Cold Weather Is Just What Your Garden Needs

The plants in my house get watered on Sunday morning. For many years, plants were not allowed in my house as I have a reputation for killing indoor plants. But these plants are some of my favorites and they needed rescuing. Some came from the greenhouse at my last job: the unusual sanseverias, that huge rare agave, the nepenthes, two Rex Begonias, and some select succulents. Some came from clients’ pots, on their way to the end of season garbage: a clivia, a large flowering hibiscus and two pitiful geraniums. And some came from garden centers, also headed for end of season garbage: four scented geraniums I am “topiary-izing” and a snail vine that may or may not make it until spring.

I loved working in the greenhouse in the winter and while this is not the same, it has its merits. With warm temperatures, the pots will go outside and the house will again be serene in the absence of plant responsibility.

The snail vine has spider mites, not uncommon for this kind of plant when kept indoors. One day was so warm that I was able to treat it to a trip outside.

As I remember, late January is supposed to be cold, with a good month of cold preceding it and with perhaps a good layer of snow. Cold is necessary for temperate perennials, trees, bulbs, and some seeds. They have entered their dormancy based on the amount of available sun. This stops their active growing in anticipation of coming cold. It is cold that breaks dormancy. During prolonged periods of warm weather and as the days lengthen, dormancy is interrupted and plants can begin to grow and buds can open. If this spell is followed by cold, the plants can be damaged and buds for that year are gone. These circumstances are especially dangerous for fruit trees and cause decreased production.

These kinds of plants also need to be vernalized. They actually need a certain amount of cold, depending on the variety, to make flowers and to make them at the appropriate time. Peonies, iris and lily of the valley, three of my favorites, especially need cold.

Biennials need cold to make flowers and set seeds. There are hollyhocks, digitalis, rose campions, and verbascums in my garden. Biennials like these tease for one year with large green mounds, promising flowers the next year. They need to be vernalized to make those flowers.

Periods of warm weather followed by sudden cold can cause plants to “heave,” lifting them from the soil and thereby putting their roots in danger. Mulch is recommended to prevent heaving and moisture loss. The recommended application time for mulch is after the ground freezes. However, I am assuming that gardeners applied their mulch in anticipation of cold. If the mulch lets water come and go from the soil, it should be good. Compost is always good mulch. I use leaves in my garden and the plants thrive.

As I drive around the area, I notice many evergreens that were very damaged in the superstorm with large portions of dead-looking brown on the sides facing the storm winds. The same happened in the last storm. The trees seemed on their way to recovery after that but I wonder if the stress of two large storms so close together will allow them to recover now.

The warm winter will cause them more stress. If cold weather came slowly and remained for several weeks with a slow warming period, the plants would be happy but that should happen soon.

Do not yield to the temptation to prune now as the weather entices—wait until late spring to avoid damage to the plants. I am also going to wait until spring to do any further cleanup, leaving dead plant material as mulch.

Let us hope for more cold—the plants will be happy.

Jeanelle Myers is a professional gardener and consultant. For gardening discussion you can call her at 631-434-5067.

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