Just when we had allowed Spring Fever to really get the best of us, buying plants, cleaning the winter accumulation, trimming, and even mowing, along comes the freeze — a killing freeze in some places with only mottled frost in others. Out come the old sheets and blankets covering our most beloved and dotting our landscape like a bad modern art painting.
With below-freezing temperatures, water in plant cells freezes, forming ice crystals that expand. This expansion ruptures cell walls. The effect is similar to pricking a hole in a water-filled balloon. The special “glue” holding the plant cells together leaks out and the plant cells collapse.
Many plants can withstand a short period of freezing, while others can’t at all. Begonias, impatiens, tomatoes and peppers are toast. Pansies, leafy vegetables, crocus, daffodils tend to look bad the morning after but recover quite nicely. Their location — high ground, low areas, up against a house or wall — will determine the extent of the damage.
The damage may not appear immediately. Small pockets of leaf cells may be damaged, and as the plant grows holes, wrinkles or under-developed leaves will appear. We see this later and immediately think it’s caused by insects or disease when in fact it was the late frost. Mark the freeze date in your garden log and refer to it later.
Woody perennials and trees may lose leaves, only to be replaced as the season progresses. Conifers including Norway spruce, Colorado blue spruce, white pine and fir are not immune. They have also put out new growth. Do not be tempted to prune damaged trees, as in most cases they will recover on their own. Fruiting trees or vines may have lost some primary buds but may develop using the secondary or tertiary buds.
One of the biggest issues with this late cold is the soil temperature. It just does not warm up as fast, and certainly not as fast as our eagerness to plant.