What Is A Hard Frost?
Hard frost occurs when the air temperature falls below 32 degrees Fahrenheit (0 Celsius). The lower the temperature, the faster it freezes. When the temperature drops to -10 or colder, frost begins forming on plant parts. The freezing point of water is 0 degrees Fahrenheit (-18 Celsius), but that’s not true for all substances. For example, ice crystals are found in some liquids at temperatures above -40 degrees Fahrenheit (minus 30 Celsius). At these extreme temperatures, the liquid becomes supercooled and solidifies into a crystal. Water is one such substance that forms ice crystals at extremely low temperatures. The reason why water freezes so slowly is because its molecular structure contains hydrogen atoms bonded together with oxygen atoms. These bonds create a barrier preventing the molecules from moving around too much. However, if the temperature is lowered enough, the bond breaks and water will begin to freeze.
The same thing happens with other substances like alcohol and acetone, which have similar structures. Alcohol and acetone form ice crystals at -20 degrees Fahrenheit (-4 Celsius) but they don’t become supercooled until temperatures drop below zero degrees Fahrenheit (-196 Celsius).
Hard frost is dangerous to plants because it dries out their cells and they eventually die as a result. However, some plants are able to survive these cold temperatures. Trees like pines and spruces have developed the ability to keep the water in their cells from freezing at extremely low temperatures. They also have a waxy layer on their leaves that protects them from drying out in sub-zero temperatures.
What Happens To A Plant During A Frost?
When a hard frost occurs, the water in the cells of plants freezes and expands inside its cells. In many cases, this expansion is strong enough to destroy the cell walls of the plant. The plant can no longer hold itself together and eventually dies when heat from the sun doesn’t thaw it out.
How To Protect Your Plant From A Frost?
If a frost is predicted in the coming days, there are several things you can do to protect your plants.
1. Move the plant inside to a room that stays warmer, such as a basement or garage.
Of course, only move hardy plants that can withstand indoor conditions. (These include pothos, spider plants, rubber plants, and aloe vera plants. )
2. Create a microclimate around the plant by grouping it with other plants.
The surrounding plants will protect the more sensitive plant in the middle.
3. Create a windbreak.
The windbreak will prevent cold air from reaching your plant.
4. Heating the soil might also help your plant survive frost, but this is not recommended for all plants.
(This will only work if you live in a place where the temperature doesn’t go below 0 degrees Celsius. )
5. Covering your plant with a blanket, tarp or sheet will protect it from frost, as long as it’s placed over the plant before the frost occurs.
You can also wrap the bottom part of the stem in plastic to prevent frost from reaching the plant. This method is especially useful when protecting young plants that have not developed thick stems.
6. The use of a frost blanket is also a useful way to protect your plant.
These are placed over the plant before the frost or ice hits it. The blanket is made from a porous material that allows the air to flow through, but not the cold. These can be purchased at most gardening stores.
7. A small fan can be used to protect your plant on a night when the temperature is going to drop below freezing.
Place the fan about a foot away from the plant. Turn it on low, and point it towards the plant. The fan will prevent the cold air from destroying your plant.
8. Slowing down the growth rate of the plant can make it more resistant to cold.
Many plant hormones speed up a plant’s growth, and these can be reduced or eliminated to make the plant less likely to suffer damage during cold nights.
9. Smear a layer of petroleum jelly on the leaves and the other above ground parts of the plant.
This will prevent the cold from killing it.
10. Wrap your plant in a blanket or place it in a cloth bag before the cold arrives. This method can be combined with smearing petroleum jelly on the leaves.
11. Use a plastic bottle to create a little greenhouse around your plant. Punch holes in the top for the air to flow through, and place it over the top of your plant before the cold sets in. You can fill it with hot water to speed up the warming process.
12. Create a little mound of earth or sand over your plant to shelter it from the cold. Make sure there are holes in the mound so that air can still flow in.
13. Create a heat trap by placing a pot with rocks at the bottom under your plant. The plants will absorb the heat from the rocks slowly over night, warming up the surrounding soil and protecting it from frost.
14. If none of these methods work for you, it may be that the cold is just too brutal for your plant. If this is the case, move to a warmer climate or choose another plant that can withstand the cold.
15. If you live somewhere that experiences snow, it is best to either remove the snow from your plant completely so that the soil is never covered, or to bring it inside until the snow melts. Snow acts as an insulator and will keep the temperature below freezing even on the warmest of days. (This is known as the “Snow Cover Effect”)
16. Slugs and snails love to feast on plants. You can prevent them from reaching your plants by placing small bits of metal, plastic or potsherds around the base. They are unable to crawl over these objects and will be deterred. If they still manage to reach the plant, you can catch them with a jar of alcohol or salt.
These two substances are toxic to slugs and snails, and they will die if they cross them.
17. Attract birds that eat insects and snails to your garden. They will keep your plants safe from pests and help them to grow.
18. Regular applications of fertilizer will encourage strong healthy growth. Make sure you read the instructions on the back before applying it, however, as too much can be as bad as too little.
19. When watering, avoid spraying the leaves. This will prevent the growth of fungus and mold that will decrease the plant’s chances of thriving.
20. Place a small drop of biodegradable soap in the watering can when watering. This will prevent fungus from growing on the water residue that is left on the stem and leaves.
21. Instead of using chemical pesticides, use garlic spray or salt water to get rid of pests such as aphids or whiteflies.
Sources & references used in this article:
The ecological and evolutionary significance of frost in the context of climate change by DW Inouye – Ecology letters, 2000 – Wiley Online Library
Hard frost, 1684 by A Snider – Journal for Early Modern Cultural Studies, 2008 – JSTOR
Frost hardiness in Scots pine (Pinus silvestris L.). by A Aronsson – 1980 – pub.epsilon.slu.se
Optima and limiting factors by FF Blackman – Annals of botany, 1905 – JSTOR