Rhododendron 'Merlin' (Glenn Dale)

Autumn · Outdoors

Apply mulch

Use bark chips or leaf mould to add an organic mulch around the crown of the plant.

A mulch is a covering that can: protect the soil surface from rain, heat and cold; deter weeds; provide nutrients. Organic indicates that material has vegetative origin e.g. manure, compost. Synthetics i.e. plastics, or stones are often called mulches.

Spring · Outdoors

Apply acidic mulch

Where soil is only just acidic, apply mulch with a high acidic content such as leaf mould, or mulch for ericaceous plants. Alternatively the plant can benefit from a feed of iron supplement (iron chelate) such as sequestrol.

Spring - late · Outdoors

Feed with slow release fertiliser for ericaceous plants

Apply a slow release fertiliser for ericaceous plants before applying any mulch, 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.

Outdoors

Water with rain water

This plant needs rain water or soft water (the minerals in alkaline or "hard" water are harmful). This is especially important for plants in pots.

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.

Planting

Deadhead blooms during flowering season

Remove flowers as they turn brown and fade. Snip the stem just below the bloom. This will keep the plant tidy and encourage more flowers.

The removal of spent flowers encourages the plant to produce fresh ones, rather than spend its energy on the development of seeds.

Compost · Planting

Ericaceous compost

Plants such as Camellia, Azalea and Rhododendron need acidic (ericaceous) soil. Where the soil is not acidic, or when planting in pots, use an ericaceous compost, or specialist compost for Camellia, Azalea and Rhododendron.