Time to prepare houseplants for winter

If you haven’t already moved houseplants back indoor, now is the time to begin planning the transition. Nighttime temperatures that consistently begin to stay under 60 degrees are the signal we look for.  These temperatures feel good to us, but for houseplants it could be deadly.  Most houseplants are from the tropic and will be damaged by cold temperatures. Here are some tips for transitioning houseplants back indoors for winter.

Prepare plants for the transition

First, inspect the plants for pests, taking a close look at both upper and lower leaf surfaces. If you find insects, remove them by hand or try washing/cleaning them away. If that doesn’t work, apply a houseplant insect control before bringing the plant inside. Wash the pot’s sides and bottom, and check the drainage hole.  Often, there is a large cavity filled with roly-poly’s (pillbugs). 

Second, repot if necessary.  In some cases plants may become root bound in their pots over the summer and be in need of repotting.  While spring or summer repotting is preferred, fall repotting will be beneficial if plants are extremely root bound.  Pick a new pot that is no more than 1-2 inches larger than the old one. 

Third, place the pot in the brightest indoor light you have – but not direct sunlight. The tropicals we grow typically come from the underside of the jungle canopy. They burn up in direct sunlight. But they also can have trouble adjusting to indoor lighting again – which is never as bright as where the plants have spent the summer.

Expect changes

When a change of light level is abrupt, plants often drop their leaves and try to replace them with leaves that are more suitable to the new light level. So long as the stems don’t get dry and brittle, be patient, and keep up the care.

Some tropical plants can actually produce two kinds of leaves, depending on their light conditions.  They may drop most of their “sun leaves” when light availability plummets, and replace them with “shade leaves”.  “Sun leaves” tend to be thick, small and numerous. They have less chlorophyll and it’s buried deeper in the leaves. (Chlorophyll makes plants green and allows plants to convert sunlight to energy.) These leaves have lots to work with so don’t need to efficiently use every available ray.  “Shade leaves” are thinner, larger and fewer in number. They also have more chlorophyll that’s closer to the surface. Their dim conditions mean they must convert more of the light that’s available.

To make a plant’s adjustment less stressful, start it out in the brightest indirect light indoors. Then, over the next four to eight weeks, move it into less light and finally its winter home.

Winter care

Water and feed at regular levels once when moving indoors. Then put the plant on its winter “diet.” Water only when the top inch of the soil is dry.  It is very easy to kill a houseplant by overwatering during the winter. Rather than evaporating, any excess moisture now will tend to fill up the soil spaces normally occupied by air, thus suffocating the plant.  Fertilization is generally not necessary during the winter months because most plants are growing very little or resting. Gardeners can begin to fertilize houseplants in March or April as growing conditions improve and the plants resume growth.

Remember: Even when plants are indoors, they still react to winter’s shorter days. They won’t need as much water or food until they start their next real flush of growth sometime in spring.