Inkarho Rhododendrons are grafted on to a rootstock that produces a plant that will perform better on sandy and clay soils than plants grown on their own roots and also tolerate a higher soil pH. They are hardy and can withstand temperatures as low as -24ºC. The site chosen should be sheltered from strong, cold winds and in partial shade although the variety Fragrant Hedge White can be grown in full sun.
Planting in the garden
Dig out a planting hole three times wider than the rootball and half as deep as the rootball is high. Mix the soil removed from the hole with an equal amount of ericaceous potting compost. To this mixture well rotted leaf mould or garden compost can be added. Place a small amount of the mixture in the bottom of the planting hole so that the top of the rootball is just above ground level. Fill in with the remaining mixture lightly firming as you go so that the top of the rootball is at or just below the surface.
These varieties of rhododendron are more vigorous than plants grown on their own roots and need feeding more often. A general slow release fertilizer should be applied in April or early May. Where the plants are growing in a soil that has a pH higher than 7 they should be fed with a dressing of iron sulphate twice a year.
Planting in containers
The containers used should be approximately 10-20cm (4-8") wider than the width of the plant. Good drainage is essential and gravel , small stones or broken clay pots should be placed in the bottom of the pot. Use an Ericaceous Potting Compost and water the plant with rain water. Repotting the plant may be necessary annually in spring. During the growing season feed the plant with an ericaceous liquid fertilizer.
Care and Pruning
To promote new growth remove dead flowers. As the plants grow larger pruning and trimming may be required to maintain a good shape. This is done in early spring before new growth starts to appear.