Gerrardanthus macrorrhizus is one of the best caudiciforms of the cucurbit family I have personally grown. Gerrandanthus macrorrhizus is indigenous to South Africa, where it can grow to an extremely large size. The caudex grows above ground where it can two to three feet in diameter.  I have seen plants planted in raised beds that are the size of a car tire! The vines will totally cover the caudex. My plants produce vines several feet in length. During winter here in So. California, my plants go dormant losing many of its leaves. The vines will stay green and produce new leaves in spring. Plants of this species are dioecious, meaning that plants have either male or female flowers only. You will need both male and female plants to produce seed. This is one of my favorite species to grow.

Culture

Gerrardanthus macrorrhizus is of easy culture. They are fast growing and fun to cultivate.  Keep the caudex shaded, but allow the vines to grow to full sun if you want. I have my plants under about 50% shade.  The vines grow up and onto the lath structure, where they will flower.  Full sun can burn the caudex and may lead to plant death. Use a well draining soil as with most caudiciforms, 50% in-organics, like punice or perilite and 50% organics.  Protect from cold temperatures. My plants have experienced temperatures in the mid thirty degrees Fahrenheit with no damage. Hold back on water during dormancy, watering less often. During the growing season I water once a week.  Light regular fertilizing will keep you plants healthy and growing strong.  I have had some plants rot out under their caudex. With careful care the plant can survive and have an interesting hallow caudex for display.