How to grow the watercress in a biological way
For the cultivation of the Watercress (Nasturtium officinale R. Br., 1812), also known as Pepe d’acqua, we must know that it is an aquatic plant, native to Europe and Asia, and in Italy it is everywhere on the shores of ditches and streams at sea level up to 1,500 meters.
For its cultivation it must start from the choice of the substrate; this must be that loose and very organic. The plant can easily be grown in the garden by picking small tufts from young spontaneous plants. They are transplanted into organic soil always kept moist. You can sow it first in peat jars and then carry out the transplant after having carried out a light digging to prepare the seedbed. Sowing should be done from the beginning of spring until September-October in loose substrate (earth, peat and sand in equal parts). It is sown broadcaster or in rows and about 3 grams of seeds are needed per square meter. Just break them a couple of millimeters.
The transplanting of the seedlings should be done, when these are about 5-6 cm tall, in small basins with at the bottom a layer of soil covered with a thin layer of gravel or expanded clay. Then add water, letting only the apical part emerge and place in a shady place. The watercress does not need any special fertilization, some mature manure or compost is more than enough; it can be added in succession to courgettes and tomatoes; is able to exploit the residual fertility of the soil without the need to fertilize.
Excellent is the combination with the radish that enhances the organoleptic characteristics of both crops and in this way does not require special cultural care if not to keep the soil moist without unnecessary stagnant water that could cause radical asphyxiation.
Among the adversities the only one that can create some problem, in dry years, is the flea of earth (Altica). For the altica two biological remedies to remove it are neem oil (if far from the collection) and the nettle macerate.
The plant is used for its leaves and soft parts and the harvest should be done in the summer for fresh or dried consumption. The period is the one that precedes flowering. But we must be careful about raw consumption because it can have liver problems.
Its use is for salads and soups or for flavoring soft sauces and cheeses; the taste is spicy and pleasant.