Moving Your Plants Outdoors
Linda Moll, Anoka County Extension Master Gardener
Even when it's to a bigger and better location, moving is stressful – for us and for our plants. Whether you start seeds indoors, purchase annuals and vegetables from a garden center, or have houseplants that like to spend time outside, you can help them transition successfully to their new environment.
Hardening off is the process of helping plants make the move from indoor living to outdoor conditions with a minimum of stress. Our backyards and decks are going to be brighter, windier, and cooler (especially at night) than our indoor plants are accustomed to, so we want to gradually introduce them to those conditions.
Cold-tolerant plants like pansies and kale generally don't need to be hardened off. Neither do plants that are already outside at your local garden center. However, while greenhouse plants might be used to light, they won’t be accustomed to the cold and wind. If you aren’t sure about the specific needs of a plant, ask the staff.
Working with seedlings
If you’ve started flowers and vegetables from seed, hardening off is an important step to ensuring they survive transplanting. Here are some tips for success:
While the seedlings are still inside, you can start the acclimation process by using a fan to mimic a gentle breeze. Place the fan across the room and on a low setting, running it several hours a day.
When temperatures are consistently in the 50s (or 60s for some tender annuals), and at least two weeks prior to your scheduled transplant date, start bringing plants outdoors for a few hours per day.
Select a shady area where plants will be protected from the wind. Set them in an open cardboard box for extra shelter, if needed. Bring them indoors at night.
Gradually add outdoor time each day, and slowly increase sun exposure. After two weeks, the plants should be able to remain outside provided temperatures stay well above freezing.
Acclimating Houseplants
Follow the same techniques as for seedlings but remember that most houseplants are tropical and cannot live outside if temperatures drop below 50 degrees.
Many houseplants only tolerate indirect light or require full shade, so know your plant’s needs before moving them outdoors.
Check moisture levels often, as plants exposed to wind and sun need more water than those living indoors.
Greenhouse Plants
Those new tomatoes or petunias from the nursery are going to end up in your garden or patio pot. Help prevent transplant shock, which causes wilting plants and curling and/or dropping leaves, with a few simple steps:
Harden off plants, if possible.
Plant on a cloudy day.
Water the soil at the transplant site prior to planting.
Disturb the roots as little as possible.
Avoid fertilizing until roots have gotten established in their new home.
A successful growing season is all about preparation and timing, and that includes helping your plants adjust as you move them outdoors. For more tips about hardening off and transplanting, visit: https://extension.umn.edu/planting-and-growing-guides/starting-seeds-indoors#hardening-off-seedlings-117986