You may know Gomphocarpus by its common name, Hairy Balls (yes, really!) or by Balloon Plant, Cottonbush, or Swan Milkweed for those who take things a bit more seriously. Gomphocarpus physocarpus is a species of milkweed and is popular among monarch caterpillars and butterflies. This tender perennial is tall and fast-growing, with distinctive seed pods that add personality to your garden and to any arrangement.

Native to Southeast Africa, this plant likes heat and won't tolerate a frost, so get them in the ground only after the danger of frost has passed. Gomphocarpus wants to be planted in full sun, and prefers well-drained, nutrient-rich soil. Avoid overly wet condiitons, as this can cause root rot. Because it is so fast-growing, plugs will risk becoming root bound if held in their tray for more than a week after you receive them, so harden off and plant them right away.Mature Gomphocarpus has strong stems and roots, but in plug form they are quite tender. Excessive root disturbance can significantly delay their development, so be particularly gentle when handling the young plants.

Unpinched plants should be planted pretty closely, at 6-12 inches. Pinched plants will require more room for branching, and should be spaced at 24 inches apart. If pinching, it is recommended to do so at the 5th or 6th set of leaves to encourage plentiful side branches. Gomphocarpus is a short day plant, and requires 12 hour days to flower. It will remain vegetative until the days are short enough to initiate flowering, after which time the pods develop quickly. This is a relatively disease and pest resistant plant. Be mindful of over-watering so as to avoid root rot, and keep an eye out for the usual milkweed pests such as aphids.

Unpinched plants can be harvested as a single stem, while pinched plants will produce several smaller stems. Harvest when the playful pods are fully developed, green, and firm. As they mature, they will develop a reddish hue and ultimately burst. Place cut stems in cold water right away, and allow then to fully hydrate before using in design work.