The Cold, Hard Facts on Protecting Potted Plants
Tips for helping your potted plants survive winter.
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Find the right place
A pot's location also determines how well plants are protected. Place containers on the north or east sides of the house where conditions are typically shadier. Southern exposures tend to have the greatest temperature swing.
Hardy dwarf conifers, evergreens, ornamental grasses and trees or shrubs with interesting habits or bark colors are great for adding winter interest. If possible, place pots with these plants near a window or front door where they'll be easily seen.
How to water during the winter
Because there's typically less rainfall in winter, adequately water your pots. Broadleaf and needled evergreens are particularly sensitive to desiccation. The ideal time to water is during the day when temperatures have warmed above freezing. If the forecast predicts windy or freezing conditions, try to water before these conditions occur.
"When water freezes, it gives off heat. There's a latent heat release," Hannah says. Water provides some warmth to the root zone. Frost penetrates deeper into the air spaces of dry soil than moist soil because, in moist soil, water has filled the air pockets. Hannah suggests that even if temperatures are at freezing and the pot is dry, it's important to water because it will help to better protect the plants' roots.
"When plants aren't properly overwintered, they'll have problems come spring," she says. For example, a plant may not break out of dormancy or it will have delayed bud break. Or, it may begin new growth at the start of the growing season, but if the roots can't support this growth, the plant dies. Even if container plants are able to make it through winter, they may have slowed growth, developing very little by following fall.
Overwintering options in the outdoors
Depending on where you live, it may be necessary to provide added protection for your pots. Here are several options for overwintering containers:
For USDA Zones 7 through 11, hard freezes may be infrequent to nonexistent, so adding insulation or bringing pots in for the winter may not be necessary. However, there are some chores that you should still be aware of. Due to cooler temperatures in the winter, plant growth will slow and watering may become infrequent. However, salt can build up in the soil, raising levels to toxicity. Water well to leach out the salts. Also, fertilize plants as needed.