How to increase coffee berry weight

Nitrogen 

Nitrogen is needed for good growth, but too much at later stages of crop maturity can compromise coffee berry size. 

Potassium 

High supplies of potassium are needed during berry set and berry fill to maximize sugar accumulation in berry and eventual bean. Potassium has a crucial role to play in improving coffee berry size and quality through its role in the movement of sugars from the leaf for accumulation in the fruit. It is mobile in the tree and during peak periods of growth – particularly fruit fill – reserves in the leaves can soon become depleted, leading to dieback. 

Boron 

Foliar boron has a significant positive effect on coffee berry size – improving the quality grade of coffee beans. However, foliar sprays can provide a good, in-season top-up response, raising leaf levels such that coffee production and bean quality are maintained.