Azalea flowers

How to grow rhododendrons

Find out all you need to know about growing rhododendrons, in this detailed Grow Guide.

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Plant
Plant

Do not Plant in January

Do not Plant in February

Do Plant in March

Do Plant in April

Do not Plant in May

Do not Plant in June

Do not Plant in July

Do not Plant in August

Do Plant in September

Do Plant in October

Do Plant in November

Do Plant in December

Flowers
Flowers

Plant does not flower in January

Plant does not flower in February

Plant does not flower in March

Plant does flower in April

Plant does flower in May

Plant does flower in June

Plant does flower in July

Plant does not flower in August

Plant does not flower in September

Plant does not flower in October

Plant does not flower in November

Plant does not flower in December

Take cuttings
Take cuttings

Do not Take cuttings in January

Do not Take cuttings in February

Do not Take cuttings in March

Do not Take cuttings in April

Do not Take cuttings in May

Do not Take cuttings in June

Do Take cuttings in July

Do Take cuttings in August

Do not Take cuttings in September

Do not Take cuttings in October

Do not Take cuttings in November

Do not Take cuttings in December

Prune
Prune

Do not Prune in January

Do not Prune in February

Do Prune in March

Do not Prune in April

Do not Prune in May

Do not Prune in June

Do not Prune in July

Do not Prune in August

Do not Prune in September

Do not Prune in October

Do not Prune in November

Do not Prune in December

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.

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Take a look at our Rhododendrons and azaleas Grow Guide, below.


Where to plant rhododendrons

Red-flowered rhododendron
Red-flowered rhododendron

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.


Propagating rhododenrons

Layering a rhododendron
Layering a rhododendron

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

Adding food to a container-grown azalea
Adding food to a container-grown azalea

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.

How to care for azaleas


Rhododendron and azalea varieties to try

Azalea 'Midsummer Coral'
Azalea ‘Midsummer Coral’
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  • 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.