What is overwintering? Meet the gardening technique that can save your flowers from frost

Everyone keeps talking about it, but what even is overwintering? Time to find out...

A greenhouse filled with geraniums for overwintering
(Image credit: Getty Images)

What is overwintering?

If you haven't heard the term before, you've likely asked the above at least once – but, we promise, overwintering is one of those garden ideas that every gardener, no matter their proficiency, needs to know about.

Thankfully, it's a pretty easy concept to wrap your head around. And, better still, once you know what you're doing, you can use all of your new overwintering skills to rescue your favourite flowers from frosts and cold snaps. Win!

What is overwintering?

The clue is in the name when it comes to overwintering, as it's all about helping your plants survive over winter.

'When cold weather arrives, we take measures to keep ourselves warm. We wear extra clothing, put on the heating or light a fire and, if it gets really cold, stay inside as much as possible,' explains Rob Grayson, head of plant distribution at Hillier

'We should take the same care of the plants in our gardens.'

A potted petunia plant on a table with candles

(Image credit: Future PLC/Lizzie Orme)

When it comes to protecting your plants to try and keep them alive through the winter, it's important to suss out their individual needs. 

Because, you guessed it, the phrase, 'What is overwintering?' will have a different answer depending on the plant in question.

'The specific methods for overwintering can vary depending on the type of plant and the weather,' says Morris Hankinson, director of Hopes Grove Nurseries. 'It may involve bringing plants indoors, insulating them, or providing them with extra protection against freezing temperatures, frost, snow, and ice.'

Morris Hankinson of Hopes Grove Nurseries
Morris Hankinson

Morris Hankinson is the founder and managing director of Hopes Grove Nurseries Ltd, the UK’s only specialist grower-retailer of hedging plants, which he established after graduating with a Commercial Horticulture Degree from Writtle College, Essex in 1992.

It is usually most common to overwinter tender perennials. However, if you've been trying to figure out how to overwinter lavender in pots, then you're still on the right track. 

Why? Because, while lavender is a hardier plant than most, plants in pots are always more vulnerable to winter chills than plants in the ground.

'Plants in pots are more at risk from the cold as the entire rootzone in the pot can freeze, especially in a cold snap after a wet period,' says Rob. 

Terrace detail with red Pelargonium on wooden tray table. New England Style renovation.

(Image credit: Future PLC/Polly Eltes Photography)

Still wondering what overwintering is? As mentioned already, it will look different depending on the plant you're trying to protect.

'The techniques for overwintering plants can include mulching, wrapping in hessian providing shelter, and controlling watering to prevent root damage caused by freezing and thawing,' says Morris.

Rob adds that herbaceous plants with tender bulbs or tubers, such as dahlias and canna lilies, can be 'dug up and overwintered stored in boxes of peat free compost in the garden shed'. 

'Don’t let them completely dry out,' he adds, 'but remember that keeping them too wet will lead to rot. A light water over the compost once a week should be plenty!'

Canna lilies

(Image credit: Getty Images/Jacky Parker Photography)

Of course, when it comes to plants like potted geraniums, the easiest way to overwinter them is to make like the Scandis and bring them inside for coddling during the colder months.

'A cloche or coldframe can also be useful for tender plants in your borders,' adds Rob.

Finally, we'd have failed to answer the big 'What is overwintering?' question if we didn't tell you when to begin the process. 

'To know when to start overwintering your plants, keep an eye on the weather forecast,' says Rob. 'Once overnight temperatures drop below 10-12°C, tender plants will need some protection.' 


What is plant overwintering?

'Overwintering involves protecting plants from the harsh conditions of winter to ensure their survival and health, particularly for plants that are not cold-hardy in a particular region,' says Morris from Hopes Grove Nurseries. 

'The specific methods can vary depending on the type of plant and the weather. It may involve bringing plants indoors, insulating them, or providing them with extra protection against freezing temperatures, frost, snow, and ice.'

It's common to overwinter with tender perennials, potted plants, or plants grown in containers that are susceptible to winter damage.

How do you overwinter a garden?

When it comes to overwintering your garden, it's a good idea to make sure all of your plants are pruned and ready for the cold snap ahead.

'Some of the plants in our gardens can be as vulnerable to the winter weather as we are. Each has its own degree of hardiness: the extent it will tolerate cold weather without damage,' says Rob from Hillier Nurseries. 

'Extremely hardy plants will endure temperatures well below freezing but more tender plants will need to be protected during periods of frost to avoid damage.'

Overwintering is all about giving plants extra protection from frosts and the cold. 'This could mean protecting tender plants such as ferns or palms with horticultural fleece (available on a roll, or in different-sized “jackets”) in situ, or could mean bringing some of your plants into a greenhouse or conservatory,' continues Rob. 

'A cloche or coldframe can also be useful for tender plants in your borders. Remember, though, that he soil temperature in your borders remains higher and roots can grow deeper than with potted plants, giving more protection from the ground frost.'

Rob adds that, while 'cold winds combined with frozen rootzones will cause foliage to go brown, crispy or even drop entirely,' many of your hardier plants should shoot back next spring 'so long as the core of the plant remains protected'.

Now that you've learned what overwintering is, it's time to start sussing out which of your favourite garden plants will need some TLC this winter.

And remember, bright sunny days often lead to cold nights without cloud cover, so be ready!

Kayleigh Dray
Acting Content Editor

Kayleigh Dray became Ideal Home’s Acting Content Editor in the spring of 2023, and is very excited to get to work. She joins the team after a decade-long career working as a journalist and editor across a number of leading lifestyle brands, both in-house and as a freelancer.