Hardening Transplants
The term “hardening” refers to any treatment that results in a firming or hardening of plant tissue. According to Don Janssen, University of Nebraska - Lincoln Extension Educator, such a treatment reduces the growth rate, thickens the cuticle and waxy layers, reduces the percentage of freezable water in the plant and often results in a pink color in stems, leaf veins and petioles. Such plants often have smaller and darker green leaves than non-hardened plants. Hardness results in increased carbohydrates in the plant permitting more rapid root development than occurs in non-hardened plants.
Any of the following can be used to harden transplants. A combination of all these techniques at one time is more effective.
- Gradually reduce water- water lightly at less frequent intervals but do not allow the plants to wilt severely.
- Expose plants to lower temperature than is reported as optimal for their growth. If biennials are exposed to cold for an extended period, they may bolt instead of developing properly. It should be noted that placing the plants outside during the day to encourage hardening and then bringing the plants back into the warm house during the night often reverses the hardening process. Plants could be placed in a cold frame or other area that does not freeze during the night hours without interruption of hardening process.
- Do not fertilize, particularly with nitrogen immediately before or during the hardening process. However, a starter solution or liquid fertilizer could be applied to the hardened transplants one or two days prior to transplanting into the garden or a time of transplanting.
- Gradually expose the plants to more sunlight. This results in the development of a thicker cuticle layer thereby reducing water loss.
|
