Tomatoes are thriving, vining plants when it's warm and sunny outside. In the spring, when it's still a bit cool, they require some protection. Spring is, however, the best time for planting tomatoes, as it gives the plants a long growing season for their fruit harvest.
University of Missouri Extension suggests setting tomatoes out in the home garden as early as possible in the spring, to give the plants time to grow and fruit before fall comes. The Extension suggests planting as soon as the last frost is gone, when soil warms enough for easy working.
The Tomato Gardening Guru website advises that cool, cloudy days are best for transplanting tomatoes into the home garden. Gardeners should plant in the morning, to keep tomatoes from drying or suffering during the process.
Any planting should start with adequate preparation, to keep the transplant process quick and easy. Tomatoes require a site that gets full sun all day and quick drainage. Gardeners should mix a combination of half quick-draining soil and half organic compost, with an addition of starter fertilizer, into the soil a day or two before the transplant.