She is a bit of a diva,” says Mathias Peters explaining the tender loving care he bestows on his Convallaria majalis. Mathias is the fifth generation of farmers in this part of northern Germany who have dedicated part of the family dairy farm to growing this particular plant, better known to many as lily of the valley.
In Kirchwerder, between the Elbe and the Gose-Elbe, on the outskirts of Hamburg, German farmers have been growing the plant they call maiglöckchen (May bells) for centuries. They are not grown for the flowers, in fact any flower that dares to raise its head above the soil is immediately discarded. Mathias wants nature to concentrate its force below ground. This is where the plant multiplies, sending out rhizomes, at the end of which a ‘pip’ will work its way up. This pip does not flower in the first year, when it only produces leaves. In its second year, it contains the beginnings of the fragrant, bell-shaped flowers. And it is the rhizomes with the flower pips that Mathias sells, mostly to Dutch traders who sell them on to companies that force Mathias’s crop into flower.
“Eighty per cent of the lily of the valley we grow ends up in France,” says Mathias. This is because the French are mad for muguet, as the plant is commonly known there, where it is traditionally given to loved ones on May Day. In 2015, the French spent €23.6 million on sprigs of lily of the valley. Making sure there is enough supply to meet this huge demand starts at Mathias’s farm, among others. Here, the moisture and shade-loving Convallaria majalis begins life in surprisingly sandy soil that is exposed to full sunlight. “Some growers experimented with tarpaulins for shade,” says Mathias. “However, it didn’t make a blind bit of difference.”
In late September and October, once the leaves have withered, Mathias harvests his crop. A dainty, little harvester cuts through the tangled mass of fibrous roots, some 20cm below the surface. The rest of the process is carried out by hand. In one of the sheds, the remaining soil is shaken off and the web is untangled into more manageable clumps – if necessary, by impaling it on a spike and pulling hard. Those clumps are then moved to a sorting table, where local women sort the pips into the one-year-olds that only contain leaves – these will be replanted – and the two-year-olds that contain flowers and will be sold. There is a third stack of crates, in which the less-than-excellent rhizomes end up, and Mathias confesses that many of these misfits end up in garden centres across Europe where they are sold on to unsuspecting gardeners.
Distinguishing between a flower pip and a leaves pip is a job done by feel. The experienced fingers of the women gently squeeze the pips, and if it feels as if it contains a tiny marble, they know it’s a flower pip. Once sorted, the pips are graded according to size. Wooden blocks, each with 25 holes, represent those different sizes. It’s a matter of pushing 25 same-sized pips into those holes and then bundling them up with a rubber band. Although Convallaria majalis are not prone to disease, they may contain aphids. “Which is why we then ‘cook’ them,” Mathias explains. “Animal protein dies off at 43.2°C, vegetable protein at 43.3°C. Obviously, we don’t want the latter but it is impossible to be that precise with the water temperature. So, we dip the crates in water that is 44°C and then dip them in cold water to prevent the heat from penetrating too far.” The crates are then placed in cold storage at 5°C, awaiting transportation. The remaining rhizomes with the leaf pips go back into the earth, with Mathias replanting them 4cm apart against the ‘dykes’ thrown up by his trench-digger, then covering them with soil in a similar fashion to asparagus (to which Convallaria majalis is related). One year later, he will do it all over again: harvest, sort, sell and replant.
The company that buys Mathias’s crop freezes the Convallaria majalis to -2.5°C and then thaws out portions as they are needed. They are then planted in wooden crates, and placed in a dark room at 20°C. Hot water pipes run underneath to stimulate growth. After a week, the crates are moved on to a table with hot water pipes above, teasing the plants upwards to seek out the warmth. Once tall enough, they will receive natural light, and in two days the yellowish leaves turn bright green and the sweet-smelling flowers come into bloom. They are then bundled up, roots and all, and shipped off to the flower auctions, just one step away from your vase or wedding bouquet.
How to grow your own Convallaria majalis or Lily of the valley
Expert grower Mathias explains the best way for gardeners to grow their own lily of the valley
• Be careful when handling Convallaria majalis because every part of the plant is poisonous, especially the berries, which may look attractive to children and pets.
• Before planting, soak the pips in tepid water. Plant rhizomes 7-10cm deep and 20cm apart, making sure the pips are covered.
• After planting, water generously. To promote spreading in the first year, pick any berries as soon as they appear – washing your hands afterwards – as this prevents the plant from putting its energy into creating seed. Divide and replant congested colonies in autumn, applying a generous mulch of composted leaf mould.
• Convallaria majalis is the perfect ground cover as it will spread, but you can keep it in check by burying a 25cm-high, thick plastic ‘rim’ around the preferred area. Or plant in large (10-15-litre) containers, buried in the ground. If you choose the latter option, dig them up every five years or so to thin them out.
• Despite its shade-loving reputation, Convallaria majalis also does well in full sun, but it is better suited to cold climates. It will bloom best after a hard cold winter, and although tolerant of poor soils, it prefers a rich, moist but well-drained soil. It tends not to bloom in very deep shade.