Grow Vegetable Transplants During Winter

Home gardeners can get a jump on the growing season by starting vegetable transplants this winter in indoor containers or outdoors in cold frames or hotbeds.

By growing transplants, gardeners can save money while choosing the exact varieties they want. Nursery stock is often expensive, and buyers frequently must purchase four-pack containers rather than just one or two plants. Local nurseries may not carry varieties gardeners want, and often the variety purchased is not the one on the label because customers tend to remove labels to read them and replace them in the wrong container.

Start transplants six to eight weeks or more before setting them in the garden. For best results, begin with a disease-free, soilless potting soil mix. Mixes are available at most nurseries.

Moisten the soil and place in clean planting trays, flats, cut-down milk cartons or individual pots. Make sure the bottoms of all containers have drainage holes. Fill each container with soil mix up to a half inch from the top, then plant the seed following instructions on the package.

Most vegetables germinate well at a daytime temperature of 70° F (night, 60° F). Plants need at least eight hours or more of direct sunlight daily. Less light tends to make plants leggy. Direct sunlight can be supplemented with special grow lamps (fluorescent tubes) placed 6 to 8 inches above the seedlings.

Transfer transplants grown in flats to individual pots when the transplants have developed two true leaves. Lift a clump of seedlings from the flat and gently separate the seedling root systems, keeping only strong seedlings with well-developed root systems.

Do not hold seedlings by their stems, which bruise easily. Gently hold them by the leaves and lower the roots into a hole in the new pot. Firm the soil over the roots and water immediately. Leave at least 2 inches between pots for good air circulation and sufficient light. As plants develop, fertilize weekly with a diluted liquid fertilizer solution relatively high in phosphorus to encourage a strong root system.

As spring approaches, transplants can be acclimated to the outdoors by placing them in a cold frame. Cold frames, or hoop houses, are low-cost, solar-generated greenhouses made by pulling clear plastic covers over wood or plastic frames. A simple cold frame facing south to southeast can be adjusted to regulate the inside temperature by lowering or raising the lid. A blanket can be thrown over the frame on cold nights to protect transplants from chilling.

For more information, please visit New Mexico State University's Cooperative Extension Service (CES) Publications website.