Varieties may differ slightly in their minimum age
requirement before the "ripeness to flower" condition
is fulfilled. Observations during the 1971172 season
indicated that with N 52-219, flowering occurred in
fields which had been cut in December (or earlier)
and right up to the first few days in January. Fields cut
after this did not flower. With NCo 376, however,
observations have indicated that fields cut after 15-20th
December did not flower in 1972