Hydrangea macrophylla 'Black Steel Blue'

Spring - late · Outdoors

Feed with sequestrol

If plants are acid loving and grown in soil with little acidity, or in a container, or are watered with limey tap water an annual feed with sequestrol (iron chelate) is highly beneficial. Follow guidelines on the packet. Will also 'blue-up' hydrangeas.

For hydrangeas that have good blue flowers in acid soil, this product can be used with alkaline soil to turn the flowers blue. This is most effective when the soil is neutral or just slightkly alkaline.

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 feed · Outdoors

Keep hydrangeas blue with rainwater & ericaceous plant food

Water blue hydrangeas with rainwater and feed them with ericaceous plant food. (Tap water and multi-purpose plant foods can make the blooms turn pink/red over time as they reduce the acidity of the soil/compost).

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.

Outdoor planting · Planting

Keep hydrangeas blue with ericaceous compost & acidic soil

Plant blue hydrangeas in a pot with ericaceous compost. When planting in the ground, check soil is acidic (pH 6 or less) using a soil test kit. If soil is ph7 or more, add Aluminium sulphite according to instructions and ericaceous compost to the hole.