Growing a hardy geranium in a pot

Which hardy geraniums to choose for containers or pots?

Prefer compact varieties that form a rounded bush, such as the geranium ‘Azure Rush’. You can also choose trailing geraniums like the hardy geranium ‘Bob’s Blunder’, whose stems will spill over the edge of the pot. While all species and varieties of hardy geraniums can be grown in pots, some (geranium sanguineum, cantabrigiense, cinereum, G. macrorrhizum, nodosum, or phaeum) tolerate this growing method better than others, accepting slight dryness of the substrate, provided they are placed in shade or in non-burning sunlight. The most suitable varieties are:

• The Geranium x cantabrigiense ‘St Ola’: it forms a lovely carpet of small white flowers, 15 to 25 cm tall, and fits easily on balconies, terraces, or in window boxes.
• The Geranium cinereum ‘Ballerina’: Its spreading habit and size of 20 cm tall by 30 cm wide make it an excellent candidate for potting. This dwarf geranium is distinguished by its uninterrupted pink flowering from May to August.
• The Geranium macrorrhizum ‘Czakor’: with its ultra-violet, very intense flowers, it thrives in pots both in shade and full sun.
• The Geranium sanguineum ‘Aviemore’: it forms a dense tuft of foliage, 20 to 30 cm tall, turning red in autumn, covered with large, bright mauve-pink flowers.
• The hardy geranium nodosum ‘Silverwoods’: it spreads as a carpet 30 cm high, dotted with white flowers, and will thrive in pots at the foot of walls without sunlight, along facades or terraces facing north or east.
• The hardy geranium phaeum ‘Raven’: with its almost black flowers and light green, acid foliage, it will not go unnoticed in adding colour to a terrace or balcony exposed to the North or East.
• The Geranium maderense: a spectacular giant, 1.5 m tall, very frost-sensitive, which needs to be planted in a pot and brought indoors for winter.

To help you with your choice, let our advice sheet guide you: “Hardy geraniums: how to choose them?”

Geranium cinereum ‘Ballerina’, Geranium x cantabrigiense ‘St Ola’ and Geranium maderense.

When to plant hardy geraniums in pots?

Planting a hardy geranium in a pot or container takes place in spring between March and May. Planting can also be done in autumn in regions with mild winters. It will flower within the year. Always plant outside of heatwaves and frost periods.

What pot for the hardy geranium?

Choose a pot that is at least 30 cm in diameter. Adjust the width of the pot to the chosen variety; you may opt for a hanging option as some hardy geraniums have a lovely trailing habit. All types of pots are suitable. A plastic container will be lighter and more economical. However, terracotta is preferable as it is more porate, facilitating water evaporation, which is ideal for this plant that requires well-draining substrate. Ensure that the bottom of the pot is well-drained to allow watering or rainwater to escape properly.

Terracotta remains a very good material, ensuring that the pot has drainage holes at the bottom.

What substrate?

Hardy geraniums prefer a light, well-drained substrate with no standing water. You can plant them in a mixture of equal parts of:

• ½ of geranium compost or potting compost
• ½ of river sand

Planting hardy geranium in pots

How to plant it in a pot?

• Soak the root ball in a basin filled with water to facilitate planting
• Spread a layer of gravel, clay balls, or pumice a few centimetres deep at the bottom of the pot
• Add the substrate mix until about halfway up the container
• Place the root ball in the pot without burying the collar too deeply
• Fill in with the remaining substrate
• Firm down
• Water

Hardy geranium ‘Rozanne’

What exposure is best for hardy geraniums in pots?

It depends on the variety; however, most hardy geraniums appreciate partial shade, especially in the warmer regions. Others thrive better in full sun. For example, Geranium sanguineum can adapt to all situations except very dense shade, while the hardy geranium phaeum will even do well in occasionally dry shade. During hot weather, feel free to move the pot to light shade to prevent the plant from suffering in the scorching sun. In general, prefer a partially shaded exposure for them.

Geranium sanguineum ‘Album’

How to care for hardy geraniums in pots?

Hardy geraniums are resilient plants that require very little maintenance.

Watering

While hardy geraniums can tolerate and even accept occasional lapses in watering once well-rooted in the ground, they will need more regular watering when in pots, as the medium dries out more quickly. We recommend watering at least once a week, and a bit more during the summer. They will be larger and more beautiful in soil that remains sufficiently cool. Allow the soil to dry well between waterings: excess water can cause the roots to rot. Be sure to increase water supply during prolonged dry spells to maintain generous flowering. Reduce watering significantly in winter, but do not stop completely.

Fertilisation

In the ground, the hardy geranium does not require fertiliser, but in pots, to encourage flowering, it will appreciate diluted liquid fertiliser for geraniums in the watering water every two to three weeks.

Pruning

Pruning helps control its growth and maintain a compact habit.

1. In mid to late summer, once flowering has finished, use a pruning shear to cut back severely; this will encourage new flowering in autumn.
2. Regularly remove faded stems and damaged foliage.
3. At the end of winter, cut back the clump with a pruning shear; new shoots will appear quickly.

Wintering

The hardy geranium is a very hardy herbaceous plant that can withstand cold down to -20°C, sometimes -30°C, and can spend the winter outdoors. However, in pots, the roots are more exposed to frost and winter moisture. We recommend placing the pot in a sheltered spot from winter rains to avoid any water stagnation around the roots in winter.

Repotting

After 2-3 years, when the plant has exhausted all its reserves, you can repot it into a slightly larger container. In the meantime, a simple top dressing in spring to replace the old compost with fresh will suffice.

For more tips, check out our article on repotting plants.