If you’re a bit confused about protecting plants from frost and cold weather, you’re not alone!
Which plants to protect from cold weather, what temperatures cause damage, and what to use to protect your plants are all things you need to know if you want to avoid losing your precious plants. These tips on how to protect plants in winter will help you take care of your tender plants, so that you can enjoy them again next year.
When to protect plants from frost
It’s so tempting to leave your tender plants unprotected when the weather is still mild, but temperatures can drop quite suddenly in the garden from autumn onwards. This is the classic time when we get caught out.
Pay attention to the weather forecast – particularly overnight forecasts – and take action if it looks like a cold spell is on the way.
Bear in mind also that drier conditions pose a higher risk of frost damage. Dry air causes moisture to evaporate from soil, making it colder.
Finally, don’t assume that the risk of frost disappears once winter is over. A spring frost can cause just as much damage to your sensitive plants.
Will one night of frost kill my plants?
If your plants are tender, a single night of frost has the potential to kill them. This is why it’s so easy to get caught out!
If you understand which plants need protection in winter, you’re well on the way to avoiding frost damage.
Which plants need protection from frost?
Which plants need frost protection depends on a number of factors.
The first is the location of your garden. If your outdoor space is quite sheltered, you may find that some tender plants survive perfectly well, but this wouldn’t be the case in a more exposed area.
Equally important is the variety of plant, and whether it is classified as ‘hardy’, or ‘tender’.
Hardy plants can generally cope with a short spell of freezing temperatures. Do bear in mind though that a hard freeze of -2°C or lower has the potential to destroy most plants. Popular cold hardy plants include clematis, honeysuckle, heuchera, euphorbia, hydrangeas, buddleja, rhododendrons and some rose varieties.
Tender plants (also sometimes called semi-hardy or half-hardy plants) are usually unable to survive hard frost, and need to be protected or brought indoors over winter. Popular tender plants include fuschia, dahlias, pelargoniums, tree ferns, canna lilies, begonias and some succulents.
If you’re not sure whether a plant is hardy or tender, the care label that came with it or a quick online search will help you work it out. If you don’t know the variety of your plant, there are some great plant identification apps available, or you could think back to last winter – did the plant survive frosts then? With this last option, do bear in mind that some winters are harsher than others, and a plant that survived last year could still struggle this year. I think it’s always best to err on the side of caution, and protect your plants if you’re not sure.
Finally, new growth on plants, and plants that aren’t well-established are particularly vulnerable to frost damage. Take extra care with these.
At what temperature should you cover plants?
Frost occurs in temperatures below 0°C (32°F), so this is the tipping point beyond which you need to protect plants in winter. Hardy plants should be able to cope with light frost and cold air, but as I’ve already mentioned, temperatures of -2°C or lower are a danger zone for most plants.
How to spot frost damage in plants
There are a number of signs that your plant has been damaged by frost.
Frost can make leaves look scorched, brown, spotted or saturated with water. It can also damage petals, and cause stems to blacken or collapse. A repeated cycle of freezing and thawing is particularly damaging.
Freezing temperatures also cause problems that originate below the ground, because frozen soil prevents a plant’s roots from absorbing moisture.
Frosts in springtime can cause damage to new growth on a plant. This usually happens around the more exposed parts of the plant, and looks like scorching or brown patches on the leaves.
How to protect plants in winter
So you’ve worked out which plants you need to protect from frost and cold winter weather. Now let’s take a look at the different types of plant protection you can use.
Moving your plants indoors
Moving your plants to a more sheltered location is the simplest way of protecting plants from frost. It doesn’t involve buying anything either, so it’s a great thrifty option.
Completely tender plants such as cacti and some succulents will be happy to move indoors. Ideally you should position them on a windowsill to make sure they get enough light over winter.
Tender garden plants in containers should be moved to a location that’s cool and frost-free. A porch or unheated conservatory is perfect, but if you have a greenhouse or cold frame that remains frost-free in winter that’s a good option too.
If you have frost tender plants that are in the ground, you might want to consider lifting them and putting them into a container, so you can move them for the winter months. Obviously this isn’t a great option for large or well-established plants!
How to protect potted plants from frost
You can give container plants an extra layer by wrapping the pots in bubble wrap, this is a great diy frost protection for plants. The bubble wrap will help to prevent the soil freezing and expanding, which can damage roots and crack terracotta pots. You should also aim to raise pots off the ground using *pot feet, to stop them sitting in an icy puddle all winter.
Protecting plants from frost using fleece
*Horticultural fleece is great for protecting plants from frost; you simply place it over plants – a bit like wrapping the plant up – and secure with string. You can also use straw, *hessian and bracken. The RHS has a good guide to wrapping plants here.
Using mulch to protect plants
Adding mulch around the base of your plants provides them with an insulating layer of organic material. This can help to prevent the ground freezing and causing root damage. Compost, bark chippings, manure and leaf mould are all great options for mulch.
Using cloches to protect plants
A *cloche is a clear cover that can be placed over a plant to protect it from the cold. Cloches are usually made of glass or plastic, and are available in sizes to suit individual plants right up to rows of vegetables. Cloches should be removed during the day when the risk of frost has passed to allow for ventilation and access to moisture.
You can improvise a cloche from an upturned flower pot, a glass jar, or even a milk or juice bottle with the bottom removed.
Leaving old growth on plants
This is another easy way of protecting plants from frost. The previous season’s growth can provide protection for the plant, so it’s a good idea to leave it rather than cutting it back.
How to save plants from frost damage
Despite your best efforts, you may still have to deal with frost damage on your plants. If this happens, the best thing you can do is remove the damaged parts of the plant, cutting back to a side shoot or bud that remains undamaged. It’s also a good idea to apply a general purpose *plant feed to help the plant recover.
Don’t be too hasty to remove and dispose of plants that have been hit by frost. There’s still a chance that the roots are intact and new growth will prevail.
An insurance policy against frost damage
No matter how careful you are with protecting your plants, there will still be a risk of losing some of them. For this reason, it’s a great idea to take cuttings from your plants in autumn; doing so will hopefully provide you with backup plants next year. And if you end up not needing them, you’ve got yourself some extra plants for free – what’s not to love?!
More gardening inspiration
For more winter gardening ideas, you might to take a look at these posts: