The flowering period of the Sussex apple varieties are shown by an F number, which indicates when a variety will be ready for pollination.
Honey bees, solitary bees, bumblebees and many other insects carry out the vital transfer of pollen from one tree to another.
Most apple varieties are not self-fertile and need to be planted near another variety that flowers at approximately the same time so that cross-pollination can occur.
F1 corresponds with the first of May and F29 the end of May, though these dates are only approximate and vary from year to year.
To be able to successfully pollinate one another, the F numbers of two varieties should coincide or overlap by 3 or 4.
If you are planting Sussex varieties next to Bramley’s Seedling, it is worth remembering that it does not produce viable pollen, so you will need to plant two other varieties to cross pollinate each other as well as the Bramley’s Seedling.
The very late flowering cooking apple, Crawley Beauty, is one of the few varieties which is self-fertile and will produce a good crop when planted on its own, though most varieties when planted in a suburban garden will set a good crop of apples because they have been pollinated from fruit trees in neighbouring gardens.