Climate change is making rainfall needed for horticultural production in Kenya more unreliable. Applied on-farm research and data from household panel surveys are collected within the framework of the interdisciplinary research project HORTINLEA, which stands for Horticultural Innovations and Learning for Improved Nutrition and Livelihood in East Africa. It is a research consortium of German, Kenyan, and Tanzanian universities and research institutes funded by the German Federal Ministry of Education and Research. Of 1232 surveyed smallholders, 87% perceive climate variability and change; 32% of major shocks experienced are weather-related often causing lower yields. Climate change adaptation is limited to incremental activities, such as crop portfolio changes. Transformative strategies, such as investing in micro-irrigation are rare. In this study, costs and benefits of climate-smart water management and its adoption potential are investigated. A subterranean micro-irrigation system has been constructed in Kenya from easily accessible materials (low-tech). Results indicate a water savings of 39–70% compared to watering can irrigation in vegetable production. Vegetable growth during dry spells, and the low-tech aspect attracted further smallholders to replicate this system.