Protecting plants from freezing and from the cold

As frost creeps into a plant, the water in its sap crystallises, swells and bursts the cells from the inside — yet it usually takes a long, very cold spell rather than a single frosty night to kill outright. A bedding of mulch over the roots, or a wrap of horticultural fleece, buys the few degrees that decide survival.

It is important to protect them from the cold and from freezing so that they may burst with life anew in spring!

A few simple protective measures can be practiced to help you protect them easily at the lowest cost.

• Read also: using mulch to protect plants from the cold in winter

How to protect plants from freezing

Deciduous plants, those that lose their leaves, practically cease any form of activity over winter, and are much less vulnerable to the cold.

It isn’t as important to protect these, even though some plants would appreciate mulch prepared from dried leaves or bark.

It is always best to grow plants, trees or shrubs native to your area, because they never fear local winter events.

• Keep mulch from touching the trunk, leaving a clear gap of roughly 8–15 cm around the base of most trees, and up to about 30 cm for larger, mature specimens.
• Shred or crumble dried leaves before spreading them, because whole leaves mat into a soggy blanket that shuts air out of the soil.

Protecting evergreen plants

Evergreen plants are another matter altogether, because although slowed, their vegetation is not at a standstill during this period.

They still require care, especially as regards frost spells.

• As freezing creeps along a plant, the water portion of the plant’s sap starts to crystallize, which means the sap volume expands and bursts through the cells.

Luckily, it doesn’t take just a wee bit of freezing to actually kill the plant.
Often, only a very cold extended span of time is likely to endanger its survival.
But this also depends on the plant itself, which is why you should learn about how hardy they are.

Protecting plants that are directly in the ground

Use any simple plant-based mulch such as bark, flax mulch, a bedding of dried leaves, an inch or so (a couple centimeters) of compost or manure.

If you thus protect your perennial plants and your young shrubs, you’ll be keeping the roots free from frostbite.

• All the plant based mulches also make for great fertilizer.
• This protection will reduce the impact of freezing since the entire root system is covered and protected.

Shrubs can be wrapped in protective cloth called horticultural fleece which will protect their branches.

Protecting potted plants in their pots or garden boxes

They are the most vulnerable to freezing because the entire surface of the pot is exposed to cold air.

• It is important to place your potted plants in a place that is the least subject to cold and wind.
• One tip is to look for the corner where leaves tend to accumulate on your terrace, that generally happens when there isn’t enough wind to blow them away…

• Group pots together against a warm house wall; they shelter one another.
• Stand pots on bricks or pot feet so the drainage holes stay clear and the root ball never sits in water that later freezes.
• Terracotta and glazed pots crack when saturated compost freezes and expands, so keep them free-draining or move them under cover.

Protecting warm-weather plants against freezing

Certain types of palm trees, olive trees, citrus, oleander and other Mediterranean plants have grown more resistant to cold climates than in olden days.

Much progress has occurred because these plants are appealing, but some of it is also connected to global warming.

Tropical plants are now found in temperate climates, like palm trees and olive trees, where they previously couldn’t grow.

Take note though: horticultural fleece will only go so far, a few degrees at most. For instance, a lemon tree or an orange tree that would be hardy down to 19°F (-7°C) without fleece will now resist down to 14°F (-10°C).

• If your area is often subjected to winter freezing, it is strongly recommended to winterize your Mediterranean plants with horticultural fleece, especially if grown in pots.

Which plants need protecting, and how

Not every plant in the garden faces the same risk once temperatures drop. This table sums up how vulnerable each group is over winter and which measure the article recommends for it.

Whichever group your plant belongs to, mulch over the roots remains the cheapest and most reliable starting point.

Placing your plant correctly is important

Choose those settings that are most exposed to the sun and least exposed to wind.
If you can, bring your potted plants in a sheltered spot, cool and well ventilated over the winter.

Finally, just like all other plants, mulch is always recommended to protect roots when winters are cold.

Read more :

• Tips For Protecting Plants In Winter

• In the Northern Hemisphere a south-facing wall absorbs daytime sun and radiates it after dark, so pots set against the brickwork often stay warmer overnight than those standing in the open.
• Avoid hollows and the bottom of a slope, where cold air slides downhill and pools on still nights to form a frost pocket.

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