Azaleas are rhododendrons — botanically the same genus, split in the garden by leaf and size rather than by family. What they share is the thing that decides whether you can grow them at all: they need acid soil, and on chalk or limestone they will yellow and sulk however well you feed them.
If your soil is wrong, a pot of ericaceous compost is not a compromise, it is the correct answer. Rainwater rather than tap water is the other half of it, especially in hard-water areas like London.
Evergreen azalea
Evergreen azalea
As rhododendron, keep the root system consistently moist and on acidic soil (or in ericaceous compost) from planting.
Care
Standard azalea siting.
Same shallow-root sensitivity as rhododendron.
Acidic, humus-rich, moisture-retentive soil, or ericaceous compost in a pot; generally more compact and pot-friendly than large rhododendrons.
Minimal — trim lightly to shape immediately after flowering if needed.
An ericaceous feed after flowering and a second in early summer, at half rate in containers where salts build up. Rainwater matters as much as feed — hard tap water raises the pH and undoes the fertiliser.
Semi-ripe cuttings in early summer are far easier than with the big rhododendrons: small shoots in an ericaceous, gritty mix, kept humid and shaded. Layering works too.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- AprilMain flowering season.
- AprilTrim lightly to shape immediately after flowering if needed. how ›
- NovemberMulch with an acidic, peat-free mulch for root protection. how ›
Months based on climate: UK. Your choice stays on this device.
- AprilMain flowering season.
- AprilTrim lightly to shape immediately after flowering if needed. how ›
- NovemberMulch with an acidic, peat-free mulch for root protection. how ›
Months based on climate: Northern Italy. Your choice stays on this device.
Common problems
How to spot it. On alkaline soil.
What to do. Use ericaceous compost or iron tonic.
How to spot it. Thickened, distorted leaves.
What to do. Remove and dispose of affected leaves.
Deciduous azaleaDeciduous azalea
Deciduous azalea
As other members of this genus, keep the root system consistently moist and on acidic soil (or in ericaceous compost) from planting.
Care
More sun-tolerant than evergreen types, since it loses its leaves and isn't at risk of winter leaf scorch.
Same shallow-root sensitivity.
Acidic, humus-rich, moisture-retentive soil.
Minimal — trim lightly to shape immediately after flowering if needed.
An ericaceous feed after flowering and in early summer. These are hungrier than the evergreen azaleas in the sense that they build a whole new set of leaves each year, but the rule against lime-based feeds is exactly the same.
Softwood cuttings in early summer, taken young while the growth is still soft, with hormone and bottom heat — they are noticeably harder than the evergreen kinds. Layering is the safer bet for one or two plants.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- MayMain flowering season, often with strong scent.
- MayTrim lightly to shape immediately after flowering if needed. how ›
- OctoberEnjoy autumn leaf colour, a bonus this group has over evergreen azaleas.
Months based on climate: UK. Your choice stays on this device.
- MayMain flowering season, often with strong scent.
- MayTrim lightly to shape immediately after flowering if needed. how ›
- OctoberEnjoy autumn leaf colour, a bonus this group has over evergreen azaleas.
Months based on climate: Northern Italy. Your choice stays on this device.
- AprilMain flowering season, often with strong scent.
- AprilTrim lightly to shape immediately after flowering if needed. how ›
- OctoberEnjoy autumn leaf colour, a bonus this group has over evergreen azaleas.
Months based on climate: Central Italy. Your choice stays on this device.
- AprilMain flowering season, often with strong scent.
- AprilTrim lightly to shape immediately after flowering if needed. how ›
- NovemberEnjoy autumn leaf colour, a bonus this group has over evergreen azaleas.
Months based on climate: Southern Italy and islands. Your choice stays on this device.
Common problems
How to spot it. On alkaline soil.
What to do. Use ericaceous compost or iron tonic.
How to spot it. Thickened, distorted leaves.
What to do. Remove affected leaves.
Popular varieties
Questions
Evergreen azalea: is it hardy?
Evergreen azalea: H4: Hardy through an average UK winter. It survives down to −10 °C. Deciduous azalea: H6: Hardy in the vast majority of UK gardens. It survives down to −20 °C.
Can it grow in a pot?
Evergreen azalea: Well suited to pots, often more so than large rhododendrons given their compact size. Deciduous azalea: With ericaceous compost.
Evergreen azalea: when do you prune it?
Evergreen azalea: Minimal — trim lightly to shape immediately after flowering if needed. In the calendar for UK, pruning falls in April. Deciduous azalea: Minimal — trim lightly to shape immediately after flowering if needed. In the calendar for UK, pruning falls in May.
Evergreen azalea: when does it flower?
Evergreen azalea: In the climate of UK it flowers in April–May. Deciduous azalea: In the climate of UK it flowers in May.
When do you feed it?
Evergreen azalea: An ericaceous feed after flowering and a second in early summer, at half rate in containers where salts build up. Rainwater matters as much as feed — hard tap water raises the pH and undoes the fertiliser. Feeding months, UK: April, June. Deciduous azalea: An ericaceous feed after flowering and in early summer. These are hungrier than the evergreen azaleas in the sense that they build a whole new set of leaves each year, but the rule against lime-based feeds is exactly the same. Feeding months, UK: April, June.