Sunday, October 31, 2010

Tropical Overwintering - An Experiment

Overwintering tropicals can be challenging if you don't have a heated greenhouse. I've had this narrow leaf ficus since about 1990.

Here's what the tree looked like a couple of years after I purchased it.



Each year I have to figure out a way to keep it happy when the weather cooled. A few times I've lucked out and found heated greenhouse space. But usually it ended up somewhere in my house (along with a fair number of spider mites) and emerged in the spring looking non-too-happy.

Recently we moved into a townhouse, which will be our temporary home until are new house is completed. My office area includes a bank of windows that allow in a fair amount of light. Although the space is tight, I thought it offered a good spot for this year's overwintering experiment.

As I mentioned, spider mites are often a problem with the indoor overwintering of this tree. Inside humidity levels are usually quite low, especially with the heating system is running constantly. These conditions seem to provide an ideal environment for spider mites.

To head-off this pest invasion, I treated the ficus several times with highly refined horticultural oil. I also used a non-toxic (but expensive) soil drench to clear out the ant colony that had taken up residence in the pot.

To keep humidity around the tree as high as possible, I purchased an washer overflow pan from HD. Hopefully this reservoir of moisture will help to offset the townhouses dry air.

A few years ago I overwintered the ficus at a bonsai nursery that used propagation matts to boost the temperature in the root zone. The ficus responded well to this set up, so I decided to use a similar approach in my own set up.

I purchased a matt that is designed to warm to 10 to 20 degrees above the ambient air temperature. (It has to be elevated above the water in the tray to work properly, however.) I placed a layer of heavy duty foil under the matt to help reflect the heat up to the pot.

Here are a couple of pictures of what this set up looks like.




If you have any ideas for how to improve this setup, let me know.
  

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