Hardening Off Greenhouse-Grown Plants
In our midwest climate, cool spring temperatures, strong winds and bright sun can be very stressful to plants that have been grown in a greenhouse. To minimize risks to tender plants, they must go through a process known as "hardening off."
|Steps to Hardening Off Plants|
|Set the plant outdoors in a sheltered area for a couple of hours on nice mild day and return indoors at night.|
|Indoors could be the garage or a garden shed if it’s a mild night.|
|It's important to protect the plants from strong sun, wind, cool temperatures and heavy rains.|
|Each day, the plants can be exposed to one more hour of direct light.|
|Each night, move the plants back to a sheltered and enclosed environment.|
|The process can take 7 to 14 days, depending on weather conditions and the variety of plant.|
|During the hardening off process, carefully watch the weather forecast, especially the first few days. If strong storms or low temperatures are forecast, keep the plants inside.|
|Plants that are perennial but forced in a greenhouse will handle temperatures down to 33 degrees but will benefit from a plant cover like a cardboard box or an old nursery pot.|
|After the hardening off process is completed, your plants will be able to tolerate most of spring's unpredictable weather, but continue to take steps to lessen their exposure to extreme conditions.|
Plants that are hardened off are sturdier and put on new growth much more quickly than plants that are not hardened off. If you plant a hardened off plant next to a plant that wasn't, it will take the plant that was not hardened off about one month to catch up. Hardening off, it is a little extra effort, but definitely worth it.