Sunflower
Match the cultivar to the space — the same genus spans 30cm dwarf pot plants to giants over 3m, and the single biggest planning mistake is choosing seed for a giant sunflower in a spot or container meant for a dwarf one.
Care
Needs as much sun as possible for strong stems and large flowers.
Consistent moisture while establishing and through summer, especially for tall and giant cultivars supporting a lot of top growth; more drought-tolerant once well rooted.
Fertile, well-drained soil; tall cultivars benefit from soil enriched with organic matter before planting.
Not routine; remove the growing tip on multi-headed types if one large central flower is wanted instead of several smaller ones (disbudding).
A hungry plant, unlike most annuals here: feed fortnightly with a balanced liquid feed once it is growing strongly, switching to high potash as the buds form. A big sunflower needs a big root run and plenty of water to go with the feed.
From seed, sown two to a pot in mid-spring under cover or direct once the soil has warmed. Slugs take seedlings overnight, so a few weeks in a pot before planting out is worth the trouble.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- AprilSow seed direct once the risk of frost has passed, or start under cover earlier. how ›
- JuneStake tall and giant cultivars early, before they're at risk of wind damage — staking after they lean rarely fully corrects it. how ›
- AugustEnjoy the flowers; leave spent seed heads for birds in autumn rather than removing them immediately. how ›
Months based on climate: UK. Your choice stays on this device.
- MarchSow seed direct once the risk of frost has passed, or start under cover earlier. how ›
- JuneStake tall and giant cultivars early, before they're at risk of wind damage — staking after they lean rarely fully corrects it. how ›
- AugustEnjoy the flowers; leave spent seed heads for birds in autumn rather than removing them immediately. how ›
Months based on climate: Northern Italy. Your choice stays on this device.
- MarchSow seed direct once the risk of frost has passed, or start under cover earlier. how ›
- JuneStake tall and giant cultivars early, before they're at risk of wind damage — staking after they lean rarely fully corrects it. how ›
- AugustEnjoy the flowers; leave spent seed heads for birds in autumn rather than removing them immediately. how ›
Months based on climate: Central Italy. Your choice stays on this device.
- FebruarySow seed direct once the risk of frost has passed, or start under cover earlier. how ›
- JuneStake tall and giant cultivars early, before they're at risk of wind damage — staking after they lean rarely fully corrects it. how ›
- AugustEnjoy the flowers; leave spent seed heads for birds in autumn rather than removing them immediately. how ›
Months based on climate: Southern Italy and islands. Your choice stays on this device.
Common problems
How to spot it. Stem broken or badly bent, especially in giant cultivars.
What to do. Stake tall cultivars early, in a sheltered spot if possible.
How to spot it. Seedlings disappearing or badly chewed soon after sowing.
What to do. Protect direct-sown seedlings until a few true leaves have formed.
How to spot it. White coating on lower leaves in late summer.
What to do. Usually cosmetic this late in the season on an otherwise finished display.
Questions
Sunflower: is it hardy?
H4: Hardy through an average UK winter. It survives down to −10 °C.
Can it grow in a pot?
Dwarf cultivars do well in a large pot; giant types need open ground.
Sunflower: when do you prune it?
Not routine; remove the growing tip on multi-headed types if one large central flower is wanted instead of several smaller ones (disbudding).
Sunflower: when does it flower?
In the climate of UK it flowers in July–September.
When do you feed it?
A hungry plant, unlike most annuals here: feed fortnightly with a balanced liquid feed once it is growing strongly, switching to high potash as the buds form. A big sunflower needs a big root run and plenty of water to go with the feed. Feeding months, UK: May–July.