How to grow hydrangeas

Inspired by a helpful YouTube guide. We based this walk-through on David Hurrion's hydrangea video "Hydrangeas". David is Associate Editor of BBC Gardeners' World Magazine and a regular at RHS shows, so this is well-grounded, practical UK advice covering the different types and how to treat each of them correctly.

1. Know which type of hydrangea you have

This is the starting point for everything. The main groups are:

Mophead and lacecap hydrangeas (Hydrangea macrophylla): the most common type, with large rounded flowerheads or flat lacecap flowers in blue, pink, or white. These flower on old wood - stems grown in the previous year. Pruning hard in spring removes all the flower buds.

Paniculata hydrangeas (H. paniculata): cone-shaped white or cream flowers that can be cut back hard each spring. They actually benefit from it - harder pruning produces bigger flowers. Much more forgiving to prune.

Arborescens (H. arborescens): also flowers on new growth, so can be cut back in early spring. The popular 'Annabelle' is this type.

2. Choose the right position

Most hydrangeas prefer dappled shade or morning sun with afternoon shade. They dislike the harsh afternoon sun in summer - leaves scorch and plants wilt badly. A position that gets sun from the east in the morning and sits in shade by midday is close to ideal.

That said, H. paniculata is more sun-tolerant than macrophylla types and can handle a more open position. In Kent, a south-west facing spot with some protection from a fence or wall works well for most varieties.

3. Prepare moisture-retentive soil

Hydrangeas are thirsty plants. They need soil that holds moisture without becoming waterlogged. Work in plenty of garden compost or well-rotted manure before planting. A mulch around the base each spring helps retain moisture and gradually feeds the soil.

Avoid very shallow, free-draining soil - hydrangeas planted there will need constant irrigation in dry summers. If your soil is sandy, add extra organic matter and mulch generously.

4. Understand flower colour and soil acidity

Blue or pink? For mophead and lacecap varieties, the flower colour is influenced by soil pH. In acid soil (low pH), the flowers tend towards blue. In alkaline soil, they go pink. Neutral or slightly alkaline soil - common in the chalky areas around East Kent - typically produces pink or mauve flowers.

You can shift colours by adding ericaceous compost and acidifying treatments for bluer flowers, or ground lime for pinker ones. This works best in pots where you control the compost. In open ground it takes sustained effort to move a chalky soil significantly acidic. White varieties stay white regardless of soil - they do not respond to pH treatment.

5. Prune mophead and lacecap types carefully

The rule: do not cut these back hard. In early spring, remove dead stems completely and cut out any weak or crossing branches at the base. The remaining stems should be tipped back only - cut just above a pair of strong buds. Leave as much of last year's growth as possible.

The brown dried flowerheads from the previous year are actually useful - leave them on through winter as they protect the buds below from frost damage. Remove them in spring when you can see new buds swelling.

6. Prune paniculata and arborescens types harder

These flower on growth made in the current year, so the approach is the opposite. In early spring, cut stems back to a framework of low, strong branches. How hard you cut determines the flower size - harder pruning (leaving fewer buds per stem) produces fewer but larger flower clusters; lighter pruning gives more but smaller heads. It depends on what you prefer and the space you have.

Time this pruning for when you can see the buds beginning to break, usually late February to March in Kent. Cutting too early in a cold winter can expose fresh wounds to frost damage.

7. Water well through the growing season

Wilting leaves in summer heat are a reliable signal that a hydrangea needs water. They bounce back quickly once watered, but regular wilting stress does affect flowering. In a dry summer, water deeply once or twice a week rather than little and often - encourage roots to go down rather than stay near the surface.

Pot-grown hydrangeas need far more watering than those in the ground - sometimes daily in hot weather. Use a large pot with good drainage holes, and water until it runs freely from the bottom.

8. Feed in spring and early summer

A balanced general fertiliser in early spring encourages good leafy growth. Switch to a high-potassium feed (tomato fertiliser works fine) from June onwards to support flower development and ripen the growth before winter. Stop feeding by August - late feeding pushes soft growth that may not harden off before the cold arrives.

When to call a handyman

Hydrangeas are garden jobs. But if you need a new border digging out, an overgrown shrub removal, or general garden tidying, Richard covers Sandwich and the surrounding East Kent area.