Cross Pollinating a Viburnum Blue Muffin

Cultivar Selection

• "Blue Muffin" is not self-pollinating -- it must have pollen transferred from another plant in the same genus for successful fruiting. Grouping several "Blue Muffin" plants together does not improve fertilization either, but another V. dentatum cultivar, like "Chicago Lustre," matches well. Pollen with a different genetic makeup mixes with "Blue Muffin" grains to develop many fruits. Both plants prefer partial shade to full sunlight locations to take advantage of insect activity in the warm sun, as well as a relatively close bloom times. The majority of flowers on both plants should be open simultaneously for high fruit yields.

Natural Pollination and Spacing

• Although wind movement helps the pollination process, flies, bees and butterflies are attracted to the bright flowers for nectar sustenance. As the insects jostle the flowers, pollen grains adhere to their bodies and disperse to other blossoms as they feed. However, you must plant your two viburnum varieties close to one another. Insects conserve energy as much as possible when they collect nectar. Spacing these deciduous bushes too far apart discourages consistent insect activity and increases failed fruit development.

Hand Pollination

• If you have a particularly cool spring, regional insect activity may decrease because they need warm weather to keep their cold-blooded bodies limber for flight. As a solution, hand pollinate your "Blue Muffin" using a small paint brush or cotton swab. Simply swipe the tool against one cultivar's stamens and move the grains to the other variety's stigma. You can hand pollinate all of the flowers to ensure that some will produce fruits. Perform this process in the morning before the sun evaporates most of the surrounding moisture from the plant. Damp flowers hold pollen better for fertilizing success.

Pruning

• Avoid pruning your "Blue Muffin" until you know which limbs hold flower clusters. Removing stems before flowering causes the viburnum to have decreased blossoming and reduced fruits. Although "Blue Muffin" remains a small shrub throughout its lifetime, it can grow to 5 feet high with a 4-foot spread. Cut a few limbs from the shrub that do not contain any flowers to ensure your fruits will emerge in the fall.