How to Grow and Care for Hydrangeas: A Complete Guide

Hydrangeas are beloved deciduous shrubs known for their stunning flowerheads, which come in a variety of shapes, from large balls to elegant cones. Popular varieties include mopheads and lacecaps, which feature rounded flowerheads in shades of white, blue, and pink during summer and autumn. Whether you have a small garden, a cottage-style space, or a modern urban setting, there’s a hydrangea to suit your needs. From compact varieties for containers to double-flowered and bi-coloured options, hydrangeas offer versatility and beauty. Some even flower twice a year or boast fragrant blooms and vibrant autumn foliage.

In this guide, you’ll learn how to care for hydrangeas, how to plant hydrangeas, and how to care for hydrangeas in pots, along with tips on pruning, propagation, and troubleshooting common issues.

Where to Plant Hydrangeas

Hydrangeas thrive in moist, well-draining soil and prefer dappled shade—neither too sunny nor too shady. Avoid south-facing spots, especially in dry soil. For shaded vertical surfaces like north-facing walls, consider climbing hydrangeas (Hydrangea anomala subsp. petiolaris). Since young growth is prone to frost damage, avoid frost-prone areas and protect plants from strong winds.

Hydrangeas grow well in most soil types, including alkaline and acidic soils. However, soil pH can affect flower colour in some varieties. For example, acidic soil can turn pink flowers blue. If you’re wondering how much sun do hydrangeas need, aim for a balance—too much sun can cause wilting, while too little can reduce flowering.

When to Plant Hydrangeas

The best times to plant hydrangeas are in spring or autumn when the soil is warm and moist. While summer planting is possible, it requires frequent watering to prevent the plant from drying out before its roots establish.

How to Plant Hydrangeas

Hydrangeas prefer moist soil, so if your soil is light, enrich it with organic matter like well-rotted manure or compost. Water the plant thoroughly before planting, and ensure it’s not planted deeper than it was in its original pot. After planting, mulch with leaf mould, compost, or manure, and keep the plant well-watered during its first spring and summer.

For climbing hydrangeas, train them onto galvanised wires initially. After a season, their self-clinging aerial roots will take over.

How to Care for Hydrangeas

• Watering: Hydrangeas need regular watering, especially during their first growing season. Use rainwater to maintain blue flowerheads.
• Mulching: Mulch annually in spring with leaf mould or compost to retain moisture.
• Feeding: Avoid overfeeding, as it can promote leafy growth over flowers. To change flower colour (e.g., pink to blue), use a low-phosphorus, high-potassium fertiliser or grow in peat-free ericaceous compost.
• Sunlight: Hydrangeas prefer dappled shade but can tolerate morning sun. Protect them from harsh afternoon sun to prevent wilting.

How to Care for Hydrangeas in Pots

Growing hydrangeas in pots is ideal for smaller spaces. Use peat-free ericaceous compost for blue flowers and ensure the pot has good drainage. Water regularly, especially during hot weather, and mulch to retain moisture. Repot every few years to refresh the soil.

How to Prune Hydrangeas

• Mophead and Lacecap Hydrangeas (Hydrangea macrophylla and Hydrangea serrata): Prune in mid-spring, cutting back to just above the top set of buds. Avoid hard pruning, as these varieties flower on old wood.
• Panicle and Smooth Hydrangeas (Hydrangea paniculata and Hydrangea arborescens): Prune in early spring, cutting back last year’s growth to 30-60cm. These types flower on new wood.
• Climbing Hydrangeas (Hydrangea petiolaris): Prune in summer after flowering, cutting back flowered shoots to new buds.

How to Propagate Hydrangeas from Cuttings

Take softwood cuttings in spring from non-flowering shoots with three sets of leaves. Remove the lower leaves, trim the stem below a node, and insert into gritty compost. Cover with a plastic bag and keep in a shaded, unheated greenhouse until roots form.

Troubleshooting Common Hydrangea Problems

• Lack of Flowers: Often caused by incorrect pruning. Follow pruning guidelines based on your hydrangea type.
• Frost Damage: Protect plants by leaving faded flowerheads over winter and pruning at the right time.
• Purple Leaves: Can result from temperature drops or phosphorus deficiency. Adjust soil pH or apply a phosphorus-rich fertiliser.
• Pests: Watch for hydrangea scale and vine weevils. Use organic insecticides if necessary.

Frequently Asked Questions About Hydrangeas

Can I Grow Hydrangeas in Shade?
Hydrangeas thrive in partial and dappled shade. In warmer regions, they can handle full afternoon shade if they get morning sun. Too much shade, however, may reduce flowering and weaken stems.

When is the Best Time to Move a Hydrangea?
Move hydrangeas during their dormant period, between mid-autumn and late winter, for the best results.

What Compost Should I Use for Hydrangeas in Pots?
For potted hydrangeas, use a soil-based compost like John Innes No.3 with added multi-purpose compost if needed. Ensure your pot has drainage holes to prevent waterlogging.

Tips for Buying Hydrangeas

• Check local gardens to see which hydrangeas thrive in your area.
• Consider soil pH if you want to maintain flower colour. For blue hydrangeas, grow in ericaceous compost.
• Verify the plant’s eventual size and growing requirements to ensure it suits your space.

By following these tips on how to care for hydrangeas outdoors and how to care for hydrangeas in pots, you can enjoy these stunning shrubs in your garden or on your patio. With proper planting, watering, and pruning, hydrangeas will reward you with vibrant blooms year after year.