As summer winds down, we tend to focus on enjoying the last of the season's harvests, clearing away spent plants and planning next year's garden. But indoor plants need our attention now, too.
PLANTS THAT ARE COMING INDOORS
Houseplants that spent the season vacationing outdoors need a proper transition back into the home to avoid shock.
If they have outgrown their containers during their holiday, this is a good time to replant them into a larger pot. Select a container no more than 2 inches wider than the current pot and replant in fresh potting mix, then water well.
Overgrown plants can often be divided into two or more. Spider plants (Chlorophytum), peace lilies (Spathiphyllum), flamingo flowers (Anthurium) and peacock plants (Calathea) are among those with clumping root systems that lend themselves to division.
If you find removing the plant from its pot difficult, check whether roots have emerged from the container's drainage holes. If so, pull or cut off any escaped root fibers to set the plant free.
Then, to divide the plant, carefully shake off as much soil as possible. Find the junction where the plant's top growth meets its root system, and either gently pull the roots apart or slice through them with a sharp knife, ensuring that at least three healthy leaves are attached above each root portion. Repot each new plant in its own container using fresh potting mix. Keep the plant well-watered (but never soggy) until new growth appears.
Whether or not repotting or dividing is necessary, all outdoor houseplants should be moved into a shaded spot for a week or so to gradually acclimate them to lower light levels before their move indoors. Continue to water during this transition.
At the end of the week, inspect all plant parts for insects — including under leaves — and thoroughly rinse leaves and stems with water to avoid transporting hitchhiking pests into your home. To play it safe, you might spray the plant with a diluted Neem oil solution.
Complete the move before nighttime temperatures drop below 55 degrees outdoors.
PLANTS THAT HAVE STAYED INDOORS
Houseplants that haven't left their window perches all summer also will need special care as day lengths shorten and diminished sunlight slows their growth.
Although not technically dormant, most houseplants rest during fall and winter, which means they'll need less water and often no fertilizer until spring. Overwatering during this time will risk root rot and the proliferation of fungus gnats, which breed in soggy soil.
For most plants, it's best to wait until the top inch or two of soil is dry before watering. You can check for moisture by plunging your finger knuckle-deep into the pot.
Slower growth also means slower healing, so postpone pruning until spring. You can, however, trim away dead or dying leaves or leaf tips over winter.
Most houseplants are native to the tropics and, as such, require more humidity than is typically found in most homes, especially in colder areas where heating systems tend to dry the air. Run a humidifier in the room or place plants on a pebble-filled tray of water, which will create a humid microclimate around them as the water evaporates.
Never place plants on working radiators, and keep them away from cold drafts and heating vents.
Next spring, when temperatures are reliably higher than 60 degrees, it will be safe to move most plants outdoors. Tender tropicals like African violets, however, are homebodies, so leave them be.
Jessica Damiano writes regular gardening columns for The Associated Press. Her Gardening Calendar was named a winner in the 2021 Garden Communicators International Media Awards. Her Weekly Dirt Newsletter won a Society of Professional Journalists PCLI 2021 Media Award. Sign up here for weekly gardening tips and advice.