Border phlox
Garden phlox
Garden phlox
Keep soil consistently moist through the first summer — one of the more drought-sensitive border perennials.
Care
Full sun to light part shade.
Dislikes drying out, especially in summer.
Fertile, moisture-retentive, well-drained soil enriched with organic matter.
Deadhead spent flowerheads to prolong flowering; cut back to ground level once foliage has died back in autumn; thin overcrowded stems in spring to improve airflow.
A balanced feed with a generous mulch as growth starts, and a second feed as the buds form. This is a thirsty, hungry plant — a starved, dry phlox is also the one that gets mildew.
Divide in spring every three years or so, keeping the outer growth. Root cuttings in winter are the trick worth knowing where eelworm is a problem, since they produce clean plants from an infested clump.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- AprilThin overcrowded stems to improve airflow and reduce mildew risk.
- JulyDeadhead spent flowerheads. how ›
- OctoberCut back to ground level once foliage has died back. how ›
Months based on climate: UK. Your choice stays on this device.
- AprilThin overcrowded stems to improve airflow and reduce mildew risk.
- JulyDeadhead spent flowerheads. how ›
- OctoberCut back to ground level once foliage has died back. how ›
Months based on climate: Northern Italy. Your choice stays on this device.
Common problems
How to spot it. Classic problem for this genus in dry summers.
What to do. Keep soil moist, thin stems, choose resistant varieties.
How to spot it. Distorted, stunted shoots.
What to do. Dig up and dispose of affected plants; don't replant phlox in the same spot.
How to spot it. On young growth.
What to do. Protect emerging shoots.
Creeping phloxMoss phlox
Creeping phlox
Plant in gritty, sharply-drained soil from the start; this group has no mildew anxiety like border phlox, but winter wet is a real risk.
Care
Needs full sun for a good flush of flowers and to keep the mat tight; avoid shade, which encourages leggy, gappy growth.
Drought-tolerant once established; sharp drainage matters far more than moisture — dislikes sitting wet, especially in winter.
Free-draining, gritty, poor to average soil; add horticultural grit on heavier ground. Tolerates chalk.
Shear back lightly immediately after flowering to keep the mat tight, encourage denser growth and set up next year's flowering.
No feeding needed on the sharp, gritty soil this wants. Fed, the mat grows soft and lush, then opens up and dies out in the middle after a wet winter.
Semi-ripe cuttings after flowering, or simply lift a piece of the mat where the trailing stems have already rooted into the soil and replant it — the easier of the two, and immediate.
Month by month
Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.
- MarchLight feed as new growth resumes, if soil is poor. how ›
- AprilMain flowering season — a dense carpet of colour.
- MayShear back lightly once flowering finishes to keep the mat tight and dense. how ›
Months based on climate: UK. Your choice stays on this device.
- MarchLight feed as new growth resumes, if soil is poor. how ›
- AprilMain flowering season — a dense carpet of colour.
- MayShear back lightly once flowering finishes to keep the mat tight and dense. how ›
Months based on climate: Northern Italy. Your choice stays on this device.
Common problems
How to spot it. Yellowing, collapsing patches, usually in winter — caused by poor drainage rather than a pathogen specific to this genus.
What to do. Improve drainage with grit; avoid planting in low-lying, moisture-retentive spots.
How to spot it. On young spring growth.
What to do. Protect emerging shoots, especially after wet weather.
How to spot it. Occasional orange pustules on foliage, less common than on border phlox.
What to do. Remove affected foliage; improve airflow.
Popular varieties
Questions
Border phlox: is it hardy?
Garden phlox: H7: Fully hardy anywhere in the UK. It survives below −20 °C. Creeping phlox: H6: Hardy in the vast majority of UK gardens. It survives down to −20 °C.
Can it grow in a pot?
Garden phlox: Prefers open ground for consistent moisture. Creeping phlox: Excellent in troughs, rockeries and sharply-drained containers — better suited to pots than border phlox, given its need for drainage over moisture.
Border phlox: when do you prune it?
Garden phlox: Deadhead spent flowerheads to prolong flowering; cut back to ground level once foliage has died back in autumn; thin overcrowded stems in spring to improve airflow. In the calendar for UK, pruning falls in October. Creeping phlox: Shear back lightly immediately after flowering to keep the mat tight, encourage denser growth and set up next year's flowering. In the calendar for UK, pruning falls in May.
Border phlox: when does it flower?
Garden phlox: In the climate of UK it flowers in July–September. Creeping phlox: In the climate of UK it flowers in April–May.
When do you feed it?
Garden phlox: A balanced feed with a generous mulch as growth starts, and a second feed as the buds form. This is a thirsty, hungry plant — a starved, dry phlox is also the one that gets mildew. Feeding months, UK: April, June. Creeping phlox: No feeding needed on the sharp, gritty soil this wants. Fed, the mat grows soft and lush, then opens up and dies out in the middle after a wet winter.