Why are my azalea leaves turning yellow?
Azalea leaves turning yellow? First, check which azalea you have.
Deciduous azaleas turn yellow and orange every autumn, which is normal. If an evergreen azalea has young leaves yellow between dark green veins, the soil or water is too alkaline and it cannot take up iron. Azaleas want pH 4.5 to 6.0. In the ground, sulphur fixes it; in a pot, ericaceous compost and rainwater.
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- Deciduous azalea, autumn: normal colour before leaf fall.
- Young leaves yellow, veins green: the pH is too high.
- Evergreen azalea in a pot, yellowing all over: check water, drainage and compost age.
Which yellow is it?
| What you see | Likely cause | What to do |
|---|---|---|
| Deciduous azalea yellowing in autumn | Normal autumn colour | Nothing |
| Newest leaves yellow, veins stay green | pH too high, often from hard tap water | In the ground: sulphur at up to 25 g/m². In a pot: fresh ericaceous compost |
| Older leaves yellow on an evergreen azalea | Normal shedding in spring and autumn | Nothing |
| Yellow and wilting, compost soggy | Waterlogging; azaleas have fine, shallow roots | Clear drainage; raise the pot; plant shallowly |
| Yellow and crisp, compost dry | Drought: shallow roots dry out fast | Water with rainwater; mulch |
Azaleas want pH 4.5 to 6.0 (RHS; Cornell). Rates as on our product page: University of Georgia and Cornell (established plants); Ohio State, Purdue and University of California (beds); RHS (pots). Never more than 73 g/m² in one dose on beds, or 112 g/m² a year on planted ground.
Work out your exact amount. Enter your area, your test reading and your soil type, and the calculator gives the dose, the timing and the bags to buy.
Fixing high pH
- Test first. Soil that fizzes with vinegar holds free lime: grow azaleas in pots of ericaceous compost.
- In the ground, sulphur. Up to 25 g/m² over the root area, early spring and late autumn, worked in lightly. Retest after three to six months.
- In a pot, fresh compost. Repot after flowering into ericaceous compost. No sulphur in pots (RHS).
- Rainwater, always. Japanese azaleas in pots are the classic victims of hard tap water.
Common questions
Why are my azalea leaves turning yellow after flowering?
On an evergreen azalea, a few older leaves yellowing and dropping after flowering is normal. If the newest leaves are yellow between green veins, it is the pH: test, then use sulphur in the ground or fresh ericaceous compost in a pot.
Will the yellow leaves turn green again?
Mildly yellow leaves can regreen once iron is available. Badly yellowed ones drop, and new growth comes through green.
When should I put sulphur round an azalea?
Early spring and late autumn, up to 25 g/m² a dose. It needs warm soil to work, so expect a season.
Can azaleas grow in chalky soil?
Not in the ground. Grow them in large pots of ericaceous compost and water with rainwater.
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Fix the soil, and the green comes back
Sulphur-bentonite pastilles that spread without dust and break apart when wet. Up to 25 g/m² around azaleas in the ground, spring and late autumn.
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Free UK delivery over £40. Buy now goes straight to checkout.
Free UK delivery over £40. Dispatched in 1 to 2 working days. Packed and posted from Stockport.