Pruning sour cherry trees is essential for maintaining their compact crown and ensuring continued fruit production. Unlike sweet cherries, sour cherry trees require more frequent and vigorous pruning due to their different growth habits. Understanding these distinctions and knowing the proper techniques can lead to healthier trees and bountiful harvests. Here’s what you need to know.
Why Sour Cherries Need Special Pruning
Many sour cherry varieties fruit primarily on one-year-old wood—branches that grew the previous year. In contrast, sweet cherries continue to bear fruit on three-year-old wood. As a result, sour cherry trees, particularly those of the « Schattenmorelle » type, need more frequent pruning. These trees tend to lose fruiting buds as their long shoots, or « peitschentriebe, » age, making it essential to cut them back to encourage the growth of new, productive branches.
The « Schattenmorelle » group, including varieties like ‘Morellenfeuer,’ ‘Vowi,’ and ‘Gerema,’ exhibit this behavior, which means they need strong pruning every year after harvest. These trees tend to lack the short, bud-heavy « bukett shoots » typical of sweet cherries, which is another reason they require different care.
Pruning Sour Cherries: Key Takeaways
Pruning sour cherries typically occurs immediately after harvest. Sour cherries are classified into two main types based on their growth habits: the « Schattenmorelle » type and the « Süßweichsel » (sweet sour) type.
- Schattenmorelle-type cherries need an annual, vigorous pruning of fruiting branches.
- Süßweichsel-type cherries, which grow more upright and are less prone to thinning, require less intensive pruning. Here, only fruiting wood older than three years should be removed to rejuvenate the tree and ensure continued fruit production.
Pruning Schattenmorelle Sour Cherries
Schattenmorelle-type sour cherries produce their best yields on one-year-old shoots. For this reason, it’s crucial to cut back the long fruiting branches each year. The best time to prune is immediately after harvesting, as this encourages strong growth of new fruiting branches for the next season. In some commercial orchards, a large portion of the fruiting branches is cut back along with the ripe cherries, streamlining the process.
As a general rule, about three-quarters of the long, fruiting « peitschentriebe » should be pruned back to a quarter of their original length, ideally cutting them just above a new side shoot. This approach ensures that the tree continues to produce new shoots and maintain its structure.
To prevent the tree from becoming too leggy, prune longer branches where you want a new fork or branch to form. Additionally, thinning older, stronger branches or removing them entirely helps improve air circulation within the tree. This also eliminates fungal spores that may cause diseases like Monilia shoot blight, a common issue for sour cherries.
Pruning Süßweichsel Sour Cherries
The Süßweichsel-type sour cherries, such as ‘Koröser Weichsel’ and ‘Karneol,’ grow in a more upright fashion and don’t develop the weeping shape seen in Schattenmorelle trees. These trees are better at branching on older wood and produce fruitful « bukett shoots » along their branches. As such, pruning is less intensive.
After harvesting, remove only weak or inward-growing shoots to maintain an open, healthy canopy. Avoid heavy cuts on the older branches unless necessary to shape the tree.
Pruning Hybrid Sour Cherry Varieties
Some sour cherry varieties, like ‘Ludwigs Frühe’ and ‘Dimitzer,’ exhibit characteristics of both types, with a less pronounced weeping shape and fewer bukett shoots. For these trees, pruning should focus on clearing out older growth to improve light penetration and air circulation. It’s also helpful to shorten certain branches to encourage new growth.
Conclusion
Proper pruning is vital for the health and productivity of sour cherry trees. By understanding the specific growth habits of different varieties, you can apply the correct pruning techniques. Whether your tree belongs to the Schattenmorelle or Süßweichsel group, regular pruning ensures a vibrant, fruitful tree for many years to come.