You may have noticed at some point this summer, that some of your plants’ leaves have faded or shrivelled.
According to Guy Barter, RHS chief horticulturist, plants that have been scorched first appear “a bit grey, as the green is greyed over”.
He continues: “Then typically they start shedding the older leaves, or the older leaves start going yellow and then gradually the younger leaves can no longer be sustained and they go yellow too.
“At that stage, plants vary in whether they’ll come back or not. Some of them which have particularly strong roots which can hold a bit of moisture just enough to sustain life will come back.
“Others, with shallow, fibrous roots, are much less likely to survive.”
He adds that the situation of your plant can also lead to scorch, not just from the sun but also from the wind.
“If there’s a wind tunnel between two houses, for example, that will magnify the effect of the scorch because it’s like a hairdryer, sucking the moisture out of the foliage.”
open image in galleryThere are ways of seeing signs of life, says Kim Stoddart, editor of Amateur Gardening magazine and co-author of The Climate Change Garden with Sally Morgan.
“If the stems are flexible, that’s a telltale sign (that the plant is alive). Or run your nail down a stem to see if there’s any green.”
But she warns against moving a lot of the foliage because it can leave the plant more vulnerable, especially in another heatwave.
“That foliage can be providing protection for plants. Shade is absolutely key and the dead leaves can be providing a form of shade for other parts of that plant underneath,” she says.
But if your plants have been scorched and the leaves left crispy, don’t despair. Some of them will come back.
Survivors
1. Aubrieta
“Aubrieta is very resilient and has been a cottage garden favourite for centuries so it has an inherent ability to survive,” says Barter. “There’s an excellent chance of that coming back.”
open image in gallery2. Delphiniums
These beautiful tall plants with spires of flowers in a wealth of different colours have great fleshy root stock so are more likely to survive than other weaker-rooted cottage garden plants, says Barter.
3. Shrubs
Shrubs can start showing symptoms of wilting, but they are usually good at hanging on through dry periods, says Barter. It’s often a case of wait and see.
“All the common garden shrubs – philadelphus, weigela, deutzia – have evolved to grow in difficult places and are usually pretty good. They often have wilted leaves but they usually come back.
“I wouldn’t suggest whipping things out willy-nilly and I don’t think there’s a great deal to be gained from cutting them back,” he says. “Hang fire and hope some rain comes and restores them.”
“Some people say the plants are losing water and advise cutting back the foliage, but they need foliage to grow new roots to replace the ones that die back in the dry soil,” he adds.
4. Roses
Established roses will usually survive being scorched by UK summer heatwaves, despite presenting drooping stems, faded foliage and scorched petals as they are tough plants which enter a temporary survival mode by slowing down the production of new growth or flowers.
open image in gallerySo even if you see scorched leaves and very weakened stems, if the graft is still alive, the rose should survive. Water well late evening and lay a good layer of mulch – ideally compost or leaf mould – around the base of the plant.
Avoid removing scorched leaves until conditions improve, because these can still provide some shade to the base of the plant.
5. Crocosmia
While gardeners with fiery coloured crocosmia may have seen the sword-like leaves scorch easily, the RHS says that damage is likely to be superficial as they are tough, drought-tolerant plants which are likely to come back next year.
Strugglers
1. Hollyhocks
“Some cottage garden favourites like hollyhocks haven’t got much of a root so may well not survive and it’s the same to some extent with lupins,” says Barter.
2. Camellias
“Shrubs have different strategies depending on how they’ve evolved. Those which have evolved on the damp, soft forest floor, like camellias for example, are much less able to resist prolonged dry periods compared with those that have evolved on hillsides, like brooms,” says Barter.
3. Hydrangeas
Known to be thirsty plants, hydrangeas are also fibrous rooted and do not have much ability to withstand drying out, says Barter.
open image in gallery“Here at Wisley (RHS Garden Wisley in Surrey), we wouldn’t plant them on a south-facing slope because they would get baked. We might chance them on a north-facing slope where they’re out of the worst of the sun.”
The RHS is considering moving parts of its hydrangea collection from Wisley to its cooler northern gardens in Greater Manchester and North Yorkshire, due to increasingly hot and dry southern summers.
4. Small evergreen conifers in pots
So often we use little evergreen conifers such as Cupressus macrocarpa to add height to a container – but if you notice that their needles have gone brown through scorch or wind damage, you’re likely to have to start again, says Barter.
open image in gallery“They tend not to regrow from older wood. They haven’t got the resilience that shrubs have.”
5. Japanese maples
“They are famously vulnerable to drying out, so you need to plant them where the wind can’t get at them and make sure they’re in shade for part of the day,” he advises.
open image in galleryIf you’re worried the plant is suffering and can’t move it, put up some shade netting over some posts around the plant to keep some of the stress off it, he suggests.