Most self-fertile crops benefit from having a second variety as a pollinizer. Cross pollination is known to increase fruit quality and yield. Most black currants cultivars are self-fertile, but will produce more fruit and larger fruit if you plant more than one cultivar. One study showed that all cultivars evaluated had lower fruit set when pollinated with their own pollen (Koltowski et al., 1999). Another study noted that self-fertility and pollination varies by cultivar, and the shape of the flower (in which the male portion is physically separate from the female portion of the flower), among other factors, and that self-pollination produced the lowest percentage of fruit. (Denisow, 2003). This study also noted the importance of insect pollinators, such as bees, in increasing pollination and fruit set, even flowers are pollinated by own pollen. All of this points to better fruit set with cross pollination and an abundance of pollinators.

Black currents will not cross-pollinate with red or white varieties, so to improve pollination of the ‘crandal’, you should choose another black currant cultivar for cross-pollination, and for the ‘cherry red’ you will need to select another red currant variety to improve pollination. You may want to consider planting some flowers or shrubs that invite and attract bees and other pollinators into your garden.