The time is soon approaching for frost. Some fruit trees can withstand more frost than others.
However, all plants must be protected against potential frost damage so that they can make it through the winter and live on until next year.
The varying stages of bud development on a fruit tree can tolerate different amounts of cold.
However, the buds that appear early on a fruit tree like an apple- or other fruit trees will be able to tolerate tissue temperatures between 15 to 18 degrees F. It’s common that up to 10 percent of them will suffer damage.
When buds expand and become flowers or young green fruits the tolerance will drop considerably.
A fruit that can’t tolerate low temperatures is citrus fruits, where protection measures should begin anytime when the air temperature drop below freezing is expected.
Why do farmers spray water on fruit trees before a frost?
When the air temperature drops below freezing, farmers tend to spray their fruit trees, especially citrus to keep them wet with water near 0 °C.
The cold water will effectively provide heat to the fruit trees. The cells in water freeze at a little below 0 °C, but if you can water your fruit tree with water at 0 °C, you will see the heat released as ice forms on the fruit and prevents damage.
The reason for this is there will be no temperature changes because the water freezes at 0 °C.
Therefore the heat released is called latent heat. The latent heat is “hidden” heat or heat which can’t be seen with the naked eye.
What damage can frost do to your fruit trees?
Cold damage on fruit trees occurs when fruit crops are exposed to low temperatures and the lower the temperature, the more damage can occur.
The damage from freezes on your fruit trees depends on the development stage of the fruit crop.
Frost damage may have an effect on the entire tree or affect only a small part of the tree, which may reduce the overall product quality and the total amount of fruit produced from the tree. A lighter frost may not cause as much damage because it is usually short-lived.
Damage can occur indirectly on a fruit tree’s buds when ice forms inside the bud, but outside the cells or directly when the ice crystals form inside the cells.
Depending on how quickly the temperature drops, the higher can the damage be due to freezing inside the cells and to which level it cools before it is frozen.
However, when there is ice on the outside of leaves on a fruit tree at temperatures from 0°C to -2°C, they will become dry and brittle and can often be as sharp as a knife.
When the temperatures are below -2°C freezing damage occurs. At this low temperature, the cell walls and membrane rupture due to the crystals formed inside the plant tissue.
How does frost occur?
When water vapor reaches the freezing point in the atmosphere it will change to a solid forming a thin layer known as “frost”.
Frost will look like small white crystals when it appears on the ground. Frost may coat objects because they can become colder than the surrounding air.
Frost will always occur more frequently in low-lying areas because the warm air rises, while the cool air contains more water molecules and goes down.
The cool air collects and descends to the ground and frost forms. This will usually happen overnight when the air temperature is cooler. The frost will melt faster in the morning the following day when the sun’s rays hit the ground and the air temperature begins to rise.
It is essential for farmers to know if there will be frost in a given area when they have to choose which crops to grow in a specific agricultural area.
Frost and many other factors are important factors that can determine whether it will be a good or bad harvest.
Frost can help damage farmers’ crops and definitely destroy plants or even fruits.
It can be seen that farmers can have whole fields of crops destroyed by a few frosty nights and it is therefore important that the right crops are chosen for the right agricultural areas.
Should I water fruit trees before a frost?
The cold winter air is normally dry and the wind can remove water from plants faster than the roots have the opportunity to absorb the water.
If you expect freezing weather be sure to water the entire root system. A great rule of thumb is to try water early in the day, so the plants have time to absorb the water before the temperature drops at night.
However, if the ground freezes due to the low temperature, the underground water will turn into ice crystals and these will not be able to be absorbed by the plant roots.
Remember that even dormant trees or plants need to absorb water year-round to not die or dry out completely.
Plant cells which contain more water, will be stronger against cold damage and freeze because water acts as an insulator. Likewise, moist soil will be able to stay warmer than dry soil.
Therefore, it is recommended to have a regular watering schedule, which can help protect plants and trees from freezing temperatures.
If you live in an area where your soil stays frozen all winter, the fall is the best season. Try to make sure that everything is watered well before the ground freezes.
Try to be extra attentive to newly planted shrubs, trees, and plants. Their roots will be less established in the ground, which can cause the soil to open up more, and colder air can thus penetrate deeper down to the roots.
You can still water your shrubs, trees, and plants when the air temperature is above 40° F, but don’t water if the temperature is lower and if there may be snow or ice on the ground.
When you using water and the temperature is that low, it’s important to not overwater your shrubs, trees, and plants.
If you water once or twice per month it should be enough because the plants will not be able to absorb the water as fast as in the growing season.
Can I put warm water on frozen plants?
No, you should definitely not put warm or hot water on your frozen plants. The high difference in temperature can destroy the plant cells and by that do even more damage than the frost itself.
It’s way better to let frost melt itself naturally. However, it is possible to use warm water to defrost frozen soil, if the air temperature is at least 59 °F and the frozen soil is under a thick layer of mulch or other forms of soil.
This can often be done in the spring when there is no longer night frost, but instead a milder temperature.
Final thoughts
The buds on fruit trees can tolerate temperatures between 15 to 18 degrees F.
However, it’s possible to protect fruit trees from frost with water, because it keeps the fruit trees wet when the temperature falls to 0 °C
The water will provide heat to your fruit trees when the cells in the water start heating if you water your fruit trees at 0 °C since there will be no temperature changes because water freezes at 0 °C.
The frost damage may have an effect on the entire fruit tree, but it can also only be a small part of the tree. However, it can affect the production of the total amount of fruits.
Lastly, even though you think it may be a great idea to try to use warm water on your frozen plants – then it is definitely not recommended. Instead, let the frost melt naturally.