What to do after your garden froze
Wow, after this experience with cold weather it will be harder to speak casually about climate change. This week’s cold spell emphasized that long-term change often includes short-term extremes in the other direction.
What else did we learn? At 11 degrees on Feb. 15, we experienced a low not matched for severity since 1989. The week’s lows had a major impact on our landscape plants and wildlife.
It’s hard to say what brought more damage, the low or the days in a row of uninterrupted below-freezing temperatures. It looks like there were two blocks of freezing temperatures, about 72 hours straight Feb. 14 through Feb. 17, and then another 12 hours Feb. 18.
Over the next few weeks, we will discuss the severity and impact of these temperatures on our landscapes and what to about it. Here’s Part 1.
Cool-weather annuals: It is normal for us to receive a dose of cold weather in January that interferes with the blooming of cool-weather annuals such as calendula, dianthus, petunias, sweet peas, snapdragons and stocks. But usually that amounts to about eight hours below freezing, with a low of just 28 degrees. Such cold spells result in these annuals, most notably snapdragons, pausing their blooming until March.
Another group of cool-weather annuals — pansies, alyssum, cyclamen, primula and ornamental kale — usually blooms through the cold spell.
But this year, I don’t think any of these will stay in bloom. It is likely that unprotected calendula, petunias, stocks, cyclamen, sweet peas and even ornamental kale
were killed by the cold.
You could try to plant new specimens, and they will bloom until May 1. But because they will be hard to find, the most practical tactic to cope is to wait and plant warm weather annuals like zinnias, begonias, moss roses and purslane after mid-march.
Freeze-sensitive plants: One of the usual questions after a freeze is when should we cut out the freeze damage? The answer is to wait a few weeks on the esperanza, duranta, thyrallis and the other semi-tropical plants.
It’s good to wait because the extent of the damage is not immediately clear, and remaining live wood gives us some choices of how large the plants could grow. It also allows gardeners to accommodate the winter songbirds that benefit by any extension of cover, even if it was frozen.
This year the damage to plants will be more severe. Any sensitive plants such as citrus (including satsuma, grapefruit and kumquat) that were not covered and given a heat source will have extensive damage. It is advisable to wait on pruning out freeze damage with the hope that there will be some live wood left.
Unfortunately, even if you covered cold-sensitive lemons and limes with the recommended cloth layer topped by a plastic layer and included a heat source, you can expect some damage. If you did not provide a heat source or if the covering was blown off, you must expect severe damage, including many tree deaths.
Placing the containergrown plant in the garage or other shelter usually works, but even plants in the unheated garage could have experienced damage.
We will continue the discussion next week, including the impact the cold had on winter birds and cold-tolerant trees and shrubs.