocked, and I bought a batch of 4″ tomato starts. When I took a closer look at the “gallon” plants I’d bought, I saw flower buds beginning to form, so I decided to keep those plants and sell smaller ones to my customers. I pinched off the buds.
In general a small start will surpass a larger plant, but that has not happened this year; the barely-budding “gallon” plants are still ahead of the 4-inch, though not much in some cases. One of the gallons, an Oregon Spring, is growing phenomenally well, one of the biggest plants I’ve grown in many years. Apparently, “barely budding” in gallons is acceptable; the roots were not yet bound.
It is best to plant tomatoes at normal depth, not bury them up to their necks in an effort to grow a bigger root system from the stem. Burying them is stressful; their roots are deeper into cold soil; the stress causes the pests to target them; and their leaves are that much closer to the pill bugs, who don’t like to eat any higher than 6″ off the ground. A start that is not root-bound will grow a good root system without being buried. If the roots are wrapping around inside the pot at all, cut them so they will grow outward, not circle in the hole.
Warm soil is the other key to getting tomatoes, peppers, eggplant, basil, cucurbits, beans, and corn to grow well. If the bugs ate your plants, you planted too early; replant when the soil is warmer. My tomatoes and peppers didn’t go in the ground this year until mid-May, as the weather was chilly. I surround them with a few good-sized rocks to absorb warmth during the day and release it at night; warm night temperatures on the roots are most important.