Hydrangea macrophylla Black Diamonds Range

Spring - late · Outdoors

Feed with slow release fertiliser

Apply a general purpose slow release fertiliser, spreading it around the root area of the plant as it is coming into growth. (Or apply a liquid feed at regular intervals throughout the growing season.)

This is a simple way to provide a nutrient boost as a single annual procedure.

Spring-Autumn · Outdoors

Water to keep the soil moist

For best results, this plant needs soil that is always moist. Water deeply and regularly as soon as soil appears dry. Even for established plants in the ground, a dry week can cause problems with some soils. Check plants in pots more often, especially in hot weather. Or install an automatic irrigation system which will do the hard work for you, even when you are away on holiday.

Without regular watering some plants never fully regain their beauty.

Spring - early-mid · Planting

Prune old branches

On established shrubs, remove a third of the old branches to the base in early spring. Cut off old flower heads to a lower bud. This can be done every couple of years if the plant looks well-proportioned or is slow growing.

Outdoor planting · Planting

Add root growth stimulant to the planting hole

Mycorrhizal fungi helps roots establish quickly, so they absorb water and nutrients more efficiently. It comes as a powder, granule or gel. Add to the planting hole or container, and to the plant's rootball before planting in the hole. For "bareroot" plants use a gel.

Compost · Planting

Multi-purpose compost

Use a good quality peat-free multi-purpose compost when growing in pots and containers.