Protecting Cycads and Other Plants from Frost
Protecting Cycads and Other Plants from Frost
In California, we had a late-winter cold weather snap that extended through the Southwest, threatening the cycads and succulents and other drought-tolerant plants we grow. It was the worst cold spell since 2007 when many plant growers, both home and commercial, lost leaves and plants. Parts of Los Angeles and surrounding areas got below freezing, and we had snow in parts of Southern California as low as 500-1000 feet. We had a hail shower at the house, but it missed our nursery.
If you have outdoor plants like us, here are some basic steps to take before a potential frost and after:
1. Cover tender plants with frost cloth. Hopefully it hasn't sold out everywhere at this point. Check your local nursery or garden supply store for availability. Using an old sheet is better than nothing, but frost cloth is preferable.
2. Most plants could benefit from a small watering as part of your preparation, but NOT cactus and other water-retaining succulents. As you know, water expands when it freezes. If the cells of your succulents are full of water, they will burst when the water freezes, killing the plant. If they're a little low on water when the cold arrives, there's a chance the cell walls will be able to stand a little expansion and won't burst.
3. Bring inside as many of your container plants as possible. If they don't fit inside, placing them against an outside wall of your house or apartment, particularly if there's an overhang, can make a big difference. We brought several species into our greenhouses which normally remain outside, such as some of the central African encephalartos (Encephalartos kisambo, Encephalartos gratus and Encephalartos manikensis), tree dioons (Dioon spinulosum, Dioon mejiae and Dioon rzedowskii), subtropical zamia like Zamia furfuracea, and a couple of Ceratozamia species. We also brought in recently potted aloe and aeonium succulents.
4. Mulches can protect your plants by moderating root temperatures and preserving unfrozen moisture. By protecting the caudex and roots, they have the effect of a blanket, in terms of relative warmth.
5. Here are some additional tips on How To Grow Cold-Tolerant Plants via a slide show on our website: http://www.cycadpalm.com/howtogrcocyi.html
What should you do after a freeze?
1. Be patient. The cold spell in January 2007 was tough on plants, but more made it through than we originally thought. Although we found that many plants had experienced leaf damage, the roots of these plants had survived, and in the spring and summer, fewer than 25% of plants suffering leaf damage had not recovered. By late summer, the number went down to 10%. We lost some plants, but not nearly as many as it looked right after the freeze.
2. Do not prune or cut back plants too hastily. In case of another cold spell, an unpruned plant helps provide insulation for its roots and main trunk. Also, pruning too early could force the plant into growth, which would stress the plant and force it to use of more of its reserves, leaving it vulnerable to weather and pests.
3. Wait for new growth on woody plants to actually know what's dead.
4. Water only if dry. If roots are damaged, over-watering now can encourage root injury.
Please Note: It may take several months for new growth to appear.
Also, please consider keeping notes on the damage that occurred for your own reference, and the benefit of others.
* This posting was originally published in early March 2011, in advance of a frost warning for California and the Southwestern USA.