Nairobi, Sept. 9 -- When Kimani Rugendo talks about potatoes, he doesn't begin with the tuber itself but the business behind it.

This explains why his company, which built its name on juice cartons, is now reshaping how Kenya grows one of its most important staples.

Kevian Kenya Limited, the beverage manufacturer many Kenyans know from supermarket shelves, has spent the last decade evolving into a diversified agribusiness that develops potato seed, trains thousands of farmers, and processes produce at scale.

The company is 35 years old and employs more than 1,400 people across the value chain.

About a decade ago, the company realised that the raw materials feeding its beverage lines-mangoes, tomatoes, carrots, pineapples, oranges-were...