Bringing Houseplants Back Inside

If you are like me, your houseplants get moved outside as soon as the weather warms above 50F at night in the spring. There’s nothing like sunlight, and breezes to put some real growth on tropical plants. Nearly all of your houseplants are tropicals’, so the summer heat and better quality and quantity light make a huge difference in their growth. As our nights get cooler and longer, it is time to bring those that will fit back inside. There are a number of things that you can do to make this transition easier and your plants a lot happier.

Begin by getting your house ready. Clean your windows inside and out in order to make the best of what light is available. It’s probably not worth putting plants in windows that face North or are heavily shaded by structures or evergreen trees. You’ve still got time to build or purchase plant stands to make the most of your better lit windows.

Not every plant that went outside will necessarily move back in. Some simply got too big over the summer. Several of my tropical Hibiscus are now over 4’ tall, so will not fit in my windows. You may want to take cuttings of these plants instead of moving them back in (see the note on cuttings at the end of this article). Once you take cuttings, consider donating the mother plant to someone needy of a plant companion.

Before I even start the process bringing in the plants, I treat the pots with one of the pelleted slug controls that contain Iron phosphate: Sluggo, EscarGo, & Slug Magic. There may be more brand names, so look for the active ingredient, “Iron phosphate.” This material is much less toxic than the older metaldehyde baits, is considered safe around pets and is approved for organic growers. You won’t kill any slug eggs that have been laid, but you will greatly reduce any hitchhiking adults. Once the plants have been inside for about 2 weeks, I retreat all of the pots after a thorough watering. It’s important to water first, so the pellets last as long as possible. This will help you get any young slugs that have hatched.

The other treatment that will greatly reduce hitchhiking pests before you bring them inside is a thorough application with insecticidal soap. Spray every surface of the plant to the point of dripping. This will help to kill any Spider mites, Aphids, and Whiteflies that are hoping for a winter home. I can repeat this treatment after 7-10 days inside if necessary due to insect emergence from the soil or eggs hatching. The bathtub is a great place for this treatment once inside.

The big question is: When to bring the plants in? Some plants will start to get damaged at anything below 50F, others will tolerate 45F or even a little lower. Look at your projected night temperatures out 10 days at Weather.com. This handy resource will let you know how soon to get your act in gear.

OK, you’ve killed the slugs and smothered any obvious pests with insecticidal soap, now it’s time to start inspecting the plants that should be moved in. Remove any plant debris from the soil surface plus any yellowing or discolored leaves, dead flowers and damaged or sick looking stems. If the top of the plant looks clean, you can move on to the roots and soil. Pull the plant from the pot. Look for roots that are clean, white to light green and soil that does not appear riddled with insect tunnels. Some specialists recommend soaking the root ball in lukewarm water for 15 minutes to force any soil pests out.

If you are clear of pests and the roots don’t appear to be root-bound, then this plant is ready to move inside.

If the roots are heavily encircling the root ball, then a late season repotting may be necessary for good overwintering. Use a pot one size larger (6” pots get moved into 8”, 10” into 12” or 14” and so on) and the best potting soil you can find. For this purpose, I prefer soil media that have 25% or more coir or composted bark. If the plant has gotten leggy over the summer, then cut it back.

The lower light levels of a home in the winter requires a lighter hand in fertilizing than you should have been applying over the summer. This is the ideal time to use slow release fertilizer pellets such as Osmocote. If you follow the label directions, a single dose will almost get you to March. They are usually rated to last so long (typically 4-5 months) at 70F.

There’s a fine line between enough water to keep a plant alive in the winter and under or over watering. In order to avoid root diseases, let the soil surface get very dry before thoroughly watering again. Cloudier days will slow the need for watering.

Notes:

1) Shade loving plants like Begonias overwinter well under a bank of regular daylight fluorescent lights. We simply raise our transplant starting lights up to the top of their canopy and set the timer for 10 hours of light per day.

2) Heavy insect infestations may require either tossing the plant or the use of a systemic insecticide that contains Imidacloprid. Don’t take the chance of infesting your healthy plants for a questionable one.

3) You’ll readily find lots of detailed instructions for rooting cuttings online. In general, stick clean, non-blooming stems in moist potting media, mist them regularly for 1-2 weeks and pot them into small pots after about 4 weeks. Rooting hormones which are available from many garden supply sources will speed this process.

4) You can bring potted annuals like peppers in as well. For potted peppers, place them in your brightest window until all the fruit is harvested. Once done, remove all unripe fruit, prune back to about ½ the size and keep somewhat dry until ready to revive it in the spring for really early peppers.