Similarly, an ornamental cultivar of calendula, ‘Calypso Orange’, produced only half as much dry matter and flower buds at 32◦C compared to 20◦C (Warner and Erwin, 2005). Moreover, high temperature hastened anthesis and decreased inflorescence size by one-third in this cultivar. Clearly,calendula appears intolerant of temperatures that easily could be reached in shallow soil layers after late spring planting or by air temperatures during summer in temperate zones.