Tropicals & Tender Perennials: Rust Fungus?, 0 by Clare_CA

Clare_CA wrote:
Hi Michelle, how handy it is to have a hubby that likes science and is interested in the weather! This is very important information for us growers!

Sure, you can just plant them, pot and all, in the ground. That is called "plunging," and I did it with about 20 of my seedlings this summer (see pic below). When you plunge, the roots grow out the drainage holes, and if you have to bring the pot up before a frost warning, you will break some roots in the process. This won't necessarily be bad, especially if the plant is already dormant, but it might be easier to just grow your plumie in a pot above ground and bring it in when there is a frost warning, or you could throw a frost protecting cloth over it if it is planted in the ground. Some people put Christmas lights on their trees during frost warnings, but I don't know if that really protects the tips or not.

I had many trees outside when it hit 36 for a few hours one day last winter. It made me very nervous, but I saw no damage anywhere. I think yours would be okay if it only got down to 34-36 for a very brief period, like a few hours, but anything at freezing or below will cause the tree to die back from the tips. Plumies can come back from light freezes if the tree gains some maturity and some cold tolerance over several years, but a hard frost will turn a plumie to mush.

There are things in the yard which will raise the temperature outside and which will create microclimates around your plants. For example, I have three-quarter rock instead of grass, aluminum siding on the house, and a six-foot brick retaining wall surrounding the yard. All of these things absorb heat during the day and radiate it at night and create a nice little microclimate in my yard. This is one way to raise the zone you are in by a half zone to a full zone.

Tillie Hughes is a nice one. Check out Page 28 of this link: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/OF-31.pdf