How to maintain healthy hydrangeas

Hydrangea pests and diseases to watch out for

Anthracnose

Anthracnose is like the plant version of a pesky cold. This fungal disease loves warm, humid weather – it spreads through spores and can get worse the higher the humidity. It messes with leaves, stems and fruits, leaving dark spots all over. To fight it off, trim the infected leaves off your hydrangeas and dispose of them. You can also apply some plant-friendly, copper-based fungicides to help get rid of it. Keep your garden clean to prevent future infections.

Powdery mildew

If you’re overwatering your hydrangeas, or if the environment is too humid, you may run into powdery mildew. It’s characterised by silver and black coloured spots on the top of the leaves that later develop into yellow spots. To treat it, remove the infected leaves with pruning shears and use a fungicide to stop the spread.

To avoid powdery mildew (or to keep it from returning), water regularly at soil level at the base of your hydrangeas and avoid water on any foliage. This helps keep the foliage dry, reducing the humidity around the leaves and minimising the chance of powdery mildew.

Botrytis blight

Another common fungal disease is botrytis blight, which shows up in the form of small wet spots on leaves or flowers that expand into brown, irregular blotches. To treat it, remove any infected leaves with pruning shears and discard them. Next, apply an organic fungicide or neem oil, following the instructions on the label for proper application.

A good preventative measure is ensuring your plants have good air circulation. Leave them enough space when planting and avoid overwatering to help reduce humid conditions.

Seasonal care for hydrangeas

Spring

Spring is the best time to nourish your hydrangeas for strong growth. They’re considered ‘heavy feeders’, which means they love extra nutrients. When growing hydrangeas, it’s best to apply a slow-release fertiliser and mix some compost or manure into the soil in early spring.

This is also a great time to add an organic mulch, which helps with moisture retention, weed suppression and temperature regulation. When the mulch breaks down, it contributes organic matter to the soil, adding even more nutrients for your hydrangeas to feast on. As your hydrangeas begin to bloom, don’t hesitate to remove weak or spindly shoots to make room for stronger growth over the summer.

Summer

Hydrangeas love moist soil, so your main focus over summer will be to make sure they get exactly that. Keep watering your hydrangeas as they start to bloom, preferably in the morning, with an extra top off in the evening if needed. You can use a watering can or garden hose to water at the base of the plants, or automate the process by installing a drip irrigation system to ensure a deep watering once a week. It’s a good idea to check what type of watering your hydrangea variety prefers, as some potted ones need daily watering in the summer. If your hydrangea flowers start to show signs of browning or wilting, grab a pair of shears and trim down to the nearest bud.

Hydrangeas are beloved for their gorgeous blooms, so make the most of them. They do great as cut flowers, in a lush centrepiece or as a surprise gift for family or friends. Cut the flowers in the morning, removing the lower leaves. Place them in tepid water as soon as possible. Adding some flower food to the water will help them last even longer.

Autumn and winter

Plant hydrangeas in early autumn so they’re able to establish a healthy root system before it gets too cold. Add an organic mulch to provide a layer of insulation, protecting the plant’s roots from cold temperatures.

Winter is best time to prune your hydrangeas. This is their dormant period, so pruning is advantageous for several reasons. It allows for shaping and restructuring while the plant is leafless, making it easier for you to see where you’d like to trim. Winter pruning stimulates new growth, so you’ll get a healthier plant come spring; it also encourages more flowering. Lastly, it helps with disease management because you’re removing any dead or diseased wood, as well as encouraging better air circulation which reduces the risk of fungal issues.

Tailor your pruning approach based on your goals. For taller hydrangeas, trim top growth slightly. If you’re looking at rejuvenating the plant and encouraging strong growth, you can take the branches all the way to the ground.

For more advice...

Check out how to grow and care for hydrangeas.