Choose a cloudy, overcast day to move the plants outside permanently. If transplanting must be done on a bright day, plant late in the day and shade the plants for a few days. If the weather is cold, gain additional warmth from solar heat-collecting water caps. Gallon milk containers filled with water and placed near the plants will collect heat and disperse it overnight. A paper bag will help break the wind, but black roofing paper will attract the heat and break the wind. Bushel baskets can be overturned and placed over the tender plants, too.
When tomatoes bloom, spray the flower clusters twice a week with blossom set spray, which contains a hormone that will help the fruit set as early as possible. Side dress the plant with fertilizer after the plant has blossomed.
Why didn’t we start our tomatoes in January and get a really good head start on summer? Growing tomatoes indoors is timed precisely because tomatoes can’t stand being in the house any more than you can. By starting them this month, they’ll be perfectly grown and ready to transplant outdoors at the earliest possible date, having had the advantage of a few warm weeks in your house. They’ll be far ahead of any plants started outdoors from seed in May in the still very cold soil. You’ll be sick of watering, moving, turning and tending those tiny pots, but you’ll be so glad you did it.
Start with one of the early varieties, such as Early Girl or Big Early. Plant seeds indoors about 10 weeks before the average last spring frost date for your area. Re-pot the tiny seedlings when they are 3 to 4 inches high. At this time, pick off all the lower leaves and replant up to the leaves. Re-pot again when the plants are 8 to 10 inches high, again pinching off the lower leaves to prevent rotting.