How to Grow Rhodendrons in Your Garden

Rhododendrons, and the closely related azaleas, have almost everything; they’re fully hardy, and most have glossy evergreen foliage (although some are deciduous). The flowers are tubular or trumpet shaped, gathered in large trusses. In some varieties the individual trumpets may be up to five inches across. They appear in a wonderful range of colours – white blue purple gold orange or red blooms, often bicoloured, or with splashes of contrasting shades. Some, too are fragrant.

Individual rhododendrons have a relatively short, albeit brilliant, flowering season. However, collectively they produce a display which can last from early spring to early summer. For the rest of the year their rich green glossy foliage, like that of holly, provides an attractive backdrop for other ornamental flowering shrubs.

Their only disadvantage is that almost all of them need a lime free soil. With this qualification, there’s a rhododendron for every garden, however large or small. The largest, such as the rich red Rhododendron barbatum may reach a towering 40ft (12 metres), while dwarf varieties may be as small as 1ft (30cm)tall.

Cultivation

• Rhododendrons are naturally woodland plants, growing in a loose and friable, moist, well drained acid soil, and in the dappled shade of larger trees.
• If your garden has a neutral to lime free soil, plant rhododendrons in part shade as you would with any other shrub, digging plenty of peat or lime free ericaceous compost around the roots.
• Top dress annually with peat or leaf mould and feed with ericaceous compost or sequestrene.
• If your soil is alkaline, all isn’t lost. Create a raised bed or dig out a generous hole lined with permeable plastic and fill the bed with peat and ericaceous compost or other lime free soil. After planting top dress with ammonium sulphate in spring and autumn.
• However, creating an maintaining these conditions artificially demands continuing effort. An easier solution is to grow your rhododendrons in pots filled with ericaceous compost.
• Always water rhododendrons with rain water rather than hard tap water.

Rhododendron Species and Hybrids

There are more than 900 different species of rhododendron, and, as it’s very easy to create hybrids, many hundred more different varieties in cultivation.

Choosing from such a vast selection isn’t easy, but theses six popular and widely available varieties give an idea of the assortment available:

• Albert Schweitzer. Large Hybrid. Fine deep pink buds open to rosy-pink flowers with a dark reddish blotch in late May. A tough and hardy variety with an upright habit.
• Blue Diamond. Dwarf Hybrid. Mauve blue flowers in late spring.
• Carmen. Dwarf Hybrid. Deep red flowers in late spring. Not suitable for very cold areas.
• Cunningham’s White. Medium Hybrid. Pink buds open to white flowers with green or brown flecks. Flowers late spring/early summer.
• Harvest Moon. Medium Hybrid. Heavy trusses of cream/yellow flower with a pinkish flare in late spring.
• Praecox. Medium Hybrid, small leaved hybrid, and probably the earliest rhododendron to flower. Pink/purple clusters of flower in early spring.

Probably the easiest way to choose rhododendrons to plant in your garden is to visit gardens featuring them during the flowering season, such as Sheringham Park in Norfolk, or the Savill Garden at Windsor.

Other Similar Garden Plants

Other ornamental flowering plants for neutral to acid soil include azaleas and camellias.