Most of the country is now gearing up for frost. Your flower beds are being prepped for fall and the last of the annuals will soon die with the cold. The beautiful reds, pinks and yellows are now ending but there is no reason many of the plants can’t be brought inside for over winter. A lot of annuals are actually perennials in warm areas, but are considered annuals in a northern climate.
Everyone knows that annuals are well, an annual cost each spring and if you are like my family you go crazy buying annuals each year. When spring arrives, we are so tired from winter and are dying to put color in our yard. Every open spot in the flower bed gets an annual; there are window boxes, containers and even annuals in the vegetable garden. To say the least it takes a pretty penny to have a yard filled with color. Before frost kills your investment it is a great idea to take cuttings, or slips, of your plants. You can raise them inside the greenhouse or in the home. Winter in the greenhouse tends to be very green, without much color, so keeping your annuals alive adds some visual interest. The same is true in the house where houseplants are filled with green foliage.
What plants should be saved? I like to save anything expensive, anything that thrived and looked beautiful all summer and anything rare. You can dig up the entire plant and bring it inside, or when space is an issue, a few branches can be cut and potted for winter. Other plants like dahlias need to be lifted and their bulbs overwintered.
The most common plants to slip are geraniums and coleus. I usually cut a 5” stem of the plant and stick it in a 3” flower pot. Cut off all the blooms and lower leaves so the plant uses all of its energy to re-establish itself. Both of these plants will grow quickly, adding color and blooms to their surroundings. If you bring the entire plant inside, give it a thorough haircut to encourage new growth. Throughout winter the geranium will continue blooming which is a wonderful sight in a snowstorm.
Almost any kind of begonia can come inside for the winter. Tuberous begonias are so beautiful through the summer with their frilly blooms that it kills me to see them die. I have found it easier to dig up the entire begonia instead of trying to slip it. The same is true for bonfire begonias. Both types share a similar soft stem which does not slip well. Angel wings on the other hand are easy to propagate and can be saved with a few stems. Wax begonias are easier to save by digging up the entire root ball and giving the plant a harsh haircut. If any of your begonias grew to outrageous proportions and the thought of bringing them inside is overwhelming you can cut back the root ball, remove a lot of the foliage and make it a manageable size. This will also eliminate a lot of cleanup work as larger plants drop countless leaves.
There are a lot of annuals that are either bulbs or tubers which can be saved: sweet potato vines, caladiums, canas, caladiums, elephant ears and gladiolus. Dig up the bulbs before the first frost and cut off all the foliage. I have successfully killed bulbs such as these by freezing them. I thought my potting shed would be a good space for them to overwinter but it got too cold, the bulbs froze and then turned soft as the weather warmed. To prevent this keep the bulbs in a cool, dark, dry spot where the temperatures do not drop below freezing. This is usually a garage that is attached to a house, or a root cellar.
Several tropical plants can be saved by bringing them inside for winter. Mandevillas, bougenvillas, euphorbia, tropical hibiscus and tibouchina can all be saved by moving them inside. Unlike most annuals you should bring tropical plants inside before it gets too cold. When temperatures drop to 50 degrees at night it is time to dig up their roots. The plants can be dug out when temperatures are in the 40’s but they have an easier time adapting to the indoors with warmer temperatures. Most of these plants will go semi-dormant and that is fine; let them sleep some of the winter. Pot the plant and keep them in a warm location, above 50 degrees. They will drop most of their leaves but do not be shocked; the plant needs to rest so let it drop leaves and look ugly. Fight the urge to overwater and fertilize as this will harm the plant. Only water on occasion when the soil looks really dry.
True annuals will not survive inside so you can let them die and try to save their seed if desired. Petunias, million bells, marigolds, cleomes and zinnias only last the summer. I find it more hassle than it is worth use to try to save the seeds as they are so small and tiny. Come spring the cleome will reseed and seed packets for these plants are cheap, as is buying them as starter plants.
If you decide to keep the plants in your house make sure you have enough space. I put all of my plants in terra cotta pots so they looked nicer but it does mean they need watered almost every day because terra cotta sucks water. If you are comfortable with the temperature in the room, your plants will be happy. Through winter you will have litter as plants drop leaves and flowers so keep this in mind when they are placed throughout the home. Also remember that you will probably overflow their saucers at some point so keep a towel handy. I treat the “slipped” plants like regular house plants and fertilize them regularly, but leave the tropical alone.
Plants you bring into the greenhouse will thrive; they will be nice and toasty with the sun beating on them every
day. An environment of 65-70 degrees F. is ideal, but that can create a high heating bill. Most of the plants can handle 55-60 F. they just don’t grow as quickly. Keep the air moist for them, with humidity around 40-50 percent. They will need plenty of water because the greenhouse can easily heat up even if it is cold outside. It is useful to put the propagations into a “holding” container because the small plants have a tendency to flop over when watered. The strength from the hose knocks them over and onto the floor so I usually pack them into a cardboard box or plant tray. Using a cardboard box sounds odd but you would be surprised how long they last before falling apart. Plus they don’t hold water like a Tupperware container will, and everyone has extra boxes.
As long as you keep the plants warm, fed and watered they will reward you with blooms and growth throughout winter. Come spring you will be ahead of the game and save a couple pennies in the process.
Lyndsey Roth is a frequent contributor to Garden & Greenhouse.