Last fall, as the evening temperatures dipped below 50F, I brought my houseplants inside off of my deck and porch. They have sat in a south-facing window for about six months now. Low humidity, less light than needed, and sporadic watering have taken their toll. They need to go back outside soon.
So when can they be safely moved out of the house? The 50F temperature that dictated the move inside in the fall works for bringing them out this spring. When the evening temperatures stay above 50F, the plants can safely go out. That is typically the month of May in Buncombe County.
There is a caveat. The plants can experience shock and even death if not first being acclimated to their new location. This acclimation, also called hardening off, allows plants to adjust to changes in temperature, light and wind. I open the windows a few weeks before the plants go out, making the temperature adjustment easier.
Both temperature and light need to be gradually adjusted. Even if your houseplants wintered in a sunny window, light intensity is greater outside. First place the plants under a tree or on a shaded porch so the change will not be too great. Then move to a brighter location for a few hours a day. Then they can be moved to a sunny location. Just make sure that the plant needs bright sunlight. If they are shade lovers and placed in bright sunlight, no amount of adjustment will keep that plant from being burned. Shade lovers should remain in the shade.
Rootbound plants can be repotted at this time. Remove the plant from the pot, and if the roots are circling around the root ball, repotting is indicated. Select a new pot that is slightly larger and use fresh potting mix. This change will encourage root growth. Water the new transplants thoroughly.
When watering, always completely soak your plant, as the roots are normally in the bottom two-thirds of the pot. Check to see if watering is needed by putting a finger about ½ inch into the soil. If the soil is dry, water. Pots become lighter as the soil dries, so lifting the pot when newly watered will feel heavier than a dry pot.
Since the plants will now be actively growing, fertilizer is needed. Many houseplant fertilizers have a formulation of 20-20-20. Fertilizing in spring and summer is needed about once a month, but first read the fertilizer label. Too much fertilizer can cause a decrease in growth, burned or dried leaf margins, browned roots, loss of lower leaves, and even death of the plant.
Warmer weather is coming, and both you and your houseplants can enjoy the summer outdoors.