Hortnews 2021 Special Article on Protecting Plants from Cold;

KSRE - Horticulture


There has been a number of questions on what we should do to protect our plants from the cold snap forecast for tonight.

Protecting From Spring Freezes

· Water the soil thoroughly if you did not get snow and the soil is dry – wet soils hold heat better than dry soils.

· Move containers or unplanted plants indoors or in an attached garage

· Use blankets or sheets to protect plants. Do not use plastic sheeting. The goal is more to trap ground heat than prevent cold from getting in. Therefore the covering much reach the ground. You may have to weigh down the covering if wind is forecast. ·

· Do not uncover the plants tomorrow until the temperature rises above freezing.

Recommendations for Specific Plants

Trees: Should be fine.

Shrubs: Should be fine.

Perennial Flowers – should be fine.

Plants that likely won’t make it.
Tomatoes and Peppers
Plants that need to be covered
Potatoes, radishes, spinach, leaf lettuce, beets, mustard
Plants that should be fine,
Onions, cabbage, broccoli, cauliflower, carrots, turnips, kale

Special Cases include potatoes, asparagus and rhubarb.
Potatoes will send up new growth from dormant eyes if the top growth was killed.
Both asparagus and rhubarb will also send up new growth if top growth was killed.

Fruits: Plants will be fine but it is the fruit we are worried about.

So how sensitive are fruit tree flowers to cold.? As a rule, a temperature of 28 degrees will kill 10% of the fruit buds but a temperature 25 degrees will kill 90%.

Strawberries – cover if they are in bloom.

Peaches and apricots – Peach fruit buds were likely killed by the extreme cold in February. Any fruit that did set will likely be killed by the cold this week.

Apples and pears: Will likely thin the crop but not eliminate it. This may actually be good for them as too many fruit reduces quality.
Want an apple and pear every 4 to 6 inches.

Sand plums and American Plums: Likely no fruit this year if we hit 25 degrees.

Thornless Blackberries: February cold snap likely killed the fruiting canes to the ground but new canes will come up.

Raspberries and thorny blackberries: Probably OK.


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