How to Grow Your Own Transplants

How to Grow Your Own Transplants presented by Hank Taber

Hank Taber, Professor Emeritus and Extension Vegetable Specialist at Iowa State University, conducts research in earliness techniques, irrigation practices, and vegetable fertility practices. He has over 40 years of experience in market vegetable production, having grown up on a fruit and vegetable farm in western New York. On Saturday Taber presented on the topic of vegetable transplant production.

There are several reasons a grower would want to produce his or her own transplants. It ensures germination for expensive seed, helps get a crop in the ground earlier, provides uniform stand and harvest, reduces the time a crop is in the field, and eliminates the need for thinning. Some crops, however, are not cost effective or not adapted for transplanting (e.g. sweet corn or some cucurbits).

The three factors of successful transplant production are temperature, water, and nutrition. The soil should be kept at 80°F for uniform germination and then 75°F by day and 65°F at night to grow out the seedlings. Sufficient moisture is essential for healthy transplants, but transplants can be hardened off by withholding water. It is important to test your water for pH, alkalinity, and salt content before using it for transplant production. And water should be at least 68°F when irrigating seedlings. Nutrition is essential for seedling growth and deficiencies can lead to less vigorous growth in the field and lower yields.

Common problems in the greenhouse are high temperature, over-watering, and low light. These factors contribute to transplants that are spindly and soft and have low success in the field. Other problems in the greenhouse include ethylene damage from burning gas, low germination temperature, excess fertility resulting in soluble salts, and poorly drained media.

Hardening off is an essential step of the transplant process. It involves acclimating the seedling to the growing conditions present in the field by disturbing the optimum growing conditions it has experienced in the greenhouse. Hardening off can be accomplished by reducing temperature, increasing ventilation, withholding water, or reducing fertilizer application. Of these options, withholding water is the most practical.

Providing your transplants with a smooth transition into the field is important. Factors encouraging success in the field include using young, vigorous plants, minimizing root breakage, keeping cotyledons intact, and avoiding over-hardening. It is important to transplant under favorable conditions, with cloudy skies and low wind speeds. Immediate watering is essential to minimize transplant shock. Lastly, it is important to use a starter fertilizer solution with a high phosphorus content. Compost can be used for this purpose.
(by Luke Freeman Senior at the University of Missouri, majoring in Sustainable Agriculture.)