FARGO, N.D. — This week I will haul my seedlings home for the second leg of their school garden journey. They are going to spend a few weeks in my yard adjusting to the outdoor environment before they are finally planted in the gardens. While this step is a lot of work, I would really regret if I didn’t take the time to help my transplants adjust to the conditions outdoors.
The horticulture term for adapting plants to the outdoor conditions is hardening or hardening off.
Before plants grown indoors are planted in the garden or moved outside for the summer, they do need time to get used to the outdoor environment. Let’s face it, the indoor environment is cozy for plants. Temperatures don’t change that much and there is no wind. Whereas outdoors there is intense sunlight, temperature extremes and almost always 40 mph wind!
Plants that are quickly moved outdoors into full sunlight and wind exposure can experience setbacks in growth or even die.
To prevent gardening setbacks, gradually introduce your seedling or plants to the outdoors. Even seedlings or plants purchased from greenhouses can benefit from getting used to the outdoor environment.
To start, put plants or seedlings in a shady spot out of the wind for a few hours a day and bring them in at night. Gradually extend the amount of time plants and seedling are left outside, increasing their exposure to direct sunlight and wind.
Eventually, you will be able to leave them outside overnight. However, it is best to keep an eye on the nighttime temperatures. It is still early in the season, and our weather can be unpredictable. If freezing temperatures are predicted, move your plants indoors, especially heat-loving plants like tomatoes and peppers.
It is a good idea to protect your valuable seedlings and plants from garden critters that would enjoy a fresh snack. Put up a fence around them or place them off the ground to help deter pests from snacking.
Keep in mind other outdoor work that others may be doing this time of year. Many will be out taking care of their lawns. Prevent any unintentional damage by keeping your plants and transplants that are hardening off away from property lines and fences.
When it finally comes time to put your seedlings or plants in your garden, if possible, plant on a day that is cooler and not too windy.
Remember to water the plants right after planting and continue to monitor the soil moisture levels over the next several days as the plants settle into their new environment. Happy gardening!
— Carrie Knutson, NDSU Extension
