From washout to heatwave: keeping young willow stands alive
After record-breaking rain earlier in June, the British weather has flipped completely, and we now have an intense heatwave. The challenge for willow growers has shifted from managing floods to mitigating extreme heat stress. For mature willow stands, their deep root systems mean they can more easily handle a summer bake. But for young sets this transition from washout to heatwave is a high-stress event. Here is some boots-on-the-ground advice from the JSW team on how to help your young trees survive the heat.
The gold standard: survival over growth
First, a reality check from the fields: during a severe drought or prolonged heatwave, your goal is simply survival. Nothing beats decent, natural rainfall for driving growth. When a heatwave hits, you aren’t trying to force the tree to shoot up; you are simply keeping it alive until the weather breaks.
The watering trap: watch your roots
When growers see young trees looking stressed in the sun, the natural instinct is to water them. Be highly cautious with this approach. Frequent-but-light watering frequently moistens top couple of inches of soil. This inadvertently trains the willow’s roots to stay near the surface to find moisture. A shallow root system leaves a tree vulnerable to future droughts and wind damage. To build a resilient, premium tree, the roots need to push down into the water table where the long-term, permanent water supply lives. If you are going to water, it needs to be a heavy drench at dawn or dusk. You want water to sink into the earth, encouraging roots to chase it downward.
Worth considering: tree watering bags
For young stands in their critical first year or two, some growers have seen good results from tree watering bags (slow-release irrigation bags). These heavy-duty bags zip around the base of a young tree trunk and are filled with water. Instead of the water instantly running off the baked surface crust or evaporating in the hot sun, water is slowly released over a period of 5 to 9 hours, meaning it penetrates further into the subsoil, encouraging deeper root growth while keeping the tree stabilised through the worst of the heatwave. Naturally, deploying these bags across a large stand represents an extra upfront investment, but when balanced against keeping first-year trees alive through a brutal summer bake, it could be an investment that pays off. It’s essential these bags are removed when not needed to let the trunk breathe.
Keep the bases clear
The heavy spring rain means weeds are likely to explode in this heat. Unchecked weeds and high grass around the base of a young willow will steal moisture from the soil. Keeping 1-metre radius around the base of young trees clear of competing vegetation helps ensure every drop of water goes straight to the willow.
Ben’s Final Tip: Keep a close eye on your first-year sets over the next couple of weeks. Look for leaf-wilt or early yellowing. If they need a drink, remember to drench them deeply, or consider deploying watering bags to take the logistical headache out of the heat.