How to bring summer annuals inside and reduce your footprint
Living in Lethbridge can be difficult as a hard-core gardener. Even though 80% of Canada saw an increase in hardiness zones this year (we mostly got warmer), southern Alberta can only grow outside for a portion of the calendar year. Still, Canadians and Lethbridge residents like to beautify their outdoor spaces with annual containers spilling over with tropical plants and vines for the warm season. Many of us also move our houseplants outside to augment their growth and allow us to keep the curtains closed during the hot summer months. What happens to those summer annuals you purchased, though? Do they go into the green bin? The garbage?
The international horticulture industry has several key environmental concerns, including soil degradation, water use and quality, and greenhouse gas emissions. Furthermore, there is increased risk of human health concerns (specifically for workers) due to high chemical use. While there might not be a more beautiful space than a greenhouse full of annuals in Canadian spring, all that bright colour comes with a dark side. If you are concerned about your consumption from this industry, you can start to make a change this fall and bring some of your favourites in for the winter.
Every houseplant is a perennial somewhere. In fact, many of them are such aggressive growers that they are listed as prohibited invasive weeds where winters are temperate (including the warmer areas of Canada). These include such favourites as the spider plant, arrowhead plant, Swiss-cheese plant, and the small-leaf spiderwort (although none of these are risks in Lethbridge). Many common houseplants are actually shade lovers and can be moved outside to an area with mild morning sun or constant shade. Did you know that several of the annuals you purchase every year for your outdoor pots can also move in?
I prefer to grow really large plants that spill and crawl over the deck, so give single plants big pots and therefore don’t purchase many aesthetic annuals (in fact, I like to start many flowering annuals from seed – watch for that article in the spring). Every year I’ve been purchasing even fewer because I’m putting my houseplants outside after last frost in spring and bringing an increasing number of tropicals in before first frost in fall. It’s a jungle inside in the winter! Here are a few annuals that I’ve transitioned to living inside through the frigid months:
Variegated Creeping Charlie: a member of the mint family with a fresh, lemony smell and delightful, coarse leaves with white edges. I love this plant. I grow it in an eight-inch clay pot every summer and in September, I take cuttings from it and let them root in water. Be careful with this one, even in southern Alberta, as it is invasive and a prohibited weed in Ontario and many growers have it listed as a zone 5. Keep it in a pot.
Purple Swedish Ivy: This plant is a true shade lover and does just as well in the house as it does outside on the front porch. I keep one in a pot that moves in and out and break off pieces, just setting them in an annual pot in the spring (usually with begonias). They fill in beautifully through the summer and need almost nothing. It will expire if it gets frost, though, so don’t take chances by leaving it outside late.
German Ivy: I can’t decide if I like it or not but have kept it for several winters now. It is a prolific grower and drinks too much but it can fill up a gloomy corner with a lot of green (and even flowers in the house). This spring, exasperated, I put it outside in a large pot (to hopefully ignore it) and it filled in so fast that I had to sit it in water by mid-July! Last week, I dumped it out of the pot and sliced through the huge root ball with a shovel. That small chunk of plant and root is in now an 8″ pot and it didn’t even slightly wilt from the abuse. Extra points for toughness! Cut it back before you put it outside next spring!
Dorianthus Mizoo/Red Livingstone Daisy: One of my favourite full-sun trailers. It’s a bit finicky to get into a smaller pot because it likes the hot sun and grows exponentially over the summer: some of its bigger leaves flopped in protest but are gradually making a comeback. It grows happily inside in a south window.
Pineapple mint: in addition to Creeping Charlie, I grow all manner of tender mints in pots because they smell amazing. This mint also has variegated leaves! I just take cuttings and let them root in water before popping them into small pots to wait for spring. You could also slice the root ball, as with the German Ivy, and downsize your pot.
Rosemary: If you’re like me, you can’t do without this herb in the garden and every year they’re getting more expensive and harder to find. Rosemary is troubling to bring in because they are a woody herb and get massive during the summer. I to dig it out of its garden spot, wash the root ball off, trim it down, trim down the plant by ⅓ and repot. Rosemary never enjoy the house but perhaps Lethbridge is getting closer and closer to being able to overwinter these tender herbs outside. I’ve known a couple folks who have gone to great lengths and been successful but I’d rather have fresh rosemary all winter (it’s great with roast root vegetables).
Try your own favourites: there seems to be endless advice on transitioning nearly any annual/tender perennial you can think of to houseplants on the internet. Give it a try! This article has covered the simple transitions, but there is also plenty of advice on rooting woody plants, if you’re so inclined. Be your own grower! Remember you don’t need much room: you generally buy ornamentals in 2″ pots. Keep them small and watered and see what happens next summer!
A word on fungus gnats: bringing soil indoors makes these harmless but annoying (and prolific) insects almost unavoidable. One way to stop them from starting is to wash the root ball entirely free of soil, repot in fresh, sterile potting soil, and bring indoors immediately. Because I have so many plants making the transition now, I prefer to use one part 3% hydrogen peroxide to four parts water and top-water with that solution until the gnats are decimated. It has never taken more than two treatments to effectively treat my susceptible houseplants (I also use sticky yellow traps to catch the adults). It’s helpful to be prepared well before first frost and grab a bottle of 3% peroxide to have handy. It’s considered a harmless and environmentally-safe pest management (check out some other uses here) and in my experience, it works quickly.
Good luck overwintering your summer crop of beauties!
