Tuberous stems are produced by the enlargement of the hypocotyl section of the seedling plant, but may include the first nodes of the epicotyl and the upper section of the primary root.
Tuberous stems have a vertical orientation with one or more vegetative buds produced on the upper end of the crown (arrow).
Plants with tuberous stems are perennial and new plants are usually produced by seeds although division of the tuberous stem is also possible.
Cyclamen (Cyclamen persicum) has a perennial tuberous stem but is usually propagated by seed.
Not all begonia species have tuberous roots, but tuberous begonia (Begonia xtuberhybrida) is an popular example of one that does.
There is a concentration of contract growers in Belgium that produce tuberous begonias for export companies.
They produce tuberous begonias from seed.
Tuberous begonia seed is sown in January in community flats in the greenhouse.
Established seedlings are transplanted to Styrofoam trays with a wider spacing for additional greenhouse growth.
Seedling tuberous begonias are moved into transplant flats at a uniform spacing in the greenhouse.
In May, greenhouse transplants are moved to outdoor field growing conditions. The flats are brought to the field and the entire flat tossed on to the surface of the soil at a very tight spacing.
Flat being tossed into place.
Transplants are shaded until they are acclimated to outdoor conditions. Contract growers produce saleable tuberous begonias in one year.
In some cases, growers will field plant one-year old tuberous stems to allow an additional year of growth to produce premium tuberous begonias for sale.