The effects of different kinds of biotic and abiotic stress on crops can be lessened through exogenous application of different biostimulant products. Although some of these products come from enzymatic hydrolysates derived from animal remains, the literature does not contain references to the use of enzymatic hydrolysates obtained from animal hemoglobin, specifically porcine blood. With the aim of evaluating the effectiveness of a product obtained from the enzymatic hydrolysis of porcine hemoglobin (PHH) as a biostimulant that lessens the effects of thermal stress, two experiments were carried out in which lettuce plants (Lactuca sativa) were subjected to short-term episodes of intense cold and heat. After these episodes, different doses of the PHH product were administered into the growing medium. Moreover, in the heat episode experiment, one group of plants was first subjected to a heat episode and then administered a commercial biostimulant with the aim of comparing its efficacy with the PHH product. The biometric measurements carried out on the lettuce plants several days after being subjected to the episodes of cold and heat and then either administered or not administered the indicated treatments show that at the highest tested dose, the PHH product promoted a reaction that lessened the harmful effects caused by the intense cold and heat treatments.