This study evaluates the effects of temperature and aging on the efficacy of As2O3 at the 45th decimal potency in a wheat germination model, compared against a control and potentized H2O 45x. Each treatment–temperature combination was tested on seeds (Triticum aestivum L.) of Pandas variety, using six Petri dishes (33 seeds/dish) per trial, performing eight trials. Seeds were pre-treated by poisoning with 0.1% As2O3 solution to reduce germination, to allow a better evaluation of homeopathic treatment effects. The outcome variable was the number of non-germinated seeds after 96 h. Temperature effect was investigated by heating each treatment in a water bath for 30 min (at 20, 40 or 70°C), or for 5 min (at 100°C), and that of aging by dividing experimental data, collected over a period of nearly five months, into two groups: early and late experiments. Results seem to show that the efficacy of As2O3 45x is unaltered at 20 and 40°C, increases at 70°C and decreases at 100°C. As regards aging, a notable difference was found between early trials, with no significant efficacy, and late trials, where As2O3 45x exhibits a repeated significant effect versus control, except at 100°C. A reduction in variability was observed for As2O3 45x at 20°C versus control, confirming the findings of previous work. The main conclusion suggested by this experiment is that the efficacy of As2O3 45x on wheat germination may be influenced by heating degree and seems to have an increasing trend as a function of aging.