15 August, 13

Successfully Overwintering Tropicals

Tropical plants will suffer from the night-time temperatures below 40 degrees F. Plan to bring in your houseplants when temperatures are forecast below 45 degrees F to protect them from cold damage.

Successfully Overwintering Tropicals – printable PDF version

Before Bringing Your Houseplants Inside

In early September or sooner, get the winter growing area ready by washing windows, inside and out; putting up shelving; and setting up humidity trays. If plants need repotting, sterilize the new pots and have soil and fertilizing supplies ready.

Inspect the tops and undersides of plants, the stem, and soil before returning them inside. Treat them for found pests while still outdoors as appropriate. Outside the pot or on the bottom you may find unwanted inhabitants. To lure pests out, soak the pot for 15 minutes in lukewarm water. If too many emerge from the soil, consider repotting with fresh soil and place fine mesh screen over the bottom hole to limit access next summer.

Now is a good time to take 3 – 4 inch cuttings of annual flowers, such as impatiens, begonias, geraniums or coleus. Choose healthy new growth. These root easily in damp sand or even a glass of water. A quick dip in rooting hormone helps as well. Transplant into small pots after roots appear.

You will want to acclimate your plants gradually to conditions indoors. Sudden changes in temperature, light and humidity can bring on yellowing leaves, stem dieback or even plant death.
If night-time temperatures are forecast below 45 degrees, move plants into a protected area away from drying heat sources. Allow air circulation from a window during warm days. Gradually increase the time spent indoors, just the reverse of hardening plants in spring.

Try to mimic the plant’s outdoor lighting conditions at first to prevent shock. Usually plants will lose a few leaves if the light changes dramatically but new ones should form as the plant adapts.

Overwatering may be the biggest initial problem. Let the soil surface dry to the touch before watering again. Lower light levels and less direct sunlight mean the soil will not dry out as quickly. Readjust your watering routine accordingly. Remember, a humidity tray (see more below) will be needed as indoor heating systems start running later in the fall.

Finally, encourage plant health with a boost of fertilizer and help it cope the stress of a new location.

General Tips For Winter Houseplant Care

By thoroughly inspecting the tops and undersides of plants, the stem, and soil at least once a week, you can catch the first signs of insect or fungus problems.

If your plants are losing leaves or are turning yellow

don’t necessarily blame insects or fungus yet. Drastic humidity swings could be the problem. Bring up the humidity without over-watering by placing trays filled with gravel under your pots. Keep the gravel moist and you create a humid environment for the plant. Investing in a small electric humidifier will benefit not only the health of your plants but your health as well. Only water when the soil is dry to the touch.

Plants still looking blah?

Common pests include aphids, white fly, fungus gnats, powdery mildew, and spider mites. The white fly lays its eggs under the leaf in the shade of the plant. Don’t forget to inspect thoroughly. You’ll find a magnifying glass is a great help. A little reflective foil placed around the base of the plant will help prevent the white fly from laying eggs there. To get rid of them as well as aphids, give your plants a thorough bath in the shower. Spray insecticidal soap or horticultural oil to coat the leaves including the undersides. When plants are dry, return them to their usual location. Inspect in one week and repeat the process two more times, about 7 days apart for a total of 3 applications. This will break the lifecycle between egg stage and adult. Using a yellow sticky card will help monitor the flying insect population and also give some control.

Powdery mildew

the white dusting on plant surfaces, occurs from dramatic swings in moisture and lack of air circulation. Treat with a fungicide spray labeled for powdery mildew. Home remedies include baking soda and water about 1 tablespoon soda per gallon and chamomile tea applied at room temperature at weekly intervals until all signs are gone. Coat undersides of leaves, too. To prevent the mildew, again keep your humidity around the plants stable and don’t pack plants too close together. Light pinching will also allow better air circulation.

Spider mites

love the dry air of winter. Yellowing, stippled leaves indicate this parasite may have moved in; wispy web strands between leaves and leaf stems confirm them. Still not sure? Hold a white piece of paper under the plant leaves and tap the stem. Dust specks that land on the paper and move under their own power are mites. Again, give your plants a thorough shower and use insecticidal soap or horticultural oil to coat the leaves and soil surface. And try to increase humidity or mist daily!

Continue to fertilize weakly.

Use half-strength to quarter-strength fertilizer. Plants kept indoors will start to react to the longer days and may put out new growth. Pinch this growth back to prevent long “legs” and to make a bushier plant. You’ll want to continue this practice until at least April.

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