Eco-gardening is at its best in The Monday Garden
December 8, 2002 ISSUE #37
“In My Garden” is Braveness, my little Japanese Maple tree, just before moving into his winter home -- a cold frame made out of two orange crates covered in bubble wrap. In the background are ivies under-planted with spring bulbs that will stay out all winter as is. Some people are surprised that I have year-round outdoor plants on a balcony but
any plant that will survive in the ground year-round in your hardiness zone can also survive in a container with a little help.
Temperate-climate plants like Braveness die in the house; they need summer sun and winter domrnacy. In winter, the sleeping plants need protection against short–term temperature fluctuations but must also have circulating air and just enough moisture to stay alive but not rot. A plant that keeps its leaves through the winter also needs light.
Insulators: There are many ways to insulate container pots. Generally you either wrap the pot with an insulator like bubble wrap and/or place it in a cold frame or unheated garage. A couple of inches of bark chips or other sterilized mulch on top of the soil helps too. It’s good to keep the pot off the frozen ground -- elevating it on wooden slats is ideal. As a rule of thumb, pots over 14”in diameter can be left outside without protection other than two or three inches of top mulch. (Note to Maureen and Kim: I won’t try this in Canada!)
Water: A dash of water should be added every week or so to replace that lost to evaporation but be very careful. The right watering balance in winter is tricky. Both over- and under-watering can kill the roots
Air circulation:The wrapping or cold frame should have small openings at the top and bottom to allow air movement. Likewise, top mulch should be loose and airy. An open bottom also assures drainage.
Pots: Almost all types of pots can stay outside. However, most pots can be broken by the expansion of excess water freezing into ice. The best way to prevent breakage is to remove the saucers before first frost and to elevate the pots so that all excess water drains away. If the pot cracks anyway, wrap heavy string around it several times to hold it together. The band of string then adds a decorative element.
Sub-zero temperatures:Braveness likes a cold winter – temperatures in the 20’s and 30’s are fine but below zero temperatures can kill him. I live in a zone 6, so our winter temperatures rarely fall below the teens. However, it can happen. The cold frame will insulate Braveness from the extra cold for a few days. If a longer cold snap is predicted, I wrap several extra layers of insulation around him before the temperatures fell and hope for the best. If necessary, as a last-ditch effort, I’d bring the whole cold frame indoors for short periods – just enough to warm it up to 20F and back outside before defrosting occurs.
Photo credits: Sue Sweeney
© Sue Sweeney 2005