Overlapping flowering
The selected polliniser must have an overlapping flowering period (see Figure 1). While two varieties may be compatible, if the flowering period for one is too early or too late for the other, successful cross-pollination will not occur.
Most apples require a certain number of hours of winter chill (below 7.2ºC) to break dormancy in spring and then flower, and requirements differ. Variation in winter chill from season to season can affect the degree of flowering overlap, particularly where the chill requirements of the two varieties are different. Select a polliniser variety with similar chill requirements to help ensure that flowering overlap is consistent from season to season.
The use of dormancy-breaking chemicals can affect flowering time, usually by shortening the flowering period and making it earlier. Consequently, this effect on flowering overlap should be considered when selecting a polliniser.
