Serr

Serr is an early-leafing, lateral-bearing English walnut cultivar developed by the University of California, Davis, and grown especially in warmer, low-frost walnut districts. It is highly productive and yields large nuts with well-filled, light kernels of good quality. Serr is one of the earliest to leaf out, which makes it unsuitable where late frosts occur but advantageous in reliably warm regions with a long season. It is sensitive to a physiological disorder called pistillate flower abortion when overloaded with its own pollen, so managing pollination is important. Serr needs a pollinizer and hot summers to perform its best. Its heavy yields and large nuts make it a valued choice for orchards and permaculture plantings in hot, frost-free climates.