As I explained earlier this month, on Thursdays in September I'm bringing you tips and advice for . . .
Suddenly (like . . . yesterday), the temperatures dropped quite a lot here in my corner of the world. We're not close to freezing or anything (yet), but there is definitely a fall-like nip to the air. Now is the time I start thinking about cleaning up my containers and pots. Sure, I'll replace some of them with mums and other fall-hardy plants. But . . . what do I do with the rest of them? Should I try to save non-hardy plants I've grown to love over the summer? Or should I let them go to the compost bin . . . to be replaced next spring?
Yes. Today, we're talking about bringing your outdoor plants . . . indoors (otherwise known as "overwintering")!
So, when is it time to bring outside plants inside?
Most of the plants we grow in containers are annuals (or tender perennials in Southern regions) and cannot survive cold winter temperatures. We can bring many of these plants inside, though, to let them go dormant until next spring -- or even (in some cases) to continue growing through the winter. Alternatively, we can collect seeds from our favorite annuals and save them until spring. Or we can take cuttings and try to propagate plants.
And now? Now is pretty much the time to start in on any of these options!
Ideally, annuals should come indoors before nighttime temperatures dip below 45°F (7°C). As fall weather approaches and night temperatures reach about 50°F (10°C), it's time to start bringing the plants inside for the winter. Most tropical plants will suffer damage at temperatures below 40°F (4°C), a few even below 50°. You will need to act well in advance of any actual frost or freeze to acclimate them.
Which plants should I bring inside?
Unless you have a greenhouse (I dream of having a little backyard greenhouse . . . ), you'll likely have limited space inside for overwintering plants. If you're like me, you'll have to make some decisions about which plants you want to try to save. Think about which plants are your favorites - or which ones have sentimental value. Which of your plants are pricey enough that you'd hate to shell out the money for them again next year? How much space do you have inside -- and what kind of light can you offer the plants during the winter? You should also only bring healthy, thriving plants that are free from pests inside.
Here are lists of good candidates for bringing inside over the winter (either as plants, seeds, bulbs, or cuttings). At the end of this post, you can find some "how-to"resource links with specific information.
- Collect seeds from . . .morning glory and moon vine (Ipomoea), Nicotiana, Gomphrena, Celosia, amaranth, sunflowers (Helianthus), zinnia, cosmos, cleome, calendula, marigold, Verbena bonariensis, annual forms of poppy and larkspur, and certain Salvia, including Lady in Red and Victoria.
- Propagate cuttings from . . . coleus, sweet potato vine (Ipomoea batatas), Impatiens, Alternanthera, Tradescantia, either rhizomatous or cane or wax begonias, and ornamental sages, including Salvia leucantha.
- Store as dormant bulbs or tubers . . . Cannas, dahlias, gladiolus, calla lilies and pineapple lilies (Eucomis), and some elephant ears (Alocasia and certain Colocasia)
- Treat as a houseplant . . . non-hardy ivy and ferns, Plectranthus, elephant ears in the genus Alocasia, cane-type angel wing begonias, Tradescantia, flowering maple (Abutilon), and succulents.
Generally, garden experts recommend just composting some favorite annuals - heliotrope, Lantana, Calibrochoa, Bacopa, Fuschia, and Impatiens. While it's possible to get them to keep going inside during the winter, the success rate is low -- and they're easy and relatively inexpensive to replace in the spring.
I think the most important thing about trying to bring outdoor plants indoors for the winter is . . . that you will have success with some things, and absolute failures with others. I've brought in terrifically healthy Boston ferns for the winter only to have them die in weeks, for example. And every time I attempt to save my dahlia bulbs, they shrivel and dry out. Sometimes I collect seeds and then forget where I put them -- or that I even collected them in the first place. And I love watching my coleus root each winter, but then I usually . . . never plant them in the spring. But last year I got an amaryllis bulb to re-bloom, which I consider a huge win. It's all a crap shoot. It's fun. It's entertaining. It's . . . gardening in the winter!
This year, I have a few "candidates" in my containers for overwintering inside: an elephant ear, a few succulents, and an unidentified tropical annual that's just too pretty to compost. I always take cuttings from my coleus plants and annual salvia, and I plan to collect seeds from my butterfly weed and ornamental onions (and you already know that I've collected some Satomi dogwood seeds). I've also got an ongoing "experiment" with my amaryllis bulbs from last year. It's nearly time for me to bring them in and give them "the silent treatment" now for a few months.
How about you? Do you think you might try bringing any outdoor plants . . . indoors for the winter?
Additional Information and Resources:
For some specific overwintering instructions for a variety of tender plants, this is a great article from Margaret Roach. She also has a great "experiment away" attitude (because, really, what have you got to lose, and this is a fun way to garden in the winter).
Here's a short article with good information about acclimating your houseplants from outdoors to indoors. It also includes some good information about checking for pests.
I know a lot of you love zinnias! Here's a detailed article with instructions for harvesting and saving zinnia seeds. (The same instructions can be used collecting seeds from any number of annuals, by the way.)
Interested in trying to propagate your coleus plant in water? Here are detailed instructions for doing just that from Garden Gate magazine (you'll need to scroll down a bit; first there is general information about growing coleus in planters).
Looking to overwinter some tender bulbs? I know it's kind of fussy and kind of intimidating, but here are detailed instructions with clear photos and recommendations that may help you give it a try. (Just because it's never worked for me doesn't mean it won't work for you!)
Just want to try bringing some plants inside to see if they'll work as houseplants? This article has some step-by-step instructions for how to do that. (I am much lazier than this article suggests I be . . . ) (just sayin).
If you're looking to do some more serious propagation, here's an article listing tools and supplies you might need to get started.
Past Gardening in the Fall posts:
Week One: Less is More (fall clean up information)
Week Two: Now is the Time (fall planting and transplanting information)