Hydrangeas wilting in July heat? Add this natural layer to the soil now for better blooms next summer - Netmums
July often brings the hottest, driest spell of the year just as hydrangeas are smothered in blooms. Those big, billowy heads can hide the fact that the shrubs are already under stress and may flower badly. . .
July often brings the hottest, driest spell of the year just as hydrangeas are smothered in blooms. Those big, billowy heads can hide the fact that the shrubs are already under stress and may flower badly next summer if nothing changes. Garden specialists say that adding one simple natural material to the soil in July can tip the balance. Used properly, organic mulch protects roots in hot weather and helps hydrangeas keep blooming strongly. Why hydrangeas struggle in July heatJuly is typically one of the driest months in the UK, and hydrangeas have very shallow roots that cannot hold much moisture, so they start to suffer even when they are watered regularly. Fast transpiration through the leaves in hot sun means they lose water faster than they can take it up. When you see leaves curling, turning brown or going crispy, heat damage has already set in and buds can be hit too. Hydrangeas that go through prolonged heat stress often produce fewer flowers the following year, and old-wood varieties may fail to bloom at all because their flower buds were damaged. Specialists at Gardening Know How warn what happens when soil is left bare. They explain: "Bare, dark soil around your hydrangeas acts like a heat sink. The soil absorbs a lot of the heat from the sun, cooking delicate roots underground and causing moisture to evaporate quickly. "The same experts add: "Hydrangeas tend to suffer from this heat and dryness in the summer, so take steps to reduce the effect. " Their key recommendation is clear: "The best thing you can do is mulch generously around each shrub. Two to three inches of mulch does several things to support healthy plants: it regulates the soil temperature, keeps it cooler, holds moisture, and suppresses weeds. All essential for growing those stunning, billowy hydrangea blooms. "The natural mulch that helps hydrangeas bloom betterThe “natural item” they are talking about is organic mulch, such as wood chips, bark or straw, spread in a ring around each shrub. On hot days this layer shades the soil, slows evaporation and stops delicate surface roots being baked. Because the mulch keeps the root zone cooler and more evenly moist, the plant experiences less stress. Less stress now means more energy available to set and protect flower buds, so you see better blooming both this season and the next. In summer, coarse wood chips and straw work well because they hold plenty of moisture while still letting air reach the soil. Experts advise piling mulch up to about 5 to 7 cm deep, then keeping a small gap around the stems so that the base of the plant stays dry and less attractive to pests. Mulch is not a substitute for water, though. Deep watering once or twice a week remains vital, and the mulch simply helps the soil hang on to that moisture instead of letting it vanish in a day of scorching sun. Coffee grounds, colour tricks and how not to overdo itMany gardeners also experiment with coffee grounds around hydrangeas, mainly to tweak flower colour rather than to manage heat. The site Planting Tree notes: "Some people say they manage to change the colour of their hydrangeas with coffee grounds. In theory, coffee grounds contain enough acid to increase the acidity of the soil and turn hydrangeas into blue hydrangeas. "Planting Tree stays realistic about how reliable that is: "This method can work, and coffee grounds break down well in the soil, so there is no downside to trying it. But if you want to increase your chances of results, you might consider a product specially designed to boost the acidic balance of your soil. "For composting, Gardener’s World highlights the structure of used coffee as a bonus, saying: "The small, damp particles of coffee grounds are an excellent compost ingredient to speed up the process". The magazine also reminds readers that "Coffee grounds tend to be slightly acidic and are therefore well suited to ericaceous plants such as hydrangeas, but to be used only in moderation on a single plant. "Some horticulturists even describe the way coffee can nudge pink blossoms towards blue as "plant alchemy". Gardener’s World adds a broader warning here too: "coffee tends to be slightly acidic and therefore suits acid-loving plants such as hydrangeas, as well as nutrient-hungry plants such as roses, but again, do not use it more than in moderation on a single plant. "