It’s not just people who feel the adverse effects of heatwaves; our gardens do too.
High temperatures and dry conditions can put gardens under significant stress, causing lawns to brown, flowers to wilt and vegetables to struggle.
But whilst we can’t control the weather, we can prepare our gardens for what’s now become an annual occurrence in the UK.
David Denyer, our resident flower expert, has some simple steps you can take to help your garden withstand the next heatwave.
It feels like watering more often during a heatwave would make sense, but this is one of the biggest mistakes you can make. Shallow watering encourages roots to stay close to the soil's surface, where temperatures are highest and moisture disappears quickly.
The answer is to deep soak. This allows water to penetrate further into the ground, helping plants to develop stronger, deeper root systems that are better equipped to find moisture during dry periods.
This approach not only helps plants become more resilient, but also makes better use of water by ensuring it reaches the roots where it's needed most.
Some ways in which you can deep soak your plants are as follows:
- The Trickle Method: Place a garden hose at the base of your plant and turn the water on to a gentle trickle. Leave to run for 5 -10 minutes, then move it around the plant's drip line, this will ensure moisture penetrates deep into the soil where roots need it most.
- Drip Irrigation: A drip irrigation kit is a great way to deliver water slowly and directly to the soil around your plants. Running the system for one to two hours will allow water to soak down to the root.
- The Cycle-and-Soak Method: For this method to be effective, apply water for around five minutes, break for 30 minutes to give the soil time to absorb the moisture, then repeat, twice if necessary.
Choosing the right time of day to water is just as important as how much. You'll want to do it at the coolest times of day, either early in the morning or in the evening.
If you water at the hottest and sunniest times of the day, it will lead to a significant amount of water being lost through evaporation, meaning plants won’t have a chance to absorb it. Watering in full sun can also leave droplets sitting on leaves, which isn't ideal during periods of intense heat.
Applying a layer of mulch (bark chippings, compost, well-rotted manure or leaf mould) around 5-8cm thick around borders, shrubs and vegetable plants will give you many benefits. It will help retain moisture, suppress weeds that compete for water, help regulate soil temperature and improve soil structure as organic mulch breaks down over time.
Container plants can suffer during hot spells, as they are prone to drying out and can become waterlogged after sudden summer downpours.
Containers need adequate drainage holes for excess water to escape, preventing roots from sitting in saturated compost, which can lead to root rot and other problems.
If you have decorative pots without drainage, consider placing nursery pots inside them so excess water can be emptied after rainfall.
To help your container plants look their best during those really hot periods use larger pots that retain moisture for longer, add water-retaining compost where appropriate, raise your pots slightly on feet to improve drainage and move any vulnerable containers into partial shade during the hottest part of the day.
For both efficiency and effectiveness, group plants with similar watering needs together. This will also make sure you don’t overwater drought-tolerant species or underwater thirstier varieties.
As an example, you could group Mediterranean plants such as lavender, rosemary and olive trees together as they prefer much drier conditions than hydrangeas, hostas or many vegetables.
With clever grouping irrigation becomes simpler, you’ll save water and reduce maintenance throughout the summer.
Some plants and flowers (young plants, newly planted shrubs, delicate flowers etc) will need temporary protection during periods of extreme heat. You can provide this with a garden fleece, shade netting or even strategically positioned umbrellas. Anything that can help reduce direct afternoon sun without blocking all available light.
It’s not a bad idea to also move container plants into sheltered areas during the hottest part of the day before returning to their usual position once temperatures cool.
Avoid excessive feeding during very hot weather as this can encourage soft new growth that's more vulnerable to heat stress.
Pay close attention to individual plants' feeding needs and stick to that for best results. Well-watered, healthy plants are far better equipped to cope with high temperatures than those pushed into rapid growth.
The best defence against a heat wave starts before temperatures begin climbing. Checking irrigation systems, topping up mulch, weeding borders and ensuring containers drain freely all make a significant difference once hot weather arrives.
By making sure everything is in place before a heatwave hits will give your garden the best chance of survival during the hottest days.
Water efficiently, conserving moisture and giving plants the conditions they need to develop strong root systems and your garden will thrive throughout the season.