While many people grow the average round tomato, growing square tomatoes can be impressive. According to the Texas Cooperative Extension, tomatoes are the most popular vegetable to grow in America. Other square fruits, such as watermelons, are grown overseas, and the methods used there can apply to tomatoes. While commercial growers are experimenting with square tomatoes, to make the vegetable more convenient to store and ship, the home gardener can grow these novelties for fun.
Select a type of tomato that produces fruits that are not too small; medium or large fruits are best. Varieties like Big Boy and Celebrity are commonly available in garden centres.
Plant the seedling outdoors after all danger of frost has passed. To do this, dig a hole in the garden soil and add the tomato plant. Add soil back around the roots of the plant and pat the soil gently in place.
Support the tomato with a tomato cage or other structure.
Care for the tomato plant. Give it about two inches of water per week and feed it with a 10-10-10 fertiliser about once a month. The plant should get sun for at least seven hours a day.
Choose or construct a square box to grow a single tomato in. Consider what size the tomato will eventually be to avoid a box that is too big or too small. At least one side of the box should be removable and have a hole in it for the stem. You will need to be able to slip the stem into the hole after the tomato has started to develop, so the hole must be connected to a slit in the removable lid. The box should be made of sturdy material like Plexiglas or wood.
When the tomato is about halfway grown, carefully put the box around the tomato. Let the stem come out through the hole in the top, and be sure to not pluck the unripe tomato in the process.
Make sure the box is adequately supported so that it does not pull the plant down. Use wire or cord to help secure it to a trellis or tomato cage.
Remove the tomato from the box once it is ripe.
It is best to select a type of tomato you have grown before so you can anticipate how big it will be and know when the proper time is to put it into the box. If making a box from scrap plastic or wood, add hinges so the box can easily come apart once the tomato is ready to harvest. Kits are available for those who do not want to make their own boxes. Some garden centres offer them, and they are also available online.