How to Grow Hardy Geraniums

Hardy geraniums are easy to grow and flower profusely year after year. They suit many garden styles and complement a wide range of plants, from spring bulbs to roses. Loved by pollinators (but not slugs!), these versatile perennials can find a home in almost any garden.

Many people think of geraniums as the brightly coloured bedding plants used to fill window boxes that shrink at the first sign of frost. Although commonly known as "tender geraniums", these plants are actually pelargoniums. The botanical genus Geranium is a different plant group altogether. To differentiate them from their tender cousins, they're often referred to as hardy geraniums or cranesbills.

Hardy geraniums are low-maintenance perennials that flower from late spring to autumn, depending on the variety. As their name suggests, they're fully adapted to our UK climate, meaning you can leave them outside all year round. Geranium flowers come in soft shades of blue, purple, pink and white, compared to the saturated pink, red and orange hues of pelargoniums.

 

Where to plant hardy geraniums

Hardy geraniums vary in size from diminutive alpines to four-feet-tall plants. Most popular cultivars fall somewhere in the middle, forming bushy mounds between 30 and 60 centimetres in height. Cranesbills are effective at suppressing weeds once established, and the dense foliage helps hide the less attractive parts of other plants, such as the bare stems of roses or the dying foliage of alliums and camassias. 

Almost all geraniums will thrive in light or partial shade, and many grow and flower well in full sun. Small, alpine varieties, such as Geranium cinereum 'Rothbury Gem' prefer full sun and free draining soil, making them well suited to rockeries and gravel gardens. Dusky cranesbill (Geranium phaeum) grows well in shade, including under trees and large shrubs, though it may not flower as well in deep shade. Geranium macrorrhizum and its cultivars are the best hardy geraniums for shade, and grow well in dry shade.

Geraniums can cope with any soil type, as long as the ground isn't waterlogged. Most geraniums prefer moist soil, with the exception of alpine varieties, but once they've established a strong root system, they are fairly drought tolerant.

You can grow hardy geraniums in pots, but it's best to choose compact cultivars or those better able to cope with dry conditions.

 

When to plant geraniums

You can plant hardy geraniums at any time of the year, as long as the soil isn't waterlogged. Early spring is the ideal time to plant geraniums, particularly if you have heavy clay soil, as this gives the plants a full growing season to establish before the winter rains hit.

 

How to plant cranesbill geraniums

Geraniums are very easy to plant. Water plants in their pots about half an hour before planting. You shouldn't need to add compost to your bed unless the soil is very poor or heavy.

Dig a hole a little larger than the pot your plant was delivered in. Remove the geranium from its pot and gently tease out some of the roots. Place it in the hole and backfill with soil. Water the plant well and add a layer of mulch.

Geraniums vary in size and spread. If you're planting multiple plants, make sure you space them based on their mature size.

 

How to care for geranium plants

Geraniums are hardy plants that can cope with cold winters and hot summers without too much care and attention. New plants need regular watering during the first spring and summer, but once they've settled in, you should only need to water occasionally during dry spells.

Geraniums grown in beds don't require feeding, but they will benefit from an annual mulch of compost or well-rotted manure in spring. You may want to give the plant another mulch with compost after chopping it down in mid-summer. Mulching is especially important for young plants that need consistently moist soil to develop strong roots.

You don't need to deadhead geraniums, but mature plants respond well to the "Hampton Hack", where you cut back the flowers and foliage to just above ground level after the plant has flowered in late June or early July. This tidies the plant up and encourages it to produce fresh new growth. You may even get a second flush of flowers! For young plants, just remove the flowering stalks to avoid shocking the plant.

Cranesbill geraniums are long-lived plants and can grow into large clumps. You can rejuvenate older plants by dividing them in spring or autumn.

 

How to propagate geraniums

The best way to propagate hardy geraniums is by dividing mature plants in early spring or autumn. Dig around the plant to loosen the soil, then dig up the entire clump. Depending on the size of the plant, you can use a spade or a sharp knife to divide it in half or into quarters. For larger clumps, you may be able to tease apart the roots to get more divisions.

Replant the divisions immediately, either in the ground or into pots, and water the plants well. They may look a little limp at first, but they'll soon perk up.

How to take cuttings from a geranium plant

While bedding geraniums (pelargoniums) are commonly propagated using cuttings, hardy geraniums are a little less reliable – that's why we suggest dividing plants if possible. However, if you don't have mature plants to divide or you want to create a large number of new plants, you can take softwood or rhizome cuttings.

Take softwood cuttings from young shoots in late spring or early summer. Cut healthy stems and trim them to short cuttings, with the base of each cutting just below a node. Remove all but a few leaves and dip the cuttings in rooting powder before sliding them into a pot of compost mixed with grit. Take more cuttings than you need, as it's likely not all of them will take.

If you're digging up a plant to divide it, you can take root cuttings at the same time. This works particularly well for cultivars of Geranium sanguineum and Geranium psilostemon. Select roots about a pencil's thickness in size and cut them into 4–5 cm lengths. It's helpful to make the bottom cut slanted, so you know which way up the cutting needs to be. Insert the cuttings into gritty compost so the top of the cutting is level with the surface and top with a layer of grit.

How to grow hardy geraniums from seed

Growing geraniums from seed can be a lengthy process. If you fancy having a go, choose species geraniums rather than cultivars and sow seeds in a tray of seed compost in autumn or early spring. Keep the soil moist and prick out seedlings once they have developed at least one set of true leaves.

 

Common problems

Hardy geraniums don't tend to get eaten by slugs, snails or rabbits, but they can get attacked by geranium sawfly larvae. These can be hard to spot, but you can check the underside of leaves from late spring and remove any you find. Although the munched leaves look unsightly, most plants recover.

Hardy geraniums may also be affected by powdery mildew, particularly if the weather is hot and humid. Plants grown in containers are susceptible to vine weevils.

 

Our favourite hardy geranium varieties

Geranium 'Rozanne' is an ever-popular, award-winning geranium that's prized for its long flowering period, from early summer through to autumn. The large, violet-blue flowers have pale centres and purple veins. Grow in full sun or partial shade.

Geranium phaeum 'Samobor' is a pretty dusky cranesbill with elegant, slightly nodding dark maroon flowers and green leaves that sport an unusual dark purple band. Geranium 'Samobor' is a good hardy geranium for shade, and while it prefers damp soil, it can cope with dry conditions.

Geranium 'Dreamland' flowers throughout the summer, producing masses of soft pink, veined flowers. An excellent groundcover option for beds in sun, light shade or partial shade.

Geranium 'Black and White' is a striking cultivar of meadow cranesbill (Geranium pratense) with deep purple-bronze foliage. The white flowers, veined with silver, sometimes have a purple tinge and bloom from late spring. Plant it in sun for the best colour – in shade, the foliage may be more green.

Geranium 'Max Frei' is a cultivar of the native Geranium sanguineum (bloody cranesbill geranium). It's a compact variety that forms a neat mound of green foliage which is dotted with purple-pink flowers in summer.

 

FAQ

Are geraniums perennials?

Hardy geraniums are perennial, which means they come back every year. Pelargoniums, which are commonly known as bedding geraniums or tender geraniums, are tender perennials, but are commonly grown as annuals, as they need to be kept indoors over winter.

Are geraniums poisonous to dogs?

Hardy geraniums (cranesbills) aren't listed as being harmful to dogs on either The Horticultural Trades Association's Guide to Potentially Harmful Plants or the ASPCA's toxic plants list. However, pelargoniums, which are the bedding plants commonly referred to as geraniums, do contain compounds that can be toxic to dogs. If your dog is unwell and you think they may have ingested plants from your garden, it's always best to check with your vet.

How do I deadhead geraniums?

Hardy geraniums don't need deadheading, though you can cut down mature plants after flowering in late June or July to get a second flush of foliage and flowers. Some varieties of pelargoniums (tender geraniums) benefit from having flowers removed. Simply snip the stems of faded flowerheads just above a leaf node to encourage fresh flowers to bloom.

Can you leave geraniums in pots over winter?

Hardy geraniums are fine to be left in pots over winter. As with any plants in containers, you may want to wrap pots in fleece or bubble wrap or move them to an unheated greenhouse if temperatures are extremely low. Tender geraniums (pelargoniums) can be left in their pots, but they need to be moved indoors or into a frost-free greenhouse for winter.

Are geraniums hardy?

This depends on the type of geranium. Hardy geraniums (which have the botanical name Geranium), also known as cranesbills, are fully hardy in the UK. Tender geraniums (which have the botanical name Pelargonium) are not hardy and will die if left outdoors over winter. You can either treat them as annual bedding plants or overwinter plants indoors in a frost-free greenhouse or conservatory.