UK gardens expert guide to recovery after summer drought and heatwave

UK gardens took a battering this summer as a heat dome settled over western Europe, and much of the green and pleasant land turned a dusty beige.

Some areas went without rain for almost two months. The “joy of gardening” turned into waiting until the cooler evening period, then laboriously trailing out from the kitchen with buckets of water to keep the patio plants alive.

But as the rains begin to return, what can gardeners do to restore their garden’s lustre? And what have we learned as we look around our parched borders and fractured lawns?

Let’s start with the good news. Nature is resilient and many plants may still be alive despite appearing bedraggled, wilted or defoliated. They just implemented strategies that help them survive a drought.

Leaf wilting and abscission is the plant’s natural response to conserving water and protecting its vital phloem (which transports sugars from the leaves to the rest of the plant) and root tissues from desiccation.

So, gardeners don’t need to take the hacksaw to the shrub border yet with the notion of making a fresh start. They can check if individual woody plants are still alive by scraping off the epidermal cells (young bark) of the shoots with a thumbnail. If the phloem tissues below are green, life prevails.

Some of the garden’s woody plants may re-leaf again this autumn – or if they are herbaceous, throw up new shoots from the soil. But many will wait until next spring before investing in a new set of leaves or stems.

Gardeners should avoid the temptation to feed plants up (add fertiliser) now, as such chemicals placed on hard soils will simply wash away with the first rains, rather than be incorporated effectively into the soil. More than anything else, gardeners need patience at this time.

Some plants will have dead stems; these can be pruned out immediately. With perennial plants, though, it is worth hesitating before removing the whole specimen, as shoots can regenerate from the stem base or remaining root system.

Similarly, brown lawns will turn green again. However, if there are residual bare patches, new growth can be encouraged by sowing grass seed mixed in with sand in mid-to-late September.

Plants employ different strategies for survival based on the climate they evolved in, and we see a legacy of this in the cultivated species we use in the garden.

Those from high rainfall areas – such as certain rhododendron, pieris, hydrangea, magnolia and sorbus – struggled this summer. Hydrangea has limited capacity to control moisture loss, whereas more drought-adapted species such as cotinus can precisely regulate their stomatal pores (where CO₂ is absorbed and moisture vapour lost).

Other plants such as forsythia and fuchsia are chance takers, still trying to grow throughout a dry period by keeping their stomata open and just running the risk of water shortage. But these types of plants can come a cropper as water columns within their xylem vessels (which transport water and minerals from the roots to the rest of the plant) snap, causing the whole stem to fail.

Anecdotally, despite the harsh dry, hot conditions, some garden plants performed well this year. Salvia, verbena, lavander and, in my garden’s clay-based soils, roses flowered prolifically, even if their shoot growth was curtailed.

Rejuvenating your garden

For those gardeners keen to rejuvenate their dreary, desolate brown patches quickly, autumn bedding plants can help provide some late season cheer. Plants such as cyclamen, chrysanthemum, aster and winter pansies can be planted now as soil moisture is restored.

After a summer like this, some precious plant specimens will be lost, but many gardens should return to their former glories – if the UK experiences a cooler summer next year.

Over the longer term, as climate change moves the UK’s southern regions to something akin to a Mediterranean climate, some gardeners will need to adapt. Mainly, this will mean planting more Mediterranean flora.

Much more challenging, however, is the climate turbulence that accrues from climate change. This compounding of stresses – such as flooding in early summer followed by drought a few weeks later, not to mention more extreme events such as fire and high wind speed – is a much more difficult phenomenon for plants.

While research on this problem is still in its infancy, early results suggest that gardeners may need to look to plant species with multiple stress tolerances. Some garden plants that are popular in Britain, like buddleia, already have good resilience.

We can also look to new genotypes from the natural world. Plants from dry river beds, for example, cope well with both drought and flooding.

Plantlife with wide natural geographical distributions and weed-like strategies (where they grow and reproduce quickly) should also be brought into breeding programmes now, to help improve climate resilience in the garden plant palette.