Comparison of the growing season length and quality, at Bunda College on the Lilongwe Plain, Malawi, with the moisture requirement of the maize crop, indicate that the area is marginal for the widely-grown flint varieties. In the absence of shorter- season flint varieties, it is therefore essential to make a full use as possible of the season available. Two planting rules have been formulated, using standard agrometeorological procedures, to predict the earliest 'safe' planting date. If applied to the rainfall record for 1969-79 at Bunda, these rules would have resulted in a mean loss of six per cent (8 days) of the maximum possible growing season. Problems associated with the application of the rules, and method of extending the growing season are discussed.