How to Harden off Seedlings – Harden the seedlings to harden them for transplanting outdoors. When you harden vegetable and flower seedlings that began life inside (thanks to you or a commercial producer), you help the young plants acclimate gradually to the bright light and cooler temperatures of the outside world. This process slows down plant growth, causing the plants to store more food inside and to increase the thickness of layers of their outer leaves.
How to Harden off Seedlings
To harden your transplants, watch these steps:
- A week or couple before you plan to plant in your garden, stop fertilizing and reduce the amount of water you give them. Give plants just enough water so they do not fade.
- Take your plants outside for a short period. Give the plants a half hour of filtered sunlight (light gray) – placing them under an arbor or in the tree branched – during the hottest part of the day. If the weather is long-winded, put the plants in a place where they are safe, or build a windbreak on pieces of wood.
- Gradually increase the amount of time that plants go outside and intensity of the light they are exposed. Want to improve the amount of time your plants are outdoors so that by seven days, they are outside all day. Move them in sunny locations gradually during the week, so they use their future condition in the soil. However, make sure that you carry the plants in every night.
Another option is to move your plant to a cold frame, and then you can open the cold frame more each day and close at nighttime. Plants that are raised in a cold frame from the time they are young plants need much less hardening off.
Tips: Do not overharden your plants. Some crops, such as cabbage and broccoli, can quickly bolt old plants over three weeks are repeatedly exposed to temperatures below 40 degrees for a couple of weeks.