08 Jan 2024

How to grow hardy geraniums and best varieties

Adaptable, dependable and colourful, hardy geraniums deserve their popularity. Discover our best geranium varieties and tips for how to grow them.

Ceri ThomasEditor, Which? Gardening

In this article

Key facts
How to grow hardy geraniums: month by month
Best hardy geranium varieties
Full testing results for hardy geraniums
Caring for your plants
Common growing problems
How we test hardy geraniums

They’re surprisingly tough and very diverse, with varieties for almost every situation in the garden. Although many of them love the sun, plenty of varieties are said to be happy in shade, including tricky dry, shady areas.

Which? Gardening magazine grew a range of popular varieties to see which would give us the best display.

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Key facts

PLANT TYPE Herbaceous perennial

POSITION Shade or part shade

SOIL Dry or moist, depending on variety

How to grow hardy geraniums: month by month

January	February	March	April	May	June
		PLANT	PLANT	FLOWERING	FLOWERING
July	August	September	October	November	December
FLOWERING/CUT BACK

Best hardy geranium varieties

Which? members can log in now to see the full results and which are our Best Buy varieties. If you’re not a member, join Which? to get instant access.

Full testing results for hardy geraniums

Which? members can log in now to see the full results and which are our Best Buy varieties. If you’re not a member, join Which? to get instant access.

Hardy geraniums for sun

Variety name	Overall rating	Height x spread (cm)	Flower duration	Flower impact	Foliage impact	Ground coverage	Insect attraction	Garden worthiness	Pest & disease resistance
'Anne Thomson'
'Azure Rush'
'Blue Cloud'
'Dilys'
'Elke'
'Mavis Simpson'
'Nimbus'

The more stars the better. SCORE Ignores price and is based on: Flower duration 20%, flower impact 20%, foliage impact 15%, ground covering 15%, pest and disease resistance 10%, garden worthiness 10%, insect attraction 10%

Hardy geraniums for shade

Variety name	Overall rating	Height x spread (cm)	Flower duration	Flower impact	Foliage impact	Plant shape	Pest & disease problems	Bee attraction
'Brookside'
'Clos Du Coudray'
'Elke'
'Havana Blues'
G. maculatum f. albifolium
'Mount Olympus'
'New Hampshire'

OVERALL RATING The more stars the better. Rating ignores price and is based on: flower duration, 20%; flower impact, 20%, foliage impact, 20%; plant shape 20%; bee attraction 10%; pest & disease problems, 10%. Ratings given were taken during the second year of the trial. Height and spread measurements taken from trial plants grown in north London, when in full flower in the second year of the trial.

Tall hardy geraniums

Variety name	Overall rating	Height x spread (cm)	Flowering duration	Peak flowering	Flower impact	Foliage impact	Shape	Pest & disease resistance	Insect attraction
'Brookside'
'Eureka Blue'
'Johnson's Blue'
'Kashmir Blue'
'Mrs Kendall Clarke'
'Nimbus'
'Orion'

The more stars the better. OVERALL RATING Ignores price and is based on: shape 20%; flower impact 20%; peak flowering 15%; flowering duration 15%; foliage impact 10%, pest and disease resistance 10%; insect attraction 10%.

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Caring for your plants

Planting

Geraniums can be planted at any time of year, as long as the ground isn’t frozen. However, the widest selection of varieties will be available to buy in spring.

Plant in well-drained soil. Water them well after planting. Even the plants suited to dry soil will benefit from being watered until they’re established and growing well.

Help your plants with a recommended soil improver

Pruning

When the first flush of flowers finishes, cut the plants back hard. Fresh leaves will soon grow and you might get a second flush of flowers.

Tidy up the plants in spring by removing any dead growth from the previous year.

Discover our Best Buy secateurs

Dividing

If clumps grow too big, they can be divided in spring. This can be done every few years if needed. Dig up the clump and either cut it into sections or divide it with two forks, pushed through back-to-back.

Common growing problems

Powdery mildew

Powdery mildew appears as a white down on the leaves. Improving air flow and watering the plants can help to alleviate it.

Read more about powdery mildew

Rust

Rust appears as brown pustules on the leaves. Remove any affected leaves as soon as you see signs, or spray with a suitable fungicide.

Vine weevils

Vine weevil grubs like geranium roots. If plants look wilted but don’t recover after watering, check how firmly they’re anchored in the soil and look for the white, ‘C’-shaped grubs. Use nematodes to treat the problem and apply while the soil is still warm enough in late summer.

Read more about vine weevils

How we test hardy geraniums

The researchers at Which? Gardening magazine chose a range of geraniums and grew three plants of each variety in our trial gardens at Capel Manor, north London, and at Oatridge College in West Lothian, Scotland. After planting, we watered the plants until they were established, then left them to cope with any dry spells. For all varieties where the first flush of flowering ended in early summer, the stems were cutback to encourage a second flush of flowers. All the plants were grown for two years and assessed for how many flowers they, how long they lasted and how good they looked; how attractive the foliage of the plant was; how dense and attractive the form was; whether the plants were diseased or particularly prone to damage from pests; and how many bees visited the flower