Corn salad belongs to the Caprifoliaceae family. It is a winter and early spring plant. There are two cultivated species : Valerianella locusta and Valerianella eriocarpa which is more delicate and is mostly grown in Italy and the south of France. Corn salad also grows wild in Europe.
Corn salad is an autogamous plant : the flowers are hermaphrodite and self-fertilising, meaning they have the male and female organs within the same flower and they are compatible. There is, however, a risk of cross-pollination between different varieties by insects.
The Locusta and Eriocarpa species cannot cross, but you should be careful with wild corn salad which can cross with the cultivated varieties. To ensure the purity of the variety, it is better to leave 50m between different varieties of the same species of corn salad. This distance can be reduced to 30 m if there is a natural barrier such as a hedge.
Grow corn salad for its seeds in the same way as you grow it for consumption. You should sow out early in the autumn. It will then overwinter in the garden, flowering and producing seeds in the spring.
You need to grow 50 plants to ensure good genetic diversity. You should not pick any leaves from the plants you want to keep for their seeds.
Selection criteria include resistance to the cold, the size, shape and colour of the leaves, resistance to fungal diseases, late flowering. Make sure you get rid of badly formed plants that are not true to type.
The seeds mature slowly over a long period and fall easily once they are ready. You should therefore closely observe their maturity and not wait until the plants are completely dry. Ideally, wait until half of the seeds are mature before starting to harvest them. In order to avoid losing too many seeds when you harvest them, you should first of all spread a sheet on the ground around the plant. Let them dry in a dry and well-ventilated place for 2 to 3 weeks. To avoid the plants heating up, you should not dry them in piles that are too thick. You should keep a close eye on them during the drying process.
On a sunny day extract the seeds by rubbing the dry plants. Don’t try to take the very last small seeds, as they are probably not mature. Sort them by sifting them through different sized sieves to get rid of the coarser chaff and then the finer waste. You should then winnow them, for example by using the wind. At this stage the seeds do not have their final colour. They will darken during storing.
They have a dormancy period of 2 months, but the germination rate is best after one or even two years. You should therefore use seeds harvested in previous years.
Always put a label with the name and variety of the seeds as well as the year inside the package, as writing on the outside may rub off. Leave the seeds in the freezer for a few days to kill off any parasites.
The seeds of corn salad have an average germination capacity of 5 years. This will be even longer if you store them in the freezer.