Huisache ( Vachellia farnesiana (L.) Wight & Arn.) is a pest tree species on rangelands throughout South Texas and is expanding in range and density, due in part to prolific seed production. We aimed to determine the optimum diurnally-fluctuating temperature conditions for huisache seed germination by testing scarified and nonscarified seed in four temperature treatments: 35/25, 30/20, 25/15, and 20/10 degrees C. We used alternating 12-hour light/dark photoperiods in a growth chamber, and seed germination was recorded daily. Germination of scarified and nonscarified seeds at each temperature treatment was analyzed via ANOVA for a completely randomized design (with appropriate posthoc tests). Although total cumulative germination percentages were similar among temperature treatments, seeds in the 20/10 degrees C temperature treatment germinated more slowly. In addition, scarified seeds germinated more quickly, and with greater total percent germination. Results show that huisache seeds can be expected to germinate over a wide range of temperatures, with germination slowing when temperatures are low. Because we found huisache seeds germinated slowly in cooler temperatures, landscape managers may consider prioritizing control effort s of recently-germinated seedlings following warmer, wetter weather. (c) 2024 The Authors. Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )