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New Mexico State University

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Get Head Start on Vegetable Garden with Transplants

LAS CRUCES -- In New Mexico, home vegetable gardens are actually three gardens in one: a spring garden, a summer garden and a fall garden. Planting dates for the gardens depend on the hardiness of the vegetables planted and the length of time the plants need to reach maturity.

Gardeners can manipulate planting dates and give vegetables a head start by starting seeds indoors, then transplanting the seedlings into the garden, said a New Mexico State University horticulture specialist.

"Cole crops like broccoli, cauliflower and cabbage that are planted from seed in the spring will mature in hot weather," said George Dickerson, with NMSU's Cooperative Extension Service. "The hot weather often burns plants and makes them taste bitter."

To avoid these problems, Dickerson suggests using transplants to establish cole crops in the garden.

"Tomatoes also perform well as transplants," he said. "Tomato seeds are often quite expensive, so transplants are the most efficient way to make sure every seed develops into a plant."

For healthy transplants, Dickerson recommends purchasing from a retail nursery. "However, if you want to grow an heirloom-type tomato, you may have to grow your own transplants."

To begin transplants as seeds, find a suitable location indoors in flats or other containers, or outdoors in cold frames or hotbeds. Plant seeds six to eight weeks before moving them into the garden.

Use a disease-free growing medium. "A well-balanced, synthetic soil mixture from a local nursery will limit disease and weed problems," he said. Plant seeds in trays, flats or individual plastic or peat pots. Individual soil pellets also can be used to start seeds.

"The biggest problem with home-grown transplants is not enough light, Dickerson said. "Transplants require eight or more hours of direct sunlight or else they become tall and leggy." If necessary, supplement direct sunlight with light from fluorescent bulbs suspended 6 to 8 inches above the seedlings.

Most vegetable seeds germinate well at daytime temperatures of 70 degrees and nighttime temperatures of 60 degrees. Plants grown in flats or trays can be transferred to individual pots as soon as they develop true leaves.

Allow at least 2 inches between pots for good air circulation and to prevent shading.

"Whether you purchase or grow your own transplants, they must be hardened off before planting them in the garden," he said. "Hardening off simply means setting the plants outside in the shade for a few hours each day to help them adjust to the outdoor environment." Withhold water gradually and transplant to the garden after four to six days.

Water plants just before transplanting to keep the roots from drying out. This also will make removing plants from plastic pots easier. Transplant in the evening when it's cool to give plants time to adjust to their new environment before confronting the sun the next day.

"The garden soil should be moist when transplanting," Dickerson said. "Pat down the soil around the transplant and water immediately." For transplants in peat containers, plant deep enough to cover the top of the pellet, cube or pot. If the container top is left exposed above the soil, it will act as a wick and dry out the plants.