Every year at this time our office seems to turn into a greenhouse as we fill our windows with those plants we just couldn't let go. The giant ruffled red coleus, the tender snail vine raised from seed that will hopefully bloom next year, a still-blooming lantana, a large Kimberly Queen fern, a few water hyacinths and our annual winter resident tropical hibiscus and Egyptian papyrus have all made the cut (so far). It's just too sad to watch our little green babies suffer and deteriorate as the nights get increasingly colder, until finally succumbing to Jack Frost. So in they come. And why not? If you have the space and the right conditions indoors, there's no sense in tossing out a perfectly healthy plant at the end of the season.  

If this is not done, many plants will partially or completely defoliate in an attempt to rescue themselves - more sudden and extreme changes will result in greater degrees of leaf drop. Leaves grown under high light will not function properly in a low light environment, and vice versa. Therefore, the plant has no choice but to shed those leaves and try to produce new leaves that match their current conditions. The leaves of plants grown in sun are usually smaller, thicker, and darker green than those of the same plant grown in shadier situations.

You actually want that to happen if you intend to store plants in a cool (temperatures stay above freezing to about 50 degrees) basement or garage - you need them to enter dormancy before moving them. Then you'll simply water them before you put them in storage, and perhaps once a month after that depending on the size of the container and the temperature.  You don't want the roots so wet that they rot, but neither do you want the plant to dry up completely. Definitely do not leave them in water-filled saucers!

For tubers, corms, and bulbs wait until the first frost damages the foliage, then dig and cut back. Give them a few good shakes to knock off most of the soil and lay them in a cool, shady spot to "cure" for a few days to a week - basically drying them out a bit.  You can do this outside if no rain is expected and you don't have critter issues. Once the bulbs have cured, place them in a paper bag, box, plastic bin (or whatever you have handy) and store in a cool, dark spot. Adding peat moss, etc. is really not necessary. Check them every few weeks or so to be sure they're not drying out too much - mist lightly if they start to look slightly shriveled. You can replant outside after frost, or start them up early inside so they're ready to go out at the proper time in spring.  

To transition plants like bananas, hibiscus, angel's trumpet and other woody tropicals, cut back on watering and place them in the shade during the 2 weeks before you intend to bring them in to encourage them to enter dormancy. Cut back bananas to about 6 inches, but woodies can be left alone (if you have room) and pruned in spring once you're able to distinguish between live and any dead wood.  If you've brought a plant inside the house and conditions are making it just too ugly, you can always revert to dormant storage to give it one last chance instead of tossing it!

It's pretty easy to acclimate non-dormant outdoor plants before you move them inside. Simply place them in a progressively shadier condition over the course of at least a week - ideally two weeks. The longer you give them, the better they'll fare in the long run. Even if you're bringing the plant into a sunroom or atrium, they will benefit from this treatment, since the sunlight will be lessened somewhat as it passes through the glass. Be sure to get this accomplished before temperatures drop too low - most tropical plants will suffer some damage below 50 degrees F. If plants are in the ground, digging and potting at least a month before they go in can help with their adjustment (no matter how you're going to store them).

And remember to follow this same process in reverse when plants go outside again next year. Slowly start watering again, and move them to progressively sunnier spots over the course of a couple of weeks to avoid sunburning the foliage. Give them a light dose of fertilizer once you see new growth, and resume your regular outdoor care regime once they're fully lleafed out and re-acclimated.

All that being said, do we always do that? Uh, not gonna lie, no we don't. Do the plants still live? For the most part the answer is yes. It depends on the type of plant and the degree of lighting and temperature change.  Evergreen woody plants (citrus, brugmansia, hibiscus, ficus) will definitely have the most difficulty adjusting, and some degree of leaf drop is to be expected. However, as long as they are not over or underwatered and are receiving proper lighting during this time all is not lost -  they should begin to sprout new leaves eventually. The worst thing you can do during this process is overwatering  - rotted roots cannot be overcome.

It's Not the Heat, It's the Humidity

If you're overwintering anything tropical, as long as your indoor temperature is above 55 to 60 degrees they should be fine, although they'd probably enjoy something closer to 70, just like you. However, it's very unlikely that your home with naturally provide them with their preferred level of humidity. An average home in winter might have a relative humidity of 35 to 40%, while many plants will benefit from 60 to 70%. Grouping plants can help increase the humidity around them, as can placing them on pebbles in a saucer of water, and topping that up as it evaporates. Be sure not to site plants near heating vents or drafty windows or doors. While light, water, and minimum temperature are critical, insufficient humidity won't kill your plants, especially if they're only inside for a few months. But you may see some browned tips or edges, possibly an increase in insect populations, and it could be the tipping point if other requirements are not met. 

Don't Bug Me

I's very important to thoroughly wash your plants before you bring them in - a strong spray of water from the hose will remove most pests. Look closely at new growth and the undersides of leaves in particular. Insect populations can increase rapidly indoors and there are no predators for natural control, so you definitely don't want to bring in univited guests with your leafy visitors. This is especially important if you are placing the plants in a room with existing house plants. If you do find insects, you can treat with a granular systemic houseplant insecticide that is sprinkled onto the soil and watered in. Or, if you prefer the strict organic route, a summer weight horticultural oil or neem oil will do the trick. No matter what you choose, read the label instructions to be sure your remedy is safe and appropriate for both for insect and plant alike. For instance, neem oil should not be used on plants with hairy leaves (like African violets), and insecticidal soaps can damage palms, ivies, and ferns. Also important is to mix the solution properly if not using a ready-to use formula - plants may not tolerate a heavier mixture than recommended.

Really check well for insects like scale whose mature forms don't move and resemble brown bumps on stems and the undersides of leaves. These can suck the life out of susceptible plants like bay leaf and citrus trees. Sometimes the first sign will be a shiny, sticky substance on the upper surface of the leaves - this "honeydew" is the excretion of the scale insect. If you look above that leaf you're likely to find the culprit on the underside of an overhanging leaf or stem. Remove all that you find with a q-tip soaked in rubbing alchohol, and keep a weekly watch thereafter. In future, familiarize yourself with the lifecycle of the particular scale insect so that you can apply the proper pesticide when the new generation (crawlers) is active and before they form their protective "shell."

Be alert for anything below the plant's canopy on the floor, furnishings, etc. You might notice the sticky honeydew there and just figure someone spilled a drink!  A sprinkling of "dirt" beneath the leaves should also put you on alert.  Dirt doesn't usually fall from the leaves, and if you look carefully you'll see that the specks are spherical - a sure sign of caterpillar feeding.  What goes in must come out, you know.  If you've caught it early you may find one or two small holes in the leaves that also announce its presence.  A hard shake of the branches can sometimes dislodge the pest - otherwise you'll need to look the plant over extremely thoroughly to find your little friend. I like to put them on the birdfeeder - a tasty treat for visiting wrens. 

What plants do well with indoor-outdoor transitioning? Theoretically, anything that is perennial somewhere could be overwintered inside. In general, the less humidity a plant requires, the easier it will be to winter indoors, so you might want to research that before you buy if that aspect is important to you. We're focusing here on plants that do well in mixed containers, or plants that would typically be used only as annuals for seasonal color.

Blooming Plants:

• Geraniums:  Both zonal geraniums and their scented geranium cousins will do well in a sunny window, and may bloom for you as well.

• Lantana: Place in a sunny window indoors over winter where not hardy outside.

• New Guinea impatiens: Watch for aphids and give them some sun inside over winter. 

• Begonias: wax (bedding) types, Rex, and cane types like angelwings and dragonwings
• Cuphea:  'Mexican' heather (C. hyssopifolia) is the most familiar variety, with small but numerous light purple flowers and small glossy leaves.  Stunning red-flowering varieties are also available, from the old-fashioned bushy upright 'cigar plant' (C. ignea) to the semi-upright trailing 'batface' cuphea (C. llavea).  Newer varieties are more compact and mounding, but all are hummingbird magnets, including other species with yellow, orange, or pink flowers.

• Streptocarpella: A blue-flowering cascading relative of the African violet that thrives in shade outside and bright light inside - will bloom all winter!
• Pentas, or Egyptian star flower:  Round clusters of blooms in red, pink, yellow, lavender, or white on a bushy plant that will thrive in a sunny window. 
• Hibiscus: It's definitely worth wintering these shrubs over indoors, especially if you have a favorite color that is difficult to find.
• Ixora (jungle geranium): Essentially an evergreen hedge plant in Southern Florida, but you can grow it as a beautiful blooming pot plant.
• Crossandra: soft peach, bright orange, yellow, red, or pink flowers and a loosely mounded or bushy upright habit, depending on cultivar. Fairly slow-growing, so overwintering will give you a jump on a larger plant for next spring.
• Citrus: need to be kept cool and bright, and on the dry side for winter.
• Ornamental peppers: Those with green, black, purple, or purple variegated leaves and variously colored fruits are readily available in the fall, and can continue to bloom and produce fruit through the winter in a sunny window.

Foliage Plants:

• Tradescantia varieties: Most familiar is a trailing plant with purple fleshy leaves and stems and pink summer flowers, but there are also newer types with bright pink striped foliage and smaller leaves.
• Syngonium: This plant is seeing a resurgence with houseplant collectors, thanks to the plethora of pink hued, veined, blotched, spotted, and speckled varieties.  It's always been a great plant for mixed containers, yet was never widely available. The attractive arrow-shaped leaves account for the common name of arrowhead plant. Plants start out bushy, becoming trailing as they grow.  You can bury part of the stem in the soil as it grows longer - this will create a bushy plant in the pot if you prefer, or you can separate the rooted sections as you please. You'll easily find foliage with varying degrees of white or pink variegation, and soon more with yellow variegation will likely arrive in the marketplace. Bright light and evenly moist soil suits them best, but as with most plants, keep them a bit drier in winter. This easy plant should definitely be on your "to grow" list.

• Spider plant: Boring as a houseplant, perhaps, but really nice in a shade container garden, adding texture and variegated foliage. If you have cats, they will eat these down to nubs, which is ok for them as ASPCA rates these as non-toxic. Not so good for the plant, though. Curly varieites (Bonnie) are interesting, and there's more than one type of linear variegation, although you might not notice unless you compared them!

• Snake plants: Varieties seem endless now - large flat leaves, tall narrow leaves, cylindrical leaves, compact, tall and a plethora of variegations. They do suprisingly well in mixed shade containers with almost anything - even ferns and impatiens. Since they grow fairly slowly and are the easiest of all houseplants, there's no reason to let them turn to mush with the frost.  For easy overwintering, plant them in the container in their own pot, then just pull the plant out in fall and trim the roots.

• Piggy-back plant: A old-time favorite for shade hanging baskets and medium to bright light inside - and has low humidity needs to boot. 

• Coleus: They grow to such impressive sizes that it's really hard to kiss them goodbye and turn your back! With so many varied leaf shapes, colors, and habits, you could have a whole house full with no two plants alike. Keep these in bright light inside, even though they may do fine in shade outside. They also prefer to be kept a bit on the dry side. If you don't have room to overwinter the whole plant, take some cuttings in late summer and plant them in a smaller pot.  

• Swedish ivy:  Trailing Plectranthus varieties frequently masquerade by this name, but there are also bushy, upright species with habits similar to coleus. These have thick, fuzzy leaves that may be green, gold, grey, or purple or variegations thereof - some also have showy spikes of pink, purple, or white flowers. The shade-tolerant golden swedish ivy has always been my favorite - bright gold textured leaves with a deep green center and a compact, trailing habit - looks gorgeous with everything! White flower spikes occur mostly in fall and spring, but sporadically all year is possible.

• Blood leaf (Iresine): Deep pink or pink, green, and white variegated rounded leaves; most common variety has an upright growth habit. 

• Joseph's coat (Alternanthera):  More colors, habits, and leaf types than you can shake a stick at, and they're all fabulous. Some are large and trailing, some are neat and bushy, but color is key, with foliage in bronze, purple, red, yellow, pink, white, green - solid or combinations.  Maybe just as much fun as coleus for building a color combo around!

• Hawaiian ti (Cordyline): These colorful upright tropical plants are usually a bit pricey, so they're worth saving if you have room. These usually prefer cool and bright conditions similar to citrus inside.
• Coprosma: If you like crotons but would like a more adaptable plant with orangey foliage and don't want coleus, try Waxwing Orange coprosma, also called mirror bush. Coprosmas are generally compact, small-leaved, and bushy, with varying foliage colors, and are more amenable to indoor conditions than are crotons. They'll be gorgeous in your outdoor summer pots and should perform well inside over winter.
• Cyperus spp:  Usually called papyrus, these elegant tall-stemmed plants are topped with foliage resembling exploding fireworks.  Some can grow to immense heights, like the potentially 10' foot high 'King Tut,' but they can be restrained somewhat by the size of their container. I keep mine in my small above-ground water garden in the summer, and winter it indoors in a pot without a drainage hole so it doesn't dry out. Takes the worry out of watering!
• Boston, Kimberly Queen, Macho ferns and the like: These can take on gargantuan proportions over the summer, but if you have room and a sunny window they are easy to winter inside.  Or just chop off and pot up a smaller, more manageable chunk - you will need a very sharp spade or knife.  Expect some yellowing leaves and some leaf drop (of course, they shed virtually non-stop, anwyay), but they usually look pretty good with enough light.
• Phormium:  These pricey, somewhat slow-growing colorful thrillers would be at the top of my list to overwinter.  They'll do best in drier, cooler conditions and bright light for the winter.

Tubers, Corms, and Bulbs to store dormant:

• Dahlias

• Cannas
• Alocasia/Colocasia (Elephant ear)
• Tuberous begonias (Non-Stop)
• Gingers
• Calla Lilies
• Pineapple Lily (Eucomis)
• Caladium
• Gladiolus

Please Note: Our plant recommendations are only suggestions, and may not be appropriate for your particular area. Always consult your local cooperative extension service, master gardener's program, state natural resources department, or trusted independent nursery for information on what plants may be invasive or best grown in your location. Thank you!