I have two different elderberries that I would like to prune.
1. The first is a ‘Sutherland Gold’ (a cultivar of Sambucus racemosa) that is 5 years old, and I have never pruned it.
2. The second is a ‘Black Beauty’ (a cultivar of Sambucus nigra) that I just bought last year.
When should I prune? At what point on the stems? How far from the ground?
I consulted Peter McHoy’s Practical Guide to Pruning, (Abbeville Press, 1993), and he recommends cutting one stem in three in mid-spring on plants that have been established for three or more years. You would cut to just above the ground level, choosing to prune out the oldest and weakest shoots first. Continue with cutting out shoots that will open up the center of the plant or improve its shape. It may look sparse afterwards, but new shoots will grow and fill in the space.
If you are growing the plants mainly for their foliage, he suggests cutting all the shoots back to 1-2 inches from the framework of the old wood in mid-spring.
Below is some more detailed information from the website of the Ontario Ministry for Agriculture, Food and Rural Affairs, which assumes you are growing the plants for their fruit production.
Pruning:
“During the first two seasons plants should be encouraged to grow vigorously with little to no pruning required. After the second year, pruning should be done annually in early spring. All dead, broken and weak canes should be removed. Three-year-old canes should be removed as they produce less fruit and appear to be more prone to winter injury. Removal of older canes will encourage the growth of new, more fruitful canes.
“Mowing of all the canes in a mature planting may be a method of reducing labour costs while encouraging growth of new canes. The disadvantage of this system is that there is a loss of production in the season following mowing as there is limited production on the one-year-old canes.”