I was the King’s gardener – how to help your garden survive in a heatwave

If the recent heatwaves in the UK have left your garden looking a little frazzled, you may be wondering what you should do to help your plants. There’s so much conflicting advice online about when to water and feed, and whether you should even bother mowing your lawn. But don’t worry, help is at hand. Jack Stooks worked at Highgrove House Gardens, in Gloucestershire, as a senior gardener for 21 years, where he expertly shaped the landscape under the King’s guidance. Originally from Zimbabwe, he arrived in the UK in 1998 to study horticulture, and he now enjoys helping private clients, giving online talks, and regularly providing royal and gardening commentary for television. He says one of the major issues in British gardens is the inconsistency of the weather. We may have one great summer, then the following year is a washout. While there are temporary heat spikes and heatwaves that can cause damage, the changeable weather makes it hard to plan for. “It’s not as simple as saying, ‘I’m going to plant for a hot garden or a rainy garden,’ because it’s impossible to predict what the weather will do,” he says. Shorts So, rather than redesigning your garden in anticipation of potential spikes in hot weather, it’s worth sticking with what works for your space and nurturing the plants you already have. Stooks knows a thing or two about keeping a garden lush in all weathers, and offers advice to help it thrive in the warm summer months. When it’s too hot, don’t feed your plants If you want lush flowering beds, Stooks says one thing you need to avoid doing during a heatwave is feeding them. It may sound counterintuitive, since you might assume thirsty plants would also need to be fed, but feeding encourages new growth, which can put extra stress on plants during periods of extreme heat. Feeding plants during a heatwave can also cause a type of burn, a chemical dehydration caused by excess salt or nitrogen in fertilisers, which draws moisture out of plant tissues and roots. Symptoms of fertiliser burn include yellow or brown scorched leaf tips, leaf drop, and striped or patchy patterns on lawns. How can you tell when it’s too hot to feed your plants? Stooks says, “Try digging around a border to check how dry the soil is. If there’s no moisture in the soil, that’s when you want to be making sure you’re not putting any feed in the ground. You can put down a really good heavy mulch over it, like a bark chip that is going to help the plants by holding moisture.” Mulch adds a layer of protection between the sun and the soil, preventing the soil from drying out too much. Water as early in the day as possible Stooks says the best time to water plants is early in the morning, between 5am and 9 am, when the outdoor temperature is cooler, as this reduces water loss to evaporation. Evening watering is acceptable, but damp leaves overnight can encourage pests and fungal diseases. The trick is to water less often but more thoroughly – then let the surface dry before you water again. “Even if you only have five minutes a day to tend to the garden, prioritise watering as early as you can, it can make a massive difference,” he says. When watering, priority should be given to young plants, hanging baskets and pots (which can’t draw moisture from the ground) and leafy vegetables such as lettuce and spinach. It may surprise you that garden favourites like roses don’t need much water; in fact, for two years Stooks had rose plants that thrived despite never being watered. Jack Stooks shaped the landscape of the Royal Estate under the King’s guidance for 21 years Let your lawn go brown It can be tempting to keep watering your lawn in a heatwave to stop it going brown, but Stooks advises against this, saying, “Watering lawns in this kind of heat is a waste of water and money. Lawns are really tough, and they will come back once rain comes.” If you want to keep mowing the grass, set the mower height as high as possible, as this promotes deeper root growth and builds resilience to summer heat. And if you’re tempted to rake up the grass cuttings, don’t, as Stooks says, “When you leave the grass to actually mulch into the soil, as it’ll help hold the moisture in.” Help feed your lawn with dry coffee grounds. “What I found is as long as you’ve got really dry granules and you’ve got really well rotted garden manure, you can mix that together, and spread it sparsely over the whole lawn, before any rain is due. The coffee grounds act like a slow-release fertiliser, which really helps the lawn flourish,” he said. If you’re going on holiday, try to get your pots in the shade In an ideal world, we’d get a friend or neighbour to water plants when we go on holiday, but that’s not always possible. Stooks says that in this scenario, when you go away, “put all of your pots into the shadiest, coolest area of the garden, to try and limit any damage from warm weather”. While he doesn’t like to use plastic in gardens, for environmental reasons, he says that “if you’re going away, you can buy big plastic trays that you can stand a lot of plants in. Make sure the plants are well watered before you leave, and then put water into the tray, so they are watered from the root up. This water will normally hold for quite a few days.” How to prepare for hosepipe bans As heatwaves become more frequent, so does the threat of hosepipe bans. Stooks suggests trying to stockpile rainwater as early as possible, with water butts around the garden: “If you have a garden tap, it’s quite easy to just turn it on and forget about how long you’ve been watering until you get your water bill! There’s also the environmental factor. We know we should all be conserving water, and when rainwater is free, and you can, you have the ability to put a water butt on your shed, on your greenhouse, on your own house, do it.” If you find water butts unsightly, you can box them in with some wood, hide them with planters or paint them to look more aesthetically pleasing. Don’t kill your plants with kindness It can be tempting to think more is better when it comes to watering your garden in hot weather, but Stooks says this could make plants less resilient and cause long-term damage: “If you mollycoddle plants by overwatering, the roots don’t have to do any work. Plants need to get a structure and support by rooting themselves, so that they can hold themselves up. Their roots need to be able to seek moisture when it needs it, not rely on human intervention all the time. I’m not saying don’t ever water, of course not. But make sure the ground is properly dry before adding any more water.” Jack Stooks is working on behalf of Coffee Friend, an international online retailer that specialises in coffee machines, beans, and coffee-making accessories.