Plants that need a winter rest include banana, begonia, caladium, calla, canna, colocasia, dahlia, ginger, gladiolas, and sweet potato vine. Don't let a cold North Dakota winter kill your favorite tender perennial plants this year. Bring them inside, quarantine them, and keep them as houseplants for the winter.
Giving your plant a good rinse is a good way to remove dust, dirt, and any bugs that might be hanging on before bringing it into your home. This is also a good time to give your plant a deep watering. Consider the plant's needs when placing them indoors.
Just to be on the safe side, I also take cuttings of some of my favorites—like the iresine, begonias, geraniums, impatiens, and coleus. All will root easily in water and make attractive houseplants. If you lack space to store pots over the winter, cuttings are a wonderful and inexpensive way to create more plants.
Outdoor Plants for Indoors
Although most people use plants such as impatiens, geraniums, ageratum, dusty miller, wax begonias, and coleus as summer annuals that die off once the first frost hits, these plants can easily be grown on a sunny windowsill to provide indoor color all winter long.
Some experts recommend bathing or soaking plants in a bucket of water with mild dishwashing soap before bringing them inside. If your plants are too big for the bucket treatment, spray them with water to remove outdoor dust and soft-bodied insects from the leaves.
Take Special Precautions for Potted Plants
To protect them, you can wrap the pots in an insulating material (think burlap, old blankets, or even bubble wrap), place them close to the foundation of your house, and arrange them close together. You can also put a layer of mulch over them for added protection.
Store Your Perennials Indoors
An unheated garage, shed, or basement with a temperature range between 30 and 40 degrees can provide a perfect environment for overwintering perennials.
Annuals that do well indoors during the winter are limited to Coleus, Impatiens (including New Guinea), Nasturtium, Pansy Petunia, Verbena, Wax Begonia, Lantana, and Geraniums, with Coleus and Geraniums being the easiest. Gardening is about experimenting so try any annual you'd like.
1. In order to overwinter a perennial or shrub in a container outside, it needs to be two zones hardier than the zone you live in. 2. Perennials and shrubs that are in your zone or one colder can be overwintered in an unheated garage, buried in the ground, or transplanted.
Even if you don't see any bugs, their eggs could be hiding in small cracks between leaves, ready to hatch in the warm indoor temperatures. It is a good idea to spray the whole plant. There are may DIY products like dish soap, hand soap, Castile soap, Neem etc., but the safest option is insecticidal soap.
You can also use a pressurized sprayer to apply water to leaf surfaces. For small specimens, consider dunking the entire plant into a 5-gallon bucket of water for 15 minutes. This will cause insects on leaves or in soil to flee. Add a few drops of liquid dish or hand soap to the water as a further deterrent to insects.
Make sure to turn over leaves to check the undersides and look closely along the stems. Spray any pests you see with insecticidal soap ($10, The Home Depot). Even if you don't spot any bugs, just in case, wash your plants with a strong spray of water from the hose.
Fall is a great time to do maintenance on your houseplants, so they are rejuvenated by spring. You will need to bring your plants indoors before nighttime temperatures dip below 45 degrees (F).
Quarantine your plant.
“When you bring it home, set it in a quarantine area for a couple of days before you mix it with your other plants," says Satch. "Don't worry if it's not by a window, they can take that kind of light condition, only for a couple of days before they start dropping leaves."
Also, if you discover that a houseplant is pot-bound, repot it into a larger container before moving it inside. That way the mess will stay outside. Debugging and cleaning potted plants before bringing them back inside is a crucial step to avoid houseplant bug problems.
Unlike perennials, annuals do not come back from season to season so there is no reason to leave these in the ground. Pull them up, roots and all, and add them to your compost pile. Remove weeds and leaf debris. These are common places for diseases and pests over winter.
You can put them in a garage or shed that gets cold but doesn't freeze, ever. They will over-winter as live but semi-dormant plants. Keep the soil just moist, not letting the potting medium shrink and pull away from the pot edges.
Perennials NOT to Cut Back
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
You can overwinter potted perennials in an unheated shed or garage. Allow them to naturally go dormant in the fall before moving them inside. Then put them back outside once the weather starts warming back up in late winter or very early spring.
The outdoors is full of insects that also want to enjoy our plants. Before you bring them in, you can spray you plants lightly with a hose or inside shower to knock off any insects or dirt. Be careful to not blast them with high pressure as to not damage foliage.
Vegetable Oil
Use 1 tablespoon of mild soap (like dish soap or castile soap) to 1 cup of vegetable oil. Mix well. Add 2 tablespoons of the oil mix to 1 quart of water and pour into a spray bottle. Spray the top and bottom of each leaf where the insects are dwelling and the stems if needed.