Issue: December 22, 2007

Starting transplants indoors in winter

I want to start my vegetable garden from seed during the winter. When I tried this in the past, the plants were very skinny and many of them fell over and died before I could transplant them outside. What did I do wrong?


There are several things that may have gone wrong. The tall and skinny characteristic suggests too little light in the location where you grew your plants. Even if they receive direct sunlight, they may not have enough light unless they receive direct sunlight for at least 4 hours each day. Long hours of diffuse light may be better. Provide this by putting sheer curtains in the window in which the plants are growing. These curtains will reduce the peak light intensity allowing the plants to develop leaves that photosynthesize more efficiently. The curtains also diffuse light into the room providing more light when the sun doesn't shine past the curtains. Thus, the plants produce food photosynthetically for a greater part of the day than if they were in the sunlight for only a couple of hours.

Another factor causing "legginess" in your plants could be your attempt to help your plants by fertilizing. Plants need nutrients, especially nitrogen, but an excess of this nutrient will stimulate too much growth if there is not sufficient light. Less fertilizer may actually help.

Another consideration is the temperature of your home. Many people keep their homes warmer than the vegetable transplants prefer. The sunny location in which you grow your plants will be warmer than the rest of the house. If the house is already warm for your comfort, the plants may be too hot. Higher temperatures cause the plants to respire more, burning the food created by photosynthesis too rapidly. Cooler temperatures in the room in which you grow your plants may help.

Finally, the description of the plants falling over suggests that there may be a disease involved. Seedlings and young transplants are very susceptible to “damping off” disease that causes the stem of the plant to collapse at the ground level. The plant then falls over and dies. Too much fertilizer, too much moisture, and too little light favor the growth of the fungus that causes this disease. Many gardeners pasteurize their potting soil, or purchase "sterile" potting soil to avoid this problem. This is a good idea, but improving other aspects of your indoor gardening environment will also help.

Starting your own transplants indoors is enjoyable, but can also be a challenge. Best wishes for an enjoyable, early start to your vegetable garden.

For more gardening information, visit the NMSU Extension publications World Wide Web site at

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!