I've tried many different plants in my clay strawberry pot, but it wasn't until I planted hens and chicks (Sempervivum) that I finally achieved success; they grew happily in it all season long.
Hens and chicks—also affectionately known as semps—are delightful plants. These low-growing perennials range from less than one centimetre in diameter to more than 10 centimetres, and clumps can spread up to 76 centimetres wide, making them ideal groundcovers. There are well over 60 species, some with white hairs covering their leaves, resembling a dense spider's web. Semps form compact clumps of rosettes in shades of green, red, purple, pink, yellow or grey. They are usually available in the alpine section of your local garden centre from spring until autumn.
Originating in the wilds of southern Europe, North Africa and western Asia, where they live under harsh conditions at high altitudes, semps can withstand temperature extremes. Many are hardy to Zone 4.
Hens and chicks can be grown singly or in mixed groups of different colours and will thrive in rockeries, raised beds and even narrow beds beside the house. They can also flourish when planted in terra-cotta pots, troughs, old logs, bricks or even the hollow pockets of concrete building blocks. Another good place to grow them is on a low roof, such as a shed.
Well-drained soil is essential and can be attained by adding grit (sand or small particles of stone) and gravel to your desired potting mix. To deter slugs, top-dress containers or the soil around outdoor semps with sharp grit gently pushed under the rosettes. Semps benefit from a light feeding of fertilizer, such as pelleted chicken manure, once or twice a year, but don't put the pellets on the rosettes, as they can be damaged.
Though semps will grow in shade, they require full sun to bring out the rich colour of their rosettes. Make sure they are not overshadowed by other plants, as this may also prevent full colour development. Whether they are growing indoors or out, winter is their dormant period, so keep semps quite dry during this period. In spring and summer, water when dry.
Semps have a profound ability to survive drought and display dazzling progressive colour changes throughout the year. Hues will fade in winter, but their brilliance will return in sunnier spring and summer weather. Rosette sizes and shapes will also vary. Even individual leaf shapes are different; some are fat and globular, others short and pointed, or long and tapered.