What to do with your plants in this cold weather

Monday, January 4, 2010

This week is bringing the coldest weather we’ve experienced in nine years.

To help prevent cold damage to your plants, cover tender plants, either with old sheets, paper or boxes. Do not use plastic, as any plastic touching leaves will carry heat into the atmosphere away from the plants.

At night, a floodlight beams heat into the covered sealing wax palms.

I have covered the tender palms, such as the sealing wax and Pelagodoxa henryana, with sheets and put floodlights beneath the sheets to help protect them at night. The plastic on the sides of the orchid houses has been rolled down, and we have convection heaters and flood lights going inside all night.  You can run water across the floor of your covered house to keep the temperatures up if you don’t have heaters. Mist systems installed beneath orchid benches are one way that commercial growers keep their orchids warm. When the sun warms the interior of your plastic-covered shade house, open a vent near the ceiling to let out hot air.

All the vandas have been moved from their trellis into a covered shade house and are sharing space with bulbophyllums and slipper orchids. We are not watering for the duration, but I will slip beneath the plastic into the house and mist the Vanda roots tomorrow.

Fortunately, I gave all the orchids a fungicide spray last week after stocking up on Dithane M4 and Thiomil (a systemic fungicide) and Kocide, an antibacyerial copper-based product. When warm weather returns, it’s a good idea to spray orchids with a mixture of Dithane M45 and Kocide, 1 tablespoon each per gallon. (Avoid using copper on bromeliads as it can be toxic to them.)

Sheets in the garden signal
cold weather.

If you live in an area that is touched by frost or freezing weather this week, this same mix can be used on your palms to help prevent crown rot. Just pour it right into the growing point. Another strategy for especially tender small palms is to wrap the crown with sheets of foam to protect the heart.

Watering the ground during the day to allow the sun to heat it is a good idea as well. Don’t water the leaves of plants. If you have hanging baskets in a tree, for example, pull back mulch and water the area beneath the canopy. This will help create a warmer microclimate at night as the soil releases its warmth.

Bring inside those plants you value. I have brought in all the vandaceous orchids in flower or bud (as well as some that are prized favorites), the amaryllis, poinsettias and tender aroids, such as Philodendron tenue and Philodendron regale.

Inside also are the parrots, and they’re not at all pleased.