In general, pecan trees in Texas fully ripen during a seven-week period from early October through the first week of December. Variety, health of the trees and environmental conditions may alter ripening times.
Weather and Tree Health
Weak trees with poor access to water and nutrients may produce a very short harvest, if any at all. Constant insect attacks or disease may forbear ripening altogether. Severe drought before pecans have ripened may set the ripening season back, or cause the nuts to drop before they even ripen.
Pecans bred for northern climates -- such as the Caddo, Pawnee and Osage varieties -- ripen earlier than those for East or West Texas. It's not recommended to grow these varieties in southern regions for an early harvest, since they are less resilient in southern heat.
Since the southern, coastal and central regions of Texas have the benefit of a longer growing season, healthy pecans ripen sooner in these parts. Far-West and North Texas may be two weeks behind or more.