Rhododendrons and azaleas are enduringly popular flowering shrubs. There are thousands of colourful cultivars to choose from, in a range of sizes to suit larger gardens or containers. From large blousy blooms in pinks and purples through to more fiery reds, oranges and yellows, they are guaranteed to put on a good show in early summer, as long as you provide the right acidic growing conditions. Many are evergreen, but the deciduous varieties will also provide good autumn colour.
Take a look at our Rhododendrons and azaleas Grow Guide, below.
Where to plant rhododendrons
Grow rhododendrons and azaleas in a sheltered spot in partial shade or full sun. Many cultivars suit plantings at the edge of a woodland or shady area. Smaller varieties look best at the front of a border, or in a container, to show off their colourful blooms.
How to plant rhododendrons
All rhododendrons and azaleas require humus-rich, neutral to acidic soil that’s moist but well-drained. Use peat-free ericaceous compost for containers. They’re shallow-rooted plants, so even the larger shrubs should not be planted too deeply – make sure the roots are just below the surface. Dig a hole that’s wider than it’s deep and back fill with leaf mould and ericaceous compost. Water well.
Species rhododendrons and azaleas can be grown from seed. But to propagate cultivars, cuttings and layering is the best option. Take heel cuttings of rhododendrons in late summer and autumn, and azaleas in mid to late summer. Layering is best done in late-summer.
Rhododendrons: problem solving
Rhododenron ponticum is on the invasive plant list, so should not be planted in gardens and should be removed where possible. There are no pests affecting rhododendrons and azaleas. However, the fungal disease rhododendron leaf spot can affect the leaves, causing them to drop.
Care and maintenance
Mulch rhododendrons in borders annually with an acid mix of leaf mould or conifer bark chippings. For container-grown rhodendrons and azaleas, replace the top layer of soil, or repot completely in spring and feed with an ericaceous fertiliser. Try to keep moist, but use rainwater as much as possible – tap water might contain too much calcium. There should be little or no need to prune.
Rhododendron and azalea varieties to try
- Rhododendron ‘Pleasant White’ – a dwarf, evergreen azalea with white flowers. It will suit a small garden, in a semi-shady border, or can be grown in containers.
- Rhododendron ‘Scintillation’ – a large shrub, growing to over 2m. The pink and apricot blooms are very exotic and it will brighten up any area in part shade. A very hardy cultivar, it’s a good for more exposed and northerly areas.
- Rhododendron ‘Nancy Evans’ – a gorgeous, golden-yellow compact rhododendron with leaves that are bronze when young but mature to a deep green. It looks good in a border and in containers.
- Rhododendron ‘Vulcan’ -a compact variety, with long leaves and large, scarlet blooms that will suit containers or a mixed border. It needs a sheltered spot in partial shade, and protection from winter winds.
- Rhododendron ‘Orakel’ – a hybrid with purple blooms with a crimson-red blotch. Hardy and compact it’s ideal for a mixed border or container display. Protect from harsh winter winds.
- Rhododendron yakushimanum ‘Kochiro Wada’ – one of a group of compact hybrids, this variety has white flowers, with silvery young leaves that mature to dark green. The Royal Horticultural Society has given it the prestigious Award of Garden merit (AGM).
- Rhododendron luteum – also known as Azalea pontica, this is a bushy, upright shrub with fragrant yellow flowers and good autumn colour. It can be toxic to people and animals but is good for bees that love the nectar rich flowers.