Refreshing memories of a horticultural society set up by a group of First World War prisoners - plus, find out what else needs doing in the garden this week.

By Hannah Stephenson

More than 5,000 British citizens were interned in First World War civilian detention camp Ruhleben, an old racecourse outside Berlin.

It was described as 'scandalously inadequate', 'not fit to keep pigs in', and yet, amid all the horror, a group of green-fingered British men - who'd been living in Germany at the outbreak of war - decided to create something beautiful.

Forming a horticultural society, they set to work on the land to help feed their fellow prisoners, and with it, feed hope in the face of adversity.

This unique story, uncovered by the RHS Lindley Library, will be told in a new exhibition in October to commemorate the centenary of the First World War. The RHS is appealing to anyone who thinks a relative may have been one of these prisoners to get in touch (libraryenquirieslondon@rhs.org.uk) and share their story .

What the Society already knows about these brave men, who overcame long imprisonment and harsh conditions with crops and flowers, is fascinating enough, though.

At first the prisoners were put into the Tea House and stable buildings - some men were even crowded into a disused horsebox. Eventually barracks were built, but serious problems with catering soon led to food riots.

Some improvements were undertaken by the German authorities after a visit by the American ambassador brought conditions to wider notice, and forced them to limit damaging publicity.

But it was the prisoners themselves, and their love of gardening, which really transformed the camp.

Initially, horticulture was limited to a few British enthusiasts who made flower pots out of biscuit tins and developed rudimentary gardens outside their barracks. But a gift of seeds from the Crown Prince of Sweden sparked more ambitious plans; and the Ruhleben Horticultural Society was formed.

Within days of its first meeting, the secretary wrote to the RHS back in England asking to become an affiliated society. Stunned and amazed by this call from behind enemy lines, the RHS sent huge amounts of seeds, bulbs and advice to its new affiliate, deep behind enemy lines.

The members of the new society, eventually numbering more than 900, fed the camp's inmates, earned money to fuel its fledgling economy, disguised their bleak surroundings and organised RHS flower shows to boost morale.

One source from 1914 described the incredible scenes.

'The soil was dry, loose, dirty sand which rain quickly transformed into mud ... the camp was generally a cold quagmire, swept by piercing winds from Poland and the Pinsk marshes and interspersed with puddles, which swelled until they became lakes.

'Through this morass, men had to wade, three times a day, for a distance of at least a quarter of a mile to fetch their food from kitchens installed underneath the grandstand. Ruhleben was really a bit of England - a small British colony as it were, planted in the heart of the enemy's county.'

Despite the complaints about the food supplied in the camp, the first priority appears to have been to grow flowers - perhaps a basic human longing for beauty. Inmates grew chrysanthemums and dahlias which were shipped back to England for sale to raise funds for the camp. Others grew shrubs to hide the barbed wire.

In January 1917 permission was sought to create a vegetable garden. The RHS sent vegetable seeds which were planted out in March. In the society's first year, they grew many flowers including petunias, dahlias, chrysanthemums, stocks, lobelia, nicotiana and sweet peas, along with 20,000 lettuces, cabbages and cauliflowers, 500 celery plants, 600 tomato plants producing 300lb of fruit, 100 marrow plants, 36 melons and 72 cucumbers.

Problems with pests and securing good quality manure meant the first harvest was disappointing, but they still managed to sell food to the camp canteen and made some money to support their families back home, living in desperate poverty while their main breadwinners were interned.

And soon, their new garden was flourishing.

Promenade beds were planted alongside the barbed wire fences; members grew a total of 52 varieties of sweet pea and proudly sent photographs of their gardens back to the RHS. Then during 1917, the Ruhleben Horticultural Society organised competitions and held two flower shows - prizes were awarded for vegetables, cut flowers, sweet peas, table decorations, button holes, window boxes and gardens.

After the Armistice finally came, the camp was rapidly disbanded. In 1958 the racecourse and all its buildings were demolished, ironically, given the gardeners' difficulties in obtaining manure, to make way for a sewage works.

But while the plots themselves may be fone, the fascinating memory of the men who grew them lives proudly on.

Fiona Davison, head of libraries and exhibitions at the RHS, says: "The story of the Ruhleben Horticultural Society is completely unique, in that unlike many First World War histories that tell of the triumph of the human spirit over adversity, it is all but unknown."

:: The story of the Ruhleben Horticultural Society will be part of an exhibition on gardening during World War One to be held at the Garden Museum, Lambeth Palace Road, London SE1 in October 2014. It will go on tour in RHS Gardens in 2015/16.

Best of the bunch - Winter-flowering iris

There are so many varieties of iris from which to choose, but among my favourites are those which flower in winter, such as I. unguicularis (also known as I. stylosa), which grows to around 30cm (1ft) and is valued for its lilac winter flowers which appear from mid-autumn to mid-spring. It has rhizomes which can be grown in a border and should thrive in a warm corner under a south-facing wall. For a pint-sized star, go for the little rockery iris, I. reticulata, whose 10cm (4in) high flowers in shades of blue or maroon appear ahead of the grassy tufts of leaves. These bulbs should be planted in late autumn in a sunny, well-drained spot and are also ideal for planting in pots. They may be shortlived, and the bulbs don't often do brilliantly the second time around, but they are always worth the work.

Good enough to eat - Growing French beans under glass

You can sow extra early crops in a greenhouse in February, so get your French beans off to a good start, and choose carefully as the climbing beans are probably the most worthwhile this way. Sow two bean seeds per pot. They are large seeds so are easy to handle and should be pressed down into the compost until they are just out of sight. Once you've sown them, stand the pots on the staging of a frost-free greenhouse, where they will germinate. When they have filled their pots with roots, plant them 20cm (8in) apart in rows in the greenhouse border, which has previously been enriched with organic matter. Push a cane in alongside each plant and they should soon twine themselves around for support. With luck, you should be eating them months ahead of the same crops grown outside in the garden.

What to do this week

:: Cut back the dead stems of ornamental grasses such as miscanthus to ground level, avoiding any new green shoots which are emerging.

:: If weed seedlings are appearing, hoe them or pull them out by hand.

:: Pot up rooted hardwood cuttings of plants such as dogwood, taken last year, or simply plant them in the garden.

:: Sow radishes in the greenhouse border and thin to around 2.5cm (1in) apart when they are big enough to handle.

:: Mend broken trellis and fencing while plants are dormant and you have fewer obstacles in the way.

:: Put up a nest box, to coincide with National Nest Box Week which runs to February 21.

:: Plant stored dahlia tubers in boxes of potting compost in a frost-free greenhouse to give them an early start.

:: Order plug plants from specialist young plant catalogues.

:: Begin to feed plants in established borders using a controlled-release slow-acting fertiliser.

:: Check late potatoes you have in sore and rub out any sprouts which appear.

:: Force pot-grown lilies into early flower by bringing them into a temperature of 13C (55F).

:: Sow mustard and cress in shallow boxes on your windowsill and start the cress off four days before the mustard so that they are ready together.

:: Harden off polyanthus before putting them out once the weather turns milder.

:: Plant new rhubarb crowns in well cultivated soil and mulch with compost.