Affordable greenhouses have been proven to substantially increase crop yields by allowing farmers to grow year-round while, at the same time, decreasing water consumption. These benefits translate to improved livelihoods and food security for urban farmers and improved nutrition for their rural counterparts in resource-constrained areas. Accordingly, affordable greenhouses have been introduced to experienced and novice farmers in Kenya, Rwanda, Cameroon, Mozambique, Zambia, and Sierra Leone. Across these countries with different horticultural traditions, educational infrastructure and agricultural extension systems, there is a distinct knowledge gap on the basics of greenhouse farming. Even those who have previous farming experience need to rethink their strategies in order to transition more efficiently from conventional open-air farming to greenhouse farming. This problem has created the need for a comprehensive and context-appropriate decision-support tool to guide farmers through a series of questions across four phases of greenhouse operations: preparation, planting, nurturing, and harvesting. This article describes a highly visual decision support tool that educates farmers about important considerations and helps them make informed horticultural decisions. It also provides case studies for commonly grown produce like tomatoes, bell peppers and greens. This tool can be deployed on a computer, a tablet, or even a three-ring binder, and has been co-developed with, and validated by, farmer groups in Zambia.