During Extreme or Unseasonably Cold Weather, There Are Some Ways to Protect Your Trees/Shrubs:

How to protect citrus trees from frost

Citrus trees are certainly the most fragile of the bunch. Most citrus trees need to be taken into a greenhouse or your home during the colder months here. Yuzu is pretty cold hardy and is the only citrus tree I know of that can be planted outside in this region. With that being said, if you have any cold hardy citrus in the ground: to protect your smaller citrus, put stakes in the ground around the tree and drape it with a fruit tree frost blanket, sheet, burlap, or other cloth during the day before the freeze. Make sure the cover goes all the way to the ground. A cover is used to hold/build heat around the tree. It is also important to keep mulch from around right around the trunk of the tree. This will allow the soil to absorb some heat.

How to protect peach trees from frost:

You can also use a sheet or blanket on your peach trees. Just like with citrus, cover during the day so heat can build up before a nighttime freeze. 

How to protect apple trees from frost

Apple trees handle the cold quite well. If you have a few younger apple trees, it would be nice to cover them just to be safe.

Fruits Adapted to Freezing Temperatures

Some fruits are less likely to be affected by late frosts by virtue of being later producing fruits, or late-blooming varieties. Raspberries and blackberries for instance tend to flower after the risk of frost is past, as do pie cherries and most blueberries. If you live in a frost-prone environment, choosing late-blooming fruit is a safe option to avoid frost damage.

Several types of fruit trees are acclimatized to local weather conditions and can survive freezing temperatures. A properly cared for apple or pear tree thrives in a cold climate, and plum trees are one of the best fruit trees to grow in a colder region.

Citrus and peach trees are not very cold hardy and tend to need protection from freezing temperatures. Young trees are also more likely to suffer damage to their tender wood and should be protected accordingly. 

Winter Pruning

It is important not to prune your fruit trees during freezing temperatures. Pruning while daytime temperatures are above freezing is okay even if the night dips into freezing temperatures. Pruning while temperatures are freezing can cause the branch to crack more than cut due to the water within the tree being frozen. This could cause more harm than good.

Protecting Fruit Blossoms from Frost

While we are still in the height of dormancy here in the Portland area, and the cold temperatures forecasts for this weekend don’t have me too worried, this seems like a good occasion to consider the risks associated with freezing temps in the spring. Late frosts do the most damage to fruit trees and plants because the buds are coming out of dormancy and exposed to weather they aren’t equipped to handle in their current state. Here in the Pacific Northwest, we do not experience the extreme temperature dips that are seen in other fruit-growing regions such as the east side of the mountains or the Midwest. That said, the temperate nature of our growing zone often means trees will bud out early in response to a warm spell, only to be struck with a quick freeze that can ruin the coming year’s fruit. Frosted blossoms can result in little or no fruit, so it pays to take action to protect your lovingly grown fruit trees and bushes from a late-winter cold snap.

Check your plants when temperatures start to drop below 32F, and if they are showing no opening of flower buds, the flowers will survive and produce. If you do see signs of bud-break, this is the time to take action.

Covering Blossoms to Protect Against Frost

When it comes to smaller fruits and dwarf trees, you may be able to cover the entire plant. For bushing fruit such as currants or gooseberry, consider using tunnel cloches or individual cloches. The best materials to use for a tree wrap are burlap or cotton. They prevent the cold air from coming into contact with the leaves and allow the moisture on the leaves to escape. An old comforter is effective, but bedsheets do not provide enough insulation to keep the plant from freezing. Plastic is not advised, but if you do use it, don’t let it touch the leaves themselves, creating a tent-like cover with stakes or rope. Stakes can puncture the material, so place something over the end – old tennis balls work well. Make sure it extends to ground level to trap warmer air next to the tree. Don’t forget to remove covers during the day to let insects in to pollinate the flowers!

Clearly, large trees cannot be covered up entirely, however, flowers higher up on the tree may remain warm enough and go on to produce fruits even if the blooms on the lower branches get zapped. Cover those branches that are accessible, ensuring at least the lower fruit is protected.

We hope this was helpful and potentially saves some of your fruit if it comes to that!

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