How Often to Water Hydrangeas for the Biggest, Boldest Blooms

Hydrangeas are one of the most popular plants in the garden thanks to their large, showy blooms. To ensure their impressive flowers stay healthy all season long, proper watering is essential. Too much water and you risk welcoming pests and diseases, but too little and the flowers may dry out. To ensure you give your hydrangeas the perfect amount of water, we spoke with gardening experts who break down the factors to consider when watering these popular plants.

How Often to Water Hydrangeas

In general, hydrangeas need about 1 inch of water weekly. That said, newly planted hydrangeas will need more water than established ones. "For newly planted hydrangeas, frequent and thorough watering is crucial to encourage deep root growth," says Gail Pabst, gardener and marketing director at the National Garden Bureau. Aim to water young hydrangeas approximately once every other day and established hydrangeas once a week.

To determine if your hydrangeas need a drink, stick a finger in the soil and water when the top inch feels dry or if the leaves look wilted in the early morning or late afternoon. "Note that wilting in the intense afternoon sun may not indicate a need for water, as leaves can perk up once the sun passes," Pabst says.

Factors to Consider 

Besides age, there are other factors to consider when watering hydrangeas, such as soil type, sun exposure, temperature, and more.

Soil

Hydrangeas like moist (not soggy) soil that is well-draining. The type of soil you have will determine how often hydrangeas need water. For example, clay-based soils are more dense, meaning you’ll need to water less frequently than if you have sandy soil, which is more aerated. If you are growing hydrangeas in containers, Pabst recommends selecting soil made for containers, which are more aerated than garden soil.

Sunlight

How much sunlight hydrangeas need varies by variety, but most thrive in partial sun. If you plant hydrangeas in an area that receives full sun, the soil will dry out faster, resulting in more watering. Hydrangeas grown in partial shade will need less water. 

Temperature

Hydrangeas require more water in summer when temperatures warm up than in spring and fall when the weather is mild. Pabst recommends checking the plants for drooping leaves, which is a clear sign that the plant is succumbing to hot weather and needs more water. 

Container Size

Large containers typically hold more moisture than small ones, meaning you’ll need to water hydrangeas less frequently the bigger the pot is. "In general, when planting just one shrub in a pot, opt for a pot that is double the size of the diameter of the pot your plant came in," says Pabst. She also says to choose a pot with drainage holes to prevent waterlogged soil.

Signs of Underwatering

You never want to underwater hydrangeas. Lorraine Ballato, gardener and author of Success with Hydrangeas, recommends trying the 'knuckle test' to gauge moisture levels. "Stick your finger into the soil. If it is damp at the second knuckle, you're OK. If not, start watering," she says. Aside from dry soil, here are other indications that your plant is receiving too much water. 

Drooping Leaves

An underwatered plant will typically have drooping leaves. "Consistently flagging leaves are a sure sign that something is wrong," says Ballato. This can happen after an afternoon of bright sun, but the problem is easily fixed with a good soaking.

The Flowers Are Drying Out

If the flower petals have begun to turn brown and crispy-looking, your plant needs water. Dried flowers are normal for hydrangeas towards the end of their life cycle, but not at the peak of the growing season. Newly brown flowers can perk up with water, but older ones should be removed. 

Yellowing Leaves

Yellowing leaves is another clear sign of underwatering. "Leaves could also turn yellow as a result of water stress," says Ballato. But unlike brown and drying flowers, the plant just needs a small amount of water to get it back on track.

Signs of Overwatering

Like underwatering, overwatering can be dangerous for hydrangeas. Here are some telltale signs of overwatering.

Drooping Leaves

Hydrangea leaves can also droop from too much water, says Ballato. To figure out the cause of the issue, check the soil. If the ground is soaked and the plant is in standing water, the hydrangea is getting too much water.

Fungal Growth

Too much water can result in fungal diseases like powdery mildew, which can cause your plant to develop white spots on the leaves. Fungi thrive in the wet, humid conditions created by watering your hydrangeas too often and can quickly spread to other plants.

Pest Infestation

Overwatered hydrangeas are also prone to attracting pests that like living in moist environments, such as aphids, small, wingless insects that feed on plant sap, killing the plant over time. The good news is that there are plenty of ways to protect your hydrangeas from pests, starting with not overwatering the flowers.

When and How to Water Hydrangeas

For optimal hydration, water your hydrangeas in the morning. "This allows the water to thoroughly soak into the soil and reach the roots before the heat of the day causes evaporation," says Pabst. If morning watering isn't possible, evening watering is the next best option.

In terms of how to water your hydrangeas, there is no 'one size fits all' approach, says Ballato. She recommends testing the soil to see if it is dry before watering. Then, depending on the soil and temperature outside that day, either do a light spray or a deep soak around the base of the plant.