Saturday, April 28, 2012
Frozen But Not Frosted
At 5 am this morning the air temperature was 24F. Inside of the sod house at ground level the temperature was 30F. No frost was seen anywhere but bare ground was frozen to a depth of 1/4 of an inch. Quite surprisingly unprotected plants appeared largely undamaged. It appears that frost is far more damaging than a freeze. We are trying to understand the science behind frost but it may be that heat given off when water vapor goes directly from a gas to a solid may actually burn the plant leaves.
These orange spotted lilies were placed in pots four weeks ago. Protection from the cold has been provided by moving the pots into the basement on cold nights. The clumps of lilies in the second picture are where we dug the potted plants. A plastic tub covers these lilies on cold nights. Despite the shock of being potted, the warm nights in the basement have prompted faster growth. Aside from the time and effort to move the pots in a night and out in the morning, potting the lilies seems like a workable way to protect them from the cold.
The sod house is working better now that we have a more secure way to tie down the tarp. Rope lashes the ends of the tarp to steel posts that lie on the ground. Water filled juice bottles still weigh down the tarp at both the front and back. Four holes show the former location of favored lilies that were pulled from the ground and placed in the basement overnight. It seems that we over protected as all of the lilies in the sod house are fine.
These are some of the plants that spend their days basking on the stone wall and their nights in the basement. Some of these plants are newly purchased while others were dug from the garden. Cardinal flower, Lobelia cardinalis, is dug from the garden each spring. The plant is native to New York State but I have never seen it growing wild around here. I have seen it growing in the Delaware River valley to our south. Frost frequently kills plants left in the garden so some are potted up and spend nights inside.
Shade cast by the house limits these really new arrivals from sunburn. We will increase their time in the sun slowly until the are ready to be planted out. One more month stands between us and the usually frost free date of June first. We look forward to warmer nights when the plants can be left outside over night.