Brassicas - The Manual of Seed Saving - page 54

and turnip all flower in the same garden at the same time, they will without a doubt cross-pollinate
each other.
GROWING FOR SEED Growing turnips for seed is not much different from growing cole crops (see
Brassica oleracea ) for seed. Traditional turnip cultivation involves seeding directly into stubble fields
after the grain harvest in mid to late summer, later thinning to 4-8 in. (10-20 cm) spacing. When
growing for seed, turnips can be selected directly out of those that are being grown for food. Turnips
can overwinter outdoors where temperatures do not drop below 15°F (−9°C) and humidity remains rel-
atively low in the winter. Otherwise overwinter in a root cellar, being certain to place only healthy, un-
damaged plants into storage. Simply pull selected plants from the ground in late autumn (do not prune
roots). Plant roots out in spring deeper than they were when harvested in autumn. Plants flower pro-
fusely, with stalks growing to be at least 3 ft. (1 m) tall, thus requiring support.
In some areas, overwintering turnips can be challenging due to their high water content, and suitab-
ility for storage varies from variety to variety. In areas with high winter humidity (as at Arche Noah),
turnips tend to rot in storage; we now overwinter young plants in pots. To do this, sow seed in pots in
late summer, such that they develop turnips about 1 in. (2.5 cm) tall. Place in hoop house, cold frame,
or other cold space that will not freeze too deeply. Cover the cold frame or similar set-up with straw
bales or bubble wrap if extreme cold threatens (remove when this danger has passed). Check planting
medium regularly throughout winter to assure that it is not too wet, yet does not dry out.
Ripe seedpods being threshed by hand
Those varieties that store less water and have tougher flesh (e.g., 'Blanc dur d'Hiver') can be over-
wintered outdoors where climate allows.
May turnips, when being grown for seed, should be planted in midsummer like regular turnips. In
order to select for quality May turnips, grow them again in the spring from time to time, make your se-
lections, and dig up soon thereafter. Dig up and move plants several times until autumn to stunt
growth, prevent cracking, and help plants make it to and through the winter.
Turnip greens, those “turnips without turnips,” develop seed in the first year of cultivation.
HARVEST Seed harvest and processing instructions as for Brassica oleracea . Ripe seedpods of B. rapa
crops explode, releasing their seed to the ground, so harvest before pods attain full ripeness.
Turnips in South Tyrol, Italy