Their large flowerheads and handsome foliage make hydrangeas one of the most beloved shrubs for home gardens. All that beauty, however, can quickly turn into a sad sight when the hydrangea starts to wilt, which can happen for a variety of reasons. While wilting does not kill a hydrangea right away, it is the plant’s way of sounding an alarm that something isn’t right and you should take prompt action.
Here are some reasons for why your hydrangeas are wilting and how to fix them.
Lack of Water
It does not take a heat wave or drought for hydrangeas to wilt. Insufficient water is the most common cause for the leaves, flowers, and stems of hydrangeas to wilt. The name Hydrangea, stems from the Greek word “hydros” which means water. When its fibrous roots don’t find enough water to take up, the hydrangea loses its turgidity. The leaves start drooping and the stems aren't able to support the heavy flowerheads.
Hydrangeas should be planted in moist, rich soil. In soil that drains quickly, such as sandy soil, wilting occurs much faster than in soil rich in organic matter with better water-holding ability.
Shallow watering can also cause wilt. Rain showers and superficial watering with a can or garden hose aren’t enough to saturate the root zone. In the absence of precipitation, hydrangeas need to be watered deeply, ideally with drip watering. Slow watering is crucial, especially when the soil is dry, so the water can penetrate deeply. You can check the moisture level by poking a screwdriver into the soil.
Deep watering is the first aid and most important step to rescue your wilted hydrangea but there are other preventive measures to keep the plant less prone to wilting.
Add organic matter to the soil to improve moisture retention. You don't need to disturb the soil around an established plant, instead, add a little at a time to amend the soil gradually. Rake a 2-inch layer into the soil around the plant and repeat this once or twice during the growing season.
Annual mulching in the spring is equally important. This retains moisture in the soil during summer and has the added benefit of insulating the roots against winter chill. Apply 3 to 5 inches of mulch around the plant. Chunky mulch such as wood chips is ideal because wood is porous but you can also use chopped leaves or pine needles.
Hydrangeas can be grown in full sun but too much direct sunlight, especially during the afternoon hours when the sun is most intense, can cause wilt. When exposed to excessive sun, the plant’s internal temperature increases, which causes the leaves to transpire and leads to moisture loss in the cells. In this dehydrated state, the plant isn’t able to keep its flowers, leaves, and stems erect any longer so it starts to droop.
Watering the hydrangea promptly and deeply to make up for the moisture loss works as a short-term solution but if it is planted in a location where it gets too much sun, consider moving it to a spot with partial afternoon shade.
While some varieties such as panicle hydrangea are more tolerant of full sun than others, it is usually recommended to plant hydrangeas in partial shade, especially in hot climates.
Hot summer wind can also make a hydrangea wilt, as it accelerates the moisture loss caused by the sun.
In addition to watering, consider planting a natural windbreak that protects the hydrangea against damaging hot winds, or move it to a more sheltered location in your yard.
If you can rule out lack of water, sun exposure and wind as causes for wilting, you might be seeing the effect of fertilizer runoff from a nearby lawn, or you might have overfertilized the plant. Too much nitrogen causes rapid vegetative growth, but the leaves and stems are thin and spindly and droop easily. This often becomes more apparent during bloom when unhealthy stems cannot support the larger flower heads.
Excess nitrogen can also damage the roots and hinder the plant’s water absorption.
Keeping the hydrangea well-watered can dilute some of the excess nitrogen. There are also steps you can take to fix an over-fertilized lawn. Other than that, you just need to give the fertilizer time to wash out from the soil.
To prevent excess nitrogen, do a soil test before you add fertilizer to make sure you are not overfeeding the shrub. If it is indeed lacking nutrients, use a balanced slow-release fertilizer.
The best way to prevent fertilizer run-off from your lawn is to go easy on the fertilizer.
The hydrangea drooping after planting or transplanting is common. Even if you carefully dig out the entire root ball, damaging some of the fine roots is inevitable. Also, the plant needs time to adapt to the new soil conditions.
Water the hydrangea deeply once a day and continue the watering routine until wilting stops and the plant looks fully revived. Also mulch around the plant to preserve soil moisture. Otherwise, give it time to recover. By no means should you fertilize it, or prune any wilted plant parts. Both will do more damage to an already stressed plant.
Transplant shock can be prevented by planting in cool weather in the spring and fall, never in the summer, or in hot weather.