Smallholder tree cultivation and management is a common form of land-use in high-potential areas of Kenya. Some practices, such as the planting of trees on field boundaries, are strongly embedded in customary notions of land and tree tenure. Others, such as the planting of black wattle (Acacia mearnsii) woodlots, are more recent innovations, introduced to produce commodities for domestic and export markets. This study explores the economic dimensions of tree growing in Kenya, using land-use studies and the results form a household survey in the upper coffee/lower tea zone of Murang'a District. The study showed that households which grow woodlots operate larger parcels, are headed by older persons, and have fewer resident and more non-resident members than other households. Logistic regression modeling explored causal relationships, suggesting woodlots are more likely to be established as households age and as family labor becomes scarce.