Tender perennial bedding
How to grow geraniums (pelargoniums)
Pelargonium × hortorum and others
The geraniums sold for pots and window boxes are pelargoniums: tender plants from South Africa, not the hardy border geraniums. Plant them out in late May after the last frost, in full sun and free-draining compost, and let the compost dry between waterings. They flower from June to October on a potash-rich feed. Before the first frost, bring plants indoors or take cuttings in August, because they will not survive a UK winter outside.
- Hardiness
- Tender, overwinter frost-free
- Position
- Full sun
- Soil
- Free-draining, not too rich
- Ideal pH
- 6.0 to 7.5
- Water
- Low to moderate, let compost dry between waterings
- Feeding
- Moderate feeder
Sowing and planting geraniums (pelargoniums)
WhenTake cuttings Aug to Sep; plant out late May; flowers Jun to Oct
Starting off
Take 8 to 10 cm tip cuttings Aug to Sep, trim below a node, remove lower leaves, insert in gritty compost and keep at 15 to 18 °C without a cover; they root in 3 to 4 weeks. Plant out after the last frost in late May. F1 seed sown Jan to Feb at 21 to 24 °C germinates in 7 to 14 days.
Spacing and planting
Plant 25 to 30 cm apart in beds, trailing ivy-leaved types 30 to 40 cm; plant at pot depth. Fine in a 20 cm pot or window box, and happier slightly pot-bound.
Varieties worth growing
- 'Frank Headley'
- Zonal type with cream-edged leaves and salmon-pink single flowers. Neat, free-flowering and attractive even out of bloom.
- 'Appleblossom Rosebud'
- Zonal with tight clusters of double flowers like tiny rosebuds, white edged pink. Best under cover or in a sheltered spot, since rain spoils the heads.
- Balcon (Decora) types
- The trailing ivy-leaved pelargoniums of continental balconies: single flowers in red, pink or lilac that drop cleanly, so little deadheading. For window boxes and hanging baskets.
- 'Lord Bute'
- Regal pelargonium with velvety near-black flowers edged in carmine. Flowers best in early summer and does better in a pot by the door than in open bedding.
- 'Attar of Roses'
- Scented-leaf type grown for foliage that smells of roses when brushed, with small pink flowers. Good on a windowsill and easy to overwinter.
Month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Sow F1 seed in a heated propagator. Keep overwintered plants almost dry and pick off dead leaves.
- February
Last seed sowing. Move plants into the best light you have.
- March
Cut overwintered plants back by half, repot into fresh compost and start watering. Take cuttings from the new shoots.
- April
Pot on young plants and pinch out tips to make them bushy. Start hardening off late in the month.
- May
Plant out or stand outside in late May, after the last frost.
- June
Begin the fortnightly feed. Snap off spent flower stalks at the base.
- July
Feed and deadhead. Let the compost dry between waterings.
- August
Take tip cuttings for next year's plants. Keep feeding.
- September
Last cuttings early in the month. Last feed.
- October
Bring plants indoors before the first frost. Cut back by half and remove any yellow leaves.
- November
Keep at 5 to 10 °C in good light with the compost barely moist.
- December
Check weekly for grey mould. Water only enough to stop the stems shrivelling.
Feeding geraniums (pelargoniums)
Pelargoniums flower best a little hungry and a little dry. Fresh compost carries them for the first few weeks; after that a dilute potash-leaning liquid feed through summer, and nothing at all from October to March.
A high-potassium feed for flowers; too much nitrogen gives leaf, not bloom. Let pots dry between waterings.
Feeding plan
March to May, potting up
Fresh peat-free compost
No added fertiliser. The nutrients in fresh compost last four to six weeks, and a rich mix gives leaf at the expense of flower.
June to September, pots, baskets and window boxes
3 ml per litre of water, the bottom of the label range, every 10 to 14 days: 27 ml in a 9 litre can. The label allows feeding at every watering, but pelargoniums do not need it.
June to September, plants making leaf and few flowers
Potassium Rich Fertiliser 11% K
Swap to 0.5 to 1 g per litre of water every 2 to 4 weeks: 4.5 to 9 g in a 9 litre can.
June to August, bedding in the ground
3 ml per litre once a fortnight on poor or sandy soil only. On ordinary border soil, nothing.
October to March
Nothing
No feed while plants are resting indoors. Start again four to six weeks after repotting in spring.
Signs to watch
Red-tinged leaves in spring
Cold nights, not a nutrient fault
Wait for warmth
Older leaves yellow and drop in a pot
Waterlogging or nitrogen short
Let compost dry, then a dilute balanced feed
Big leaves and few flowers
Nitrogen excess
Tomato-type high-potash feed only
Pests, diseases and problems
Yellow spots on the upper leaf surface with rings of brown pustules underneath, on zonal types
Pelargonium rust, a fungal disease that spreads in damp, still air
Pick off and bin affected leaves at once, water at the base, and space plants so air moves between them. Discard badly affected plants and do not take cuttings from them.
Cuttings turn black at the base and collapse
Blackleg, a rot encouraged by wet compost and a closed atmosphere
Bin them. Start again with a clean knife, fresh gritty compost and clean pots, water once, and never cover pelargonium cuttings with a bag or lid.
Grey fluffy mould on leaves, stems and old flowers, mainly in winter
Grey mould (botrytis) in cool, damp, stagnant air
Remove dead leaves and flower heads weekly, keep the compost almost dry from November to February, and ventilate on mild days.
Clouds of tiny white insects fly up from plants under glass; leaves sticky
Glasshouse whitefly
Hang yellow sticky traps, and in a greenhouse introduce the parasitic wasp Encarsia from April. Check plants before bringing them in for winter.
Plant wilts despite moist compost; white C-shaped grubs among the roots
Vine weevil grubs in the pot
Water nematodes into the compost in late August or September while it is still warm, and repot affected plants in fresh compost after picking out the grubs.
Corky brown bumps on the underside of leaves, most often on ivy-leaved types
Oedema, caused by more water at the root than the leaves can lose in cool, humid weather. Not a disease.
Water less, improve ventilation and space the plants. Leave the marked leaves on; new growth comes clean.
Pruning
Pruning and care
Deadhead by snapping the whole flower stalk off at the base. Overwinter in Oct before frost: pot up, cut back by half to 10 to 15 cm, keep almost dry on a frost-free 5 to 10 °C windowsill or in a greenhouse, and restart with water and warmth in Mar. Cut back again by half in Mar for bushy plants.
Good to knowOverwinter frost-free; deadhead and trim leggy growth.
Growing in pots
This is a container plant first and a bedding plant second. A single zonal fills a 20 cm pot; three fit a 60 cm window box; trailing ivy-leaved types go 30 cm apart along the front edge. Use peat-free multipurpose with a fifth of grit or perlite, and a pot with a free drainage hole and no saucer outdoors. Water thoroughly, then wait until the top 2 to 3 cm of compost is dry before watering again: more pelargoniums are lost to wet compost than to drought. Plants flower better when slightly pot-bound, so pot on one size at a time.
Common questions
Can I leave geraniums outside over winter in the UK?
No, bedding geraniums (pelargoniums) are killed by frost and need to come indoors in October. Cut them back by half and keep them on a cool, bright windowsill, in a porch or in a frost-free greenhouse at 5 to 10 °C, watering very sparingly until March. Hardy border geraniums are different plants and stay outside all year.
How do I take geranium cuttings?
Take 8 to 10 cm shoot tips in August or early September, cut just below a leaf joint and remove the lower leaves and any flower buds. Push them into pots of gritty compost, water once, and stand them uncovered on a bright windowsill out of direct sun. They root in three to four weeks without rooting powder.
Why are my geranium leaves turning red?
Red or purple tints on the leaves are nearly always a reaction to cold nights, most common in spring just after plants go outside and again in autumn. It is not a disease and the colour fades as temperatures rise. If it persists in midsummer in a pot, the plant is starved or pot-bound: repot it and start a dilute liquid feed.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.