To explore impacts of a demonstration garden-based agricultural intervention on agricultural knowledge, practices and production, food security and preschool child diet diversity of subsistence farming households.

Observational study of households new to the intervention or participating for 1 or 5 years. Variables measured were agricultural techniques learned from the intervention and used, agricultural production, household food insecurity (FIS) and child diet diversity (DDS), over one agricultural cycle (during land preparation, growing and harvest months).

Fifteen rural subsistence farming communities in Panama.

Households participating in intervention (n 237) with minimum one preschool child.

After 1 year, participants had more learned and applied techniques, more staple crops produced and lower FIS and higher DDS during land preparation and growing months compared with those new to the intervention. After 5 years, participants grew more maize, chickens and types of crops and had higher DDS during growing months and, where demonstration gardens persisted, used more learned techniques and children ate more vitamin A-rich foods. Variables associated with DDS varied seasonally: during land preparation, higher DDS was associated with higher household durable asset-based wealth; during growing months, with greater diversity of vegetables planted and lower FIS; during harvest, with older caregivers, caregivers working less in agriculture, more diverse crops and receiving food from demonstration gardens.

The intervention improved food production, food security and diets. Sustained demonstration gardens were important for continued use of new agricultural techniques and improved diets.