Ease the freeze: How to protect your trees from frost

Pine needles covered with frost

With temperatures dropping, and a touch of moisture in the air, frost is inevitable. While frost can completely destroy delicate plants, it also affects trees. Both young and mature trees are susceptible to frost. Don’t wait for the first frost to rush out and cover your trees with shade cloth! Follow our tips to prepare your trees for the cold weather.

 

How frost affects your trees

It’s not the frost itself that causes the damage, but the effect of the cold temperatures it generates on the internal structures of the tree. Ice crystals form within plant tissues and may even form inside the cells.

 

In response to the cold, some trees and plants thicken the liquid within their cell membranes—a form of natural anti-freeze. But the damage caused when ice crystals form inside cell membranes can destroy plant tissue, or cause the cells to lose moisture.

 

Pre-freeze tips and tricks

If you suspect that frost is in the forecast, take some preventative action by:

 

  • Moving potted trees to protected locations
  • Removing grass and weeds from around the base of the tree
  • Adding a layer of mulch (the right way)
  • Covering trees and shrubs that cannot be moved with sheets, tarp or shade cloth

 

As with mulching, there is a right way and a wrong way to wrap up a tree. The cloth should extend all the way down to the ground. But, it’s not necessary to create a seal around the tree. You don’t want to trap warm air around the tree.

 

And once again, if you do mulch your trees, don’t pile the mulch up against the trunk. This will prevent roots from getting the oxygen they need. The bare soil is also better at absorbing and reflecting the heat that will build up once the frost has melted.

 

Keep your trees well-watered

It might seem counter-intuitive, but keeping the soil moist around your trees will offset some of the damage caused by frost. This is because moist soil absorbs more radiation from the sun than dry soil. And it re-radiates the accumulated heat during the night creating a more even temperature around the tree.

 

Post-freeze recovery

Once the frosty season has ended, hold off on pruning your trees until the spring. You may realise that the damage is not as bad as you think and new growth can still spring from dead tissue.

 

If the dieback is severe and your tree has lost a substantial part of its canopy, use the cover to protect the exposed parts from the sun. Sun-scald often affects trees more in winter.

 

It happens when the sun heats up the bark to a point where cambial activity is stimulated. The cambium is a layer of dividing cells that are responsible for the secondary growth of roots and stems. When the sun disappears (blocked by a cloud or building), the temperature drops rapidly, killing the active tissue.

 

Winter is around the corner and it’s only going to get colder. If you’re pro-active about protecting your trees from frost now, they’ll be ready to face the winter and come out blooming.