Just because the plants are small, you don’t need to plant them shoulder to shoulder. Crowding is a common problem with beginning gardeners and, with some gardeners, remains a problem. It is not uncommon to see three to four tomato plants growing where only one should have been planted. A tomato plant that has been allowed nine square feet of space will produce many more tomatoes than plants given only four square feet of growing space.
Plants such as tomatoes, peppers and eggplants need not only adequate amount of light for each plants’ photosynthesis but also adequate air circulation around the leaves, stems and fruit to minimize disease. When plants are crowded, they compete for light, water and nutrients. Crowding also prevents air from freely circulating through the foliage. Thus foliage and fruit stay wet longer, making conditions more favorable to disease. Crowded plants need more fungicides to control diseases.
–Crowding is also a problem with root crops such as radishes, carrots, beets, parsnips, salsify and turnips. It is difficult to sow carrot seeds thinly because they are so small. I find mixing the carrot seeds with dry instant coffee at a ratio of one part by volume of carrot seeds and four parts by volume of dry instant coffee allows me to sow carrot seeds that will require only minimum thinning. It is possible, but more expensive, to purchase pelletized carrot seed.
To grow good carrots, you must thin the seedlings at least one to one and a half inches apart. I generally thin carrots when they are approximately two inches tall, using a small triangular scrapper. Beets and parsnips should be thinned to approximately two inches apart. Waiting to thin the beets until they are six to eight inches tall will provide you with a nice meal of beet greens.
Never transplant radish, carrot, beet, parsnip, salsify or turnip seedlings, as transplanting will result in useless branched roots.