In May, when the growing season is just beginning and the ground may look a little bare, bog rhubarb puts up round, yellow-green flowers. Like coltsfoot (Tussilago farfara), the flowers precede the leaves, only the scale is quite different. When bog rhubarb has finished flowering, the ground is covered with huge, lightly-toothed, kidney-shaped leaves on thick stalks. The Japanese have also eaten this rhubarb. Recent research has, however, discovered harmful and even dangerous substances in bog rhubarb, thus internal use is not recommended.
Bog rhubarb likes moist, humous soil and a sheltered spot, otherwise the giant leaves get torn by the wind. It spreads over time, and needs plenty of room to grow. Vegetative propagation is the only way of growing it in Finland.
Think twice before planting bog rhubarb, because it is extremely difficult to get rid of! Strong rhizomes may be found at a depth of over a metre. At Mustila we have stopped it spreading by planting it in a damp hollow at the top of the Azalea Slope: it does not try to spread because the surroundings are too dry.