Protect Plants From Frost: A Guide For Savvy Gardeners

06/10/2021 Rob Walter

It's that time of year again: the weather is getting colder, and we're all beginning to think about how we protect plants from frost. Fail to do so, and you may end up with some very sad looking plants come springtime!

Horticultural garden fleece and plant jackets will most certainly keep your plants toasty this year, but there are plenty of other options to try too. Luckily, our gardening experts at William James have come together to share their top tricks and tips to protect plants from frost this winter. Are there any tips on this list that surprise you?

What Is Frost & How Is It Formed?

Frost is simply a deposit of white crystals on the ground or other surfaces, formed when water vapour in the air changes directly to ice. The freezing point of water varies depending on how much contamination there is but generally speaking water freezes at 0 Celsius.

The key thing about frost is that the colder it gets, the more damaging it can be. Plants will start to feel the impact of a freezing night and need protection; at lower temperatures, the damage increases exponentially.

It's essential to protect plants from frost in winter because the damage caused can be irreparable.

When Does Frost Occur In The UK?

Typically speaking, frost occurs between October and March in the UK. However, any time the temperature drops below freezing point, and there's a wind chill factor involved, you should protect your plants from frost.

The north of the UK tends to get colder weather than the South, which means gardeners in the North often have more of a job on their hands when it comes to protecting plants from frost!

What Causes A Cold Snap?

A cold snap is an abrupt drop in temperature which lasts for two or three days, typically between October and March. These occur due to large pockets of cool air moving across the UK from the north - these are known as a Polar vortex. In addition to this, cold air drifts over the UK at night from the North Sea and can cause a sudden drop in temperature.

How Does Frost Damage Plants?

Frost is a plant's worst enemy as it causes irreparable physical and chemical changes. Plants are made up of cells filled with watery sap that circulates nutrients around the plant. When these cells freeze, they can rupture and burst, causing permanent damage to your plants' cell walls.

This results in what's known as 'frost burn', which causes browned or blackened leaves on both evergreens and deciduous plants. Another obvious result of unprotected plants being exposed to freezing temperatures overnight will be dead or discoloured foliage, but that's not the end of the story. If left for too long, your plants could also suffer root damage or death, leading to further problems in the future.

Taking the time to protect plants from frost damage as part of your Winter gardening jobs will prevent these symptoms and ensure you have healthy flowerbeds come springtime!

How Should I Protect Plants From Frost?

Protecting plants from frost is one of the top jobs if you're gardening in October. There are many different ways to protect your garden plants from freezing temperatures over winter, depending on the type of plant you look after and how much damage your plants can sustain.

The first step is ensuring that the soil around any plant roots doesn't freeze - freezing soil creates expansive pockets of water, which drain energy and nutrients away from vulnerable root systems causing permanent damage.

This isn't usually a problem for plants in small pots, but for larger plants, you'll need to protect the soil from freezing by covering it with a thick layer of mulch - this will help insulate the root system and ground.

If you have a greenhouse or glasshouse, protect your plants from frost by making sure that at least ten centimetres of warm air above the plant. In an outdoor garden, this can be achieved using horticultural fleece or plastic sheeting - make sure to secure it properly with pegs and use enough layers so that no light penetrates through to the plant.

Where possible, protect your plants from frost at night by bringing them inside or covering any outdoor pots - even something as simple as a sheet of thick cardboard will protect the leaves overnight.

• If your garden is susceptible to heavy bouts of frost, protect against it by covering up vulnerable shrubs and trees with sheets or blankets overnight; this will prevent them from sustaining any severe damage. Do not wrap the sheet all the way around a tree or shrub, as it can cause damage to new growth that may have cracked.
• If your garden is particularly frost-prone, protect against heavy frosts by placing a thick layer of mulch over exposed roots and stems before covering them with straw, leaves or bark chips. Be sure to protect the mulch from being blown away by heavy winds, so secure it in place with stones or plant pots.
• If your house is particularly cold, protect against light frost on windowsills and other surfaces with sheets of plastic or even newspapers - this will prevent ice from forming between panes of glass. This will protect your plants from frost damage and prevent condensation in the winter, which can cause damp.

What Are The Most Common Plant Frost Protectors?

You have a few options if you want to protect your plants from frost, depending on the types of plants you grow and the type of garden you have. A balcony garden with potted plants needs a different approach to a low-lying vegetable garden where plants are grown directly in the ground. 

• For small plants or pots, protect against frost with a sheet of thick cardboard - you can also use old newspapers for this purpose. If using newspaper, make sure to protect it from the wind, so it doesn't get blown away and cover the plant in mulch before putting down your protectors.
• Heated water bottles - if you're on a budget, hot water bottles offer flexible protection for the whole night and can be moved around easily in small areas. They can protect plants from frost and cold snaps but need to be replaced every day/night.
• On the opposite end of the price range, water sheets can protect plants from as low as minus 23 degrees. They're easy and quick to install but also very heavy, so they need a lot of anchoring into place.
• Electric plant protectors - perfect for covering larger areas, electric protectors are a good option for covering many plants at once.
• The best way to protect plants from frost damage is by using plant frost jackets and horticultural fleece - these protect your garden from very low temperatures and are simple to use and easy to move around depending on where they need to be used.

What Plants Need Protection From Frost?

Certain plants need protection from frost more than others. For example, berry bushes and fruit trees need extra protection from winter weather that can cause damage to their blossoms.

You'll also want to protect delicate flowers such as Camellias, Cyclamen, Azaleas and Hellebores. Even a small amount of frost damage in the early months of spring can mean no blooms for your garden come summer.

Winter vegetables like potatoes, broad beans and carrots can be protected with fleece tunnels and horticultural garden fleece.

How Should I Protect Fruit Trees In Winter?

Fruit trees need extra care throughout winter to ensure they remain healthy during the colder months. This is particularly important for those who have recently planted their tree as it's still getting used to its new environment.

If your garden is particularly frost-prone, protect trees and plants against heavy frosts by placing a thick layer of mulch over exposed roots and stems before covering them with straw, leaves or bark chips. Be sure to protect the mulch from being blown away by heavy winds, so secure it in place with stones or plant pots.

What If My Garden Doesn't Experience Frost?

If you live in an area where it never gets cold enough to cause any damage to your plants, make sure they're protected during the winter months when heavy winds and rain can cause enough damage even without frost.

Perfect products for this include windbreak and shade netting. These are easy to install and provide an excellent level of protection from wind and rain. They can be used throughout the year but come into their own when the winter weather gets particularly nasty!

Summary: What Are The Top Tips To Protect Plants From Frost?

So, there you have it - our top tips to protect plants from frost this winter. Just before you go, here are some key takeaways that we've covered in this post!

• Protect vulnerable plant areas with thick layers of mulch. Be sure to protect your mulch from heavy winds by securing it in place with stones or garden fleece.
• Ensure that any protective measures you use, such as sheeting or fleece jackets, are anchored into the ground to protect against wind.
• Cover fruit trees with thick layers of mulch and protect the mulched areas from heavy winds by securing them in place.
• Bring vulnerable plants inside either in your shed, greenhouse or your windowsill.

When it comes to protecting your plants from frost, follow these simple steps for the best results!