Tender plants

A cold snap can wreak havoc in the garden if you don't protect frost-tender and borderline-hardy plants. Alan Titchmarsh explains how to do it

- Alan Titchmarsh

The nationwide cold snap in December 2022 reminded us that a lot of plants we'd come to regard as hardy were, in reality, not quite as tough as we thought. For a good decade and more we'd brought the likes of penstemons and shrubby salvias through winter out in the garden without a problem, but many gardeners lost the lot last winter.

Global warming isn't a figment of our imagination, but it's a mistake to forget that thing called 'weather' - even with overall rising temperatures, there'll always be cold snaps that catch us out and remind us that when we grow plants from all over the world, sudden drops in temperature can take them - and us - by surprise.

I can still recall a 20-year experiment to verify the hardiness of eucalyptus species in the UK. It found that if temperatures dropped gradually, the plants could survive a surprisingly cold winter. However, a sudden drop - even if it wasn't nearly as cold as a steadier decline - resulted in sudden death.

With tender bedding plants, we ease them into cooler temperatures by 'hardening them off' - gradually accustoming them to lower temperatures in the weeks prior to planting out at the end of May. It's worth remembering that plants are just as sensitive to sudden drops in temperature as we are, except that they can't simply reach for a vest or a sweater.

What does 'tender' mean?