Cultural hints

Ericaceous shrubs

Use any good quality ericaceous compost or use 75%good quality peat (AFP above 15) with 25% potting bark.

Add 2 to 3 kgs of Osmocote Plus12-14 month autumn formula or equivalent per cubic metre. Yellow flowered rhododendrons and dwarfs prefer the lower amount as they are salt sensitive.

Also add 1 Kg of Mag lime, and 1 Kg of Suscon Green to prevent vine weevil.

For spring potting we also add 0.5 Kg of PG 14-16-18 mix to provide an instant start (not needed in proprietory ericaceous compost which usually already has some fertiliser included).

Osmocote rates and longevities can be refined to suit growing conditions over time, but the above should be successful.

Prevent vine weevil with Suscon Green in the compost, or one of the new products which are on the way.

Spray against aphids if seen.

Evergreen azaleas can suffer from galls. - Keep well ventilated, pick off the galls. A preventative spray with Maneb or Zineb might help.

Spray against botritis and increase ventilation if seen.

Powdery mildew can occur, although we mostly avoid growing susceptible varieties. Symptoms - watermarking on leaves, followed by purple or brown spots then necrosis. Spray with anti-mildew spray several times if seen.

Brown edges to the leaves which then become necrotic suggests fertiliser scorch. Stand plants outdoors if not already, and water well. If too much controlled release fertiliser is in the compost, there is nothing that can be done other that copious watering to flush out excess salts.