Perennial
Hardy geranium
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Flowers | Flowers in May | Flowers in June | Flowers in July | Flowers in August | Flowers in September | Flowers in October | ||||||
| Plant | Plant in March | Plant in April | Plant in September | Plant in October | ||||||||
| Prune | Prune in July | |||||||||||
| Looks good | Looks good in May | Looks good in June | Looks good in July | Looks good in August | Looks good in September | Looks good in October |
Overview
Hardy geraniums, often called cranesbills after the beak-shaped seed pods, are not the same as the tender bedding "geraniums" sold for pots, which are pelargoniums. The genus covers hundreds of species, from tiny alpines to knee-high border fillers. For a long season, look at Geranium 'Rozanne' with its violet-blue, white-eyed saucers, the magenta G. psilostemon with black centres, or the tough ground-covering G. macrorrhizum, whose leaves smell spicy when crushed.
Where to grow hardy geranium
Most cranesbills cope with sun or part shade and any reasonable soil, including heavy clay. G. macrorrhizum and G. × cantabrigiense will even knit together under shrubs and in dry shade once established, making them useful for awkward spots. Use the larger, sprawling kinds to soften path edges and fill gaps at the front of a border.
Planting
Plant pot-grown geraniums in spring or early autumn, setting them at the same depth they sat in the pot. Space them roughly 40–60 cm apart, as they spread sideways more than you expect. Water well for the first few weeks, then they rarely need help except in long droughts.
Care through the year
Spring
Clear any old, tatty leaves as new growth emerges and add a thin mulch of compost around the crowns.
Summer
When the first flush finishes and plants flop open, cut the whole clump back hard; fresh leaves and often a second round of flowers follow within weeks.
Autumn
Leave late-flowering types like 'Rozanne' alone until frost ends the show. Autumn is a good time to plant or move clumps.
Winter
Little to do. Many species die back to a low tuft; tidy away mushy foliage if it smothers neighbours.
Pruning
The mid-summer shear is the main job. Use shears to cut early-flowering types to a few centimetres above ground once they look untidy. 'Rozanne' and its relatives are best trimmed lightly instead, as they flower continuously on long trailing stems.
Propagation
Divide established clumps in spring or autumn by lifting them and pulling or cutting them into fist-sized pieces with roots attached. Species come readily from seed, but named cultivars will not come true and some, like 'Rozanne', are sterile.
Common problems
Generally trouble-free. Powdery mildew can whiten leaves in hot, dry summers; cutting back and watering usually fixes it. Slugs nibble young growth in spring, and vine weevil grubs can attack plants grown in pots.
Something else wrong? Diagnose it by symptom.
Month-by-month reminders
Jobs for this plant come round in March, April, July, September and October. Each month page lists everything else worth doing in the garden at the same time.
Related plants
Sources
Botanical names follow Kew's Plants of the World Online; growing attributes were checked against the references below. Text is our own. See our editorial policy.