Plants In Winter: Why Chilly Weather is Good for Landscapes

Reading Time: 4 minutes
landscape crews pruning plants in winter dormancy
Garden management crews perform dormant pruning and cutbacks, and inspect for winter damage

Consistently cold weather is good for plants in winter when they are dormant.  It gives them time to “rest” between growing seasons. However, if the temperatures are inconsistent, that can cause problems.

An unusually warm winter with irregular temperature swings between freezing and warming may interfere with the “beauty sleep” your plants need to regenerate.

For example, in past years we have seen shrubs and trees display signs of winter damage. Although it may look bad, you needn’t be overly concerned.

Your landscape plants have an amazing ability to self-correct. And with a little TLC from your landscape maintenance crew, most of them will bounce back to where they were.

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How Irregular Weather Affects Your Garden Plants in Winter 

Several years ago we experienced some out-of-the-ordinary temperatures that caused winter damage to some plants. Two conditions caused this:

  1. an extended warm period until late in the fall followed by an abrupt plunge into freezing temperatures
  2. extreme fluctuations between warm and freezing temperatures

 

Here’s how each of these conditions affected your landscape shrubs and trees.

bark split by temperature fluctuations
A rupture in the bark of this arborvitae limb caused by temperature fluctuations

1 Extended Warm Spell

If an extended warm period maintains the soil temperature at 50 degrees or above, plants will start to grow.

A few years ago, we observed roses with full green foliage – in December! Some were still blooming. Because of the unusually warm weather, they hadn’t gone dormant yet.

When the temperature suddenly dropped to freezing, a lot of those roses got tip burn that killed the foliage and turned it brown. Some customers were concerned because their plants suddenly looked terrible.

Normally, we’d have pruned roses well before then. We wait for them to enter dormancy to trim away diseased or dead branches because it’s easier to see them once the foliage is gone. Since they were still going strong, we waited to perform scheduled cutbacks.

By the way, the new green wood is the flower-producing part. Artful pruning at the right time of year encourages new (flower-producing) growth. You can prune roses any time of year because they are hardy. But we save the aggressive pruning (about 50% cut in height) for January or February.

An abrupt temperature change during an extended warm spell would shock a plant because it was responding to warm weather as if it were still in its growing season (but was not!). The plant may suffer because it did not experience the gradual transition into dormancy that prepares it for the hard freezes (mid-20s) that normally start in November.

Laceleaf Japanese Maple in Winter

2 Extreme Temperature Fluctuations

Normally, when a plant enters dormancy, the sap drains back down into the roots. The cell walls in the branches and buds thicken up. We call it “hardening off”. This prevents the cell walls from rupturing when temperatures drop to freezing.

If plants come out of dormancy and continue to grow there will be sap in the branches. Those cell walls may rupture and the buds break as the sap expands and contracts with the temperature changes.

Some damage to plants in winter won’t appear until April when the sap rises and the landscape comes back to life. Those of Southern origin such as the crape myrtle, holly, fig, gardenia, magnolia, camellia, and nandina may not look as full when they start to bloom in the spring. Why is that?

Even though bred to be cold tolerant, cultivars of Southern origin are vulnerable to the extreme conditions we experience in the Mid-Atlantic region. So in April, you may see fewer or no blooms. The damage may be unsightly but is not permanent. Your garden care crews will simply prune the dead material in spring and let the plant regenerate over the summer. 

Plants in Winter and Summer: How We Optimize for Hardiness

Plant Selection

A gardenia showing signs of tip burn
This gardenia shows signs of tip burn because it had not fully entered dormancy when cold temps hit. It will recover.

There are particular plants that we use in landscaping over and over again because people love them. And they look great in your gardens. To maintain balance, we always work with a 60/40 mix of natives (those that naturally grow in our region) and cultivars of plants that originate in nearby regions.

Here in the mid-Atlantic, we are in a transition zone where warm climate plants give way to cold climate plants. The cultivars we plant in your yard, a mix of Southern and Northern origin plants, are carefully selected for their versatility and adaptability to our region.

The Role of Cultivars

Cultivars are constantly being developed by growers and college extensions to take hardiness traits from a related plant and put them into the desired landscape plant. They may breed them for cold tolerance, heat tolerance, or disease resistance. 

We use cultivars of northern-origin plants bred to tolerate heat and humidity. We use cultivars of plants of southern origin that are bred to tolerate winter cold. The breeding of cultivars extends the range of the origin plants making them more versatile and able to do well in our region.

Although we have no control over how Mother Nature will treat our plants in winter, we have learned over time to be adaptive and proactive in the areas of garden design, plant selection, and garden care practices. With good planning and regular landscape maintenance, we are able to maximize the beauty and longevity of the types of outdoor environments our customers ask us to create for them.

Have you been wondering how to bring out the fullest expression in your landscape and gardens? Our eBook: Choosing the Right Kind of Landscape Maintenance Firm, is full of valuable information to help you understand the fundamental differences between landscape maintenance companies.

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