Hydrangeas diseases and pests
The database lists 3 problems recorded on this crop. 1 of them can cost the whole harvest, and 2 survive in soil or debris into next season — those are the ones that decide your rotation. The largest number are active in March.
Pressure through the year
The number of problems listed as active in each month. Pick a month to see what to sow, plant and harvest then.
Start from what you can see
What actually prevents them
Give the plants their full spacing 120×150 cm and keep the centre of each one open. Air moving through the planting dries the leaves faster, and leaf wetness duration is what turns a spore landing into an infection.
Applies to: Powdery Mildew
Rotate this bed and everything else in the same family on at least a three-year cycle. 2 of the problems below survive in soil or crop debris between seasons, so returning the same crop to the same ground hands them the host they were waiting for.
Applies to: Vine Weevil, Powdery Mildew
Clear and remove the spent crop at the end of the season rather than digging it in. Debris left on the surface is where the persistent problems overwinter, and next spring they start from your own bed rather than from somewhere else.
Applies to: Vine Weevil, Powdery Mildew
Keep watering and feeding even rather than generous. Several problems on this list are not infections at all: they are the plant reacting to a swing in water, temperature or nutrient supply, and consistency prevents them where no spray can.
Applies to: Iron Chlorosis
Every listed problem
Ordered by how much they can cost you.
Fungal diseases(1)
- Powdery MildewModerate
White to grey powdery coating on the upper surface of leaves and stems, later yellowing, curling and premature leaf drop. Fruit may be stunted or sun-scorched as the canopy thins.
- How it spreads
- Wind-blown spores
- Compost
- Hot compost only
- Conditions
- 15–28°C · humidity ≥60%
- First move
- Treat, then re-check in 5–7 days
Also at risk: Cucumbers, Zucchini, Peas, Pumpkins, Apple trees, Grapes
Pests(1)
- Vine WeevilSevere
Distinctive U-shaped notches bitten out of leaf edges of heuchera, bergenia, rhododendron and strawberry. Later, a plant wilts suddenly and lifts out of its pot with no roots at all, revealing cream C-shaped grubs with brown heads in the compost.
- How it spreads
- Carried by insects
- Compost
- Safe to compost
- Conditions
- 5–25°C
- First move
- Treat, then re-check in 5–7 days
Also at risk: Strawberries
Nutrient deficiencies(1)
- Iron ChlorosisModerate
Yellowing between the veins of the youngest leaves while the veins stay green (interveinal chlorosis); in severe cases new leaves turn nearly white with browning margins.
- How it spreads
- Not contagious
- Compost
- Safe to compost
- Conditions
- Spread by handling, insects or soil — not weather-triggered
- First move
- Fix the cause, not the leaf
Also at risk: Blueberries
Why rotation matters here
2 of these overwinter in the soil or in crop debris rather than on the plant. Pulling the sick plant does not remove them: they wait for the same host to come back to the same ground.