The technique of fruit thinning (removing some fruit from the tree while it’s still tiny) is one of the key maintenance jobs in spring. It’s so important it’s one of the 10 steps in our ultimate guide to fruit care.
Thinning has 4 main benefits:
- breaking the “on-again, off-again” biennial bearing cycle
- reducing pest and disease pressure
- growing larger, healthier fruit
- protecting the structure of your tree.
How does fruit thinning protect the structure of your trees? The key is removing the right amount of fruit.
How much fruit should you leave on the tree?
Most fruit in your fruit tree is carried on the small side shoots, or laterals, that grow from the main branches. As such, they are a very precious part of the tree and need to be protected.
Left to its own devices, your tree will often bear so much fruit on a branch or lateral that the weight breaks the branch. You can see this in the photos above and below (we have LOTS of these photos).
Your job when thinning is to remove some of the fruit that the tree has produced. One of the guiding principles of thinning is to leave only as much fruit as that part of the tree can easily carry.
Calculating the amount of fruit to remove when thinning
Try to imagine how large and heavy the fruit will be when it’s fully mature.
As a very rough rule of thumb, a short lateral can only bear the weight of one piece of fruit, and a longer or stronger lateral can carry two or more pieces.
However, this totally depends on the size of the fruit, and the strength of the lateral. You’ll need to make a judgement call in every case.
Of course, the actual amount of fruit you can leave on the tree depends on many variables:
- the type of fruit,
- the variety (cultivar),
- the ultimate size of the fruit at harvest,
- whether the tree is heavy, medium, or light crop,
- when it’s due to be harvested,
- age of the tree, etc.
It’s fine to just follow the rule-of-thumb guidelines we provide.
We also provide a more detailed chart in the Grow Great Fruit program and the Fruit Tree Thinning short course. The chart is designed to help you make a simple calculation that considers ALL the variables, which might just save you (and your trees) a few years of trial and error!
Assess how good your thinning efforts in spring were by checking the fruit quality and the health of your trees.
In spring the results of the grafting attempts in your fruit tree nursery become obvious, and it’s so satisfying when they’re successful!
Thinning cherry trees is not usually needed because they’re not prone to biennial bearing. That’s lucky, because it would be a huge job.