How to Transplant Tomato Plants

Transplanting tomato plants (Lycopersicon esculentum) into rich, moist, well-drained soil provides good growing conditions for these tender fruiting plants. Perennial in U.S. Department of Agriculture plant hardiness zones 10 through 11, tomato plants are usually grown as annuals. Seed is sown indoors six to eight weeks before the final average local frost date in areas that experience frosts, and seedlings are hardened off before transplanting outdoors. You can also buy older tomato plants at garden centers and nurseries.

The best time for transplanting tomato plants is when temperatures are continually well above freezing. These plants grow poorly and can develop disorders if exposed to cold air and soil. Transplant tomato plants when nighttime temperatures are consistently higher than 45 degrees Fahrenheit and daytime temperatures are higher than 60 degrees Fahrenheit.

Harden off tomato seedlings and plants raised indoors for one week before planting them outside. Water the plants only when the soil surface is dry to a depth of 1/2 inch, and don't apply fertilizer.

Soil high in organic matter promotes good growth in tomato plants. If your garden soil is poor or average, spread a 4-inch layer of rich garden compost or well-rotted manure over the planting site one week before transplanting your plants. Dig the organic matter into the soil to a depth of 8 inches with a garden fork.

Tomato plants produce the most fruit in soil with a pH of 6.0 to 6.8 but tolerate a soil pH as low as 5.5. Home soil test kits give the soil pH and advise how much sulfur or dolomitic lime to add to the soil to lower or raise its pH, according to the test results.

Tomato plants grow roots from their stems, and burying the stems to the lowest leaves provides large, healthy root systems. This applies to older plants as well as seedlings.

Dig a hole as deep as a tomato plant root ball and its stem to the lowest leaves, and twice as wide as the root ball. Place the plant in the hole. If transplanting tomato plant seedlings, handle them by their leaves, not their stems. Scoop the dug soil into the gaps around the plant until the hole is full. Lightly press the soil around the tomato plant stem to firm it in, and water the planting site thoroughly until the water puddles on the surface. Plant the other tomato plants in the same way.

Regular fertilizing and watering encourage strong growth in tomato plants. Fertilize newly transplanted tomato seedlings and older plants with a soluble fertilizer formulated for transplanted plants. Dilute the fertilizer at a rate of 1 teaspoon per 1/4 gallon of water, and apply the solution an hour or two after planting. Apply the solution again after two weeks, and again two weeks later. Manufacturers' instructions vary from product to product. Check the label and follow the advice.

Spread a 2-inch layer of compost, leaf mold or other organic mulch around the plants after transplanting to help conserve the soil moisture. Water the plants when the soil surface is dry. Pull back some mulch to check if you aren't sure.