When temperatures reach the lower 50’s, many tropical plants will suffer. If you haven’t brought your plant babies in by the time the night time temps hit 50, do so right away, as a good portion of them will be stressed if not damaged. Knowing the requirements of each plant is helpful, so you don’t have to move them all in one day. (I imagine you have as many as I do, and the real chore is finding a place for them all inside!) I know my Ivy, Myrtle, or Agapanthus are fine until is gets into the upper 30’s, but the Coleus, Ficus, and Croton don’t like anything below 55. Though they might be fine for a bit longer with microclimates around the house. Thank goodness, because I never get to this job in time!
Ideally, on a warm sunny day, hose them down to get dust and insects off, and then if you feel you need to, you can spray the leaves top and bottom, stems, & soil surface with a natural insecticide like neem oil. Sometimes I’ll gently slide the plant out of the pot to see if any insects are living there. If the pot was directly on the ground, pill bugs or other insects can crawl in. I don’t worry about just a couple of them though–if a few are in there, they aren’t leaving the soil to explore my house! Ants are an exception–if I see them, I make sure they stay outside by hosing the roots down and adding new soil.
After all that summer growth, you may need a slightly bigger pot. Or just a new look for in the house. Choose a pot only an inch or two larger and add a good potting soil, nothing from the yard. For larger plants that can’t go into larger pots, you may want to add a thin layer to the surface of the existing soil. This is a good idea if the soil level has dropped a bit, as happens over time. Don’t bury any trunk or stem with soil though as this will eventually kill your plant by rotting the bark. You can also remove the plant from the pot and add more soil to the bottom before replacing.
Try to place plants in a similar lighting area that they had outside. If your house is like mine, with limited sunny spots, supplement with grow lights. There are many styles to choose from, so you can set up a whole shelving system or just have a full spectrum bulb in a single lamp for one plant.
Generally, this is not the time of year to fertilize, as most plants will be going into a slower growth phase with less sunlight available. Watering also will probably need to be adjusted down for the winter. As always, you are welcome to stop in for advice for your specific plant!