Tomatoes are one of the most popular vegetables grown by home gardeners, indoors or out – and for good reason. Once you have tasted a freshly picked tomato that you have grown yourself, what lurks in the produce section of the supermarket completely loses its appeal. Given the amount of light and heat tomatoes require, growing tomatoes indoors for at least part of the season makes perfect sense – and in some climates, growing them indoors exclusively is the only way to ensure that they ripen at all. Unfortunately, growing indoor tomatoes can be a bit tricky to grow due to pests, diseases, and their need for consistent warm temperatures. However, with some planning and care, you can harvest an abundant crop of tomatoes indoors.
Tomatoes prefer to be grown at temperatures between 65°F and 85°F (18°C and 30°C). Growth slows down and the fruits stop setting when temperatures are either below 50°C (10°C) or above 95°F (35°C). The tomatoes themselves will remain alive when the temperature approaches freezing, but the plant won’t grow any longer, and developing fruits will be stressed and may start to look a bit peaky. Tomatoes do best when the days are longer, and when placed in full sunlight, or at least the brightest spot available. However, it is possible to grow them in the complete absence of sunlight, if you have good grow lights, and you are extra vigilant about the temperature.
Another important thing that indoor tomatoes need is good air circulation, to help prevent the growth of fungi. Unless you’re planting a seriously dwarf variety, it’s best to space the plants at least two feet apart. Speaking of varieties, there are quite a few bred especially for indoor cultivation, which is the best bet for a beginner because most outdoor tomato varieties don’t do well indoors. Whatever you choose needs to have disease resistance as a prominent feature. Another big thing to decide is whether to go with determinate or indeterminate varieties. Indeterminate tomato plants have growing tips that can grow indefinitely, and need a lot of root space. Determinate tomato plants are bred to be compact, need less root space, and will stop growing when the growing tip produces flowers. What you choose will depend on how many tomatoes you want, and the dimensions of your growing space.
Indeterminate plants produce significantly more fruit per plant, but they do vine like crazy, so you will need some sort of vertical support. They can be trained to grow up a string, though you have to be carful to prune them to one growing stem. Determinate plants don’t really need much in the way of support, and can get quite bushy, but they don’t produce nearly as many tomatoes. Of course, neither type will produce fruit without pollination which, in the absence of outdoor pollinators, you will need to do with a soft-bristled paintbrush, or even by gently tapping the flowers with something like a pencil. All of this may seem like a lot of fuss, but the triumph of picking your own ripe tomato is well worth it!