It's the height of summer, temperatures are soaring and your lavender might be looking decidedly sorry for itself. Perhaps the foliage has lost its lustre or the flowers seem a touch droopy – so naturally, you reach for the watering can. It feels like the obvious fix. We're parched in the heat; surely plants are too? But according to the RHS, that's one instinct worth resisting.
Scorching weather doesn't automatically mean watering. During a heatwave, too much water can be a bigger threat than too little.
Lavender is built for Mediterranean conditions
Lavender hails from the Mediterranean, where it evolved to handle heat and drought. This is why the team at Kew Royal Botanical Gardens describe it as a good drought-tolerant plant for gardens.
The Kew team add that lavender naturally grows in "rocky soils, grassy meadows and on hills and cliffsides", where water drains away quickly rather than collecting around the roots. That's why established lavender copes better with dry heat than with constantly wet soil.
How to tell if your lavender actually needs watering
Don't water lavender just because the foliage looks tired. Instead, the RHS recommends checking a few centimetres below the surface with your finger. If the ground still feels moist, leave the plant alone – there's enough moisture around the roots. If it feels dry, give it a thorough soak so moisture reaches deeper into the ground, rather than watering little and often.
The RHS also advises against watering to a fixed schedule, as lavender's needs will vary depending on the weather and whether it's planted in the ground or a container.
Why overwatering can do more harm than the heat
It might seem logical to water lavender more often during a heatwave, but too much water is often the bigger threat. Lavender hates sitting in saturated soil – wet conditions starve roots of oxygen and trigger root rot. Frequent, light watering also backfires; deep watering is far more effective. According to the RHS, deep watering encourages roots to penetrate further into the soil, helping plants access moisture during prolonged dry spells.
The RHS recently urged gardeners to "bide their time" before automatically reaching for the watering can during prolonged dry weather, noting that soil beneath the surface often remains moist even when the top layer looks dry. When watering is needed, do it early in the morning and thoroughly, rather than little and often, and let the soil dry between. The charity also advises growing lavender in free-draining soil to prevent waterlogging and prioritising newly planted lavender over established shrubs, which are naturally drought tolerant once settled.
The exceptions to the rule
Established lavender planted in the ground is naturally drought tolerant and rarely needs watering, even during a heatwave. Newly planted lavender is different – the RHS notes that "deep watering encourages roots to penetrate further into the soil", so it will need more regular, thorough watering while it becomes established.
Lavender grown in pots is different again, as this soil dries out much faster than the ground, so it may need watering more often during prolonged hot spells. Whatever the type, always check before watering.
So if your lavender looks weary during a heatwave, feel beneath the surface before reaching for the can. A quick test can tell you far more than the weather forecast alone.
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