UNITED STATES—Frost was something of a non-issue for some of us this winter. For those of us in milder climates, it rarely is. Those who limit selection of what grows in their gardens to species that are resilient to frost need not be concerned with it. Those of us who enjoy gardening a bit too much are more likely to grow a few marginal species that would prefer to be somewhere with milder winter weather.
Protection from frost might have been a concern prior to the onset of cold weather. Then, there was more concern for the few plants that might have been damaged by frost. Grooming and pruning of damaged foliage and stems needed to be delayed until after the threat of subsequent frost. Now that it is so late in the season, subsequent frost is very unlikely. It is safe to clean up any mess.
Pruning and grooming of foliage and stems that were damaged by frost is delayed for two main reasons. Firstly, the damaged material, although unsightly, helps insulate undamaged foliage and stems below it from subsequent frost. Secondly, premature removal of damaged material stimulates premature development of new foliage and stems that are more sensitive to subsequent frost.
Not only is it now safe to prune and groom frost damaged plants, but such procedures should not be delayed while affected plants recover. The same frost damaged material that provided a bit of protective insulation earlier would now interfere with the healthy development of new stems and foliage. Pruning can now promote new growth that was preferably delayed through colder weather.
Because the weather has been so pleasantly mild for quite a while already, new growth may already be developing among some frost damaged plants. Damaged material should be removed as carefully as possible to limit damage to such new growth. Many perennials that were not damaged this year might be pruned as if they were, to remove tired old growth, and promote new growth.
Many of the dormant spores of fungal and bacterial pathogens that overwinter in old foliage will be removed as such foliage gets groomed away.
Highlight: sword fern
This is not the native Western sword fern of forested and riparian regions here on the West Coast. This sword fern, Nephrolepis cordifolia, is native to Northeastern Australia, Southeastern Asia and Hawaii. It is naturalized in many regions beyond its natural range, and is considered an invasive exotic species in some regions. Its resiliency and reliability are appreciated in local gardens.
If it resembles the popular houseplant, Boston fern, it is because this sword fern is of the same genus. It just happens to prefer to be out in a garden rather than inside a home. Much or even most of the light green foliage stands more upright, rather than cascading from pots or elevated planters. Foliage of mature plants can get almost three feet high, with an even broader horizontal reach.
In fact, sword fern is notorious for sneaking around the garden and spreading wider than just a few feet. It is not particularly aggressive about. It creeps slowly, but steadily until someone eventually notices that it has gotten a bit too prolific. Their abundant runners are wiry and strangely hairy, and produce small round tubers. Foliage can be yellowish if not watered enough in sunny situations.
Horticulturist Tony Tomeo can be contacted at tonytomeo.com.