Gro 'n Sell
Gomphocarpus
Grow this one if you want to make your friends giggle. Also known as “Hairy Balls” or “Balloon Plant” for the less adventurous. Gomphocarpus physocarpus is actually a species of milkweed and can be a host plant for monarch butterflies. It will always be the hot topic of conversation in your garden or flower field. Stalks of large green pods can be used in arrangements and floral installations later in the season - they hold up well when the additional foliage is removed, just note that they do ooze a milky sap like common milkweed when cut.
About Tray Sizes
210 and 125 cell trays are full-sized trays, and three of these will fit in a shipping box.
50 cell trays are half-sized trays (unless otherwise noted) and two of these are the equivelent of one full sized tray. Six of these will fit in a shipping box.
18 and 32 cell trays are full sized trays specifically for our vernalized perennials. These have their own set of shipping rules (find details HERE) and cannot be combined with items grown in 210, 125, or 50 cell trays.
Growing Guides
Click here to access all of our comprehensive growing guides.
| Common Name | Hairy Balls, Balloon Plant, Cottonbush |
| Genus | Gomphocarpus |
| Species | G. physocarpus |
| Family | Apocynaceae |
| Life Cycle | Tender Perennial in zones 8-10 (grown as an annual in cooler climates) |
| Format | Plugs |
| Plug Care | Plant immediately after hardening off to avoid rootbound plugs. These are fast growing plants so don't hold them in their plug trays for more than a week after receiving them. Be gentle when handling roots to prevent damage, extreme root disturbance while transplanting can set the seedlings back (Milkweed, in general, do not like root disturbances). |
| Netting / Staking | These plants get very tall, but the stems and roots are strong and can generally grow unsupported. Space them properly to allow for healthy growth - if crowded they may grow weak and top-heavy which will put them at risk of toppling in the wind. |
| Temperature Range | Prefers warm temperatures (70-85°F). Not frost-tolerant; wait until all danger of frost has passed before planting outdoors in the spring. Plan to grow them as an annual in zones below USDA zone 8. |
| Spacing | For pinched plants, 24 inches apart is ideal to allow room for branching. Unpinched plants can be spaced closely together (6-12 inches) and each plant will be harvested as a single stem. |
| Soil Preference | Gomphocarpus thrives in well-drained, nutrient-rich soil with a neutral pH. Avoid overly wet conditions, which can cause root rot. Irrigate and fertilize regularly through the growing season for the best quality cut stems late summer/early fall. |
| Day Length | Short-day plants; plants require 12 hour days to flower. They will stay vegetative until the days are short enough to initiate flower. Pods develop quickly after flowering. Plant in FULL SUN. |
| Pinching | I prefer to pinch once, at the 5th or 6th set of leaves to encourage multiple side branches to grow. You can also choose to not pinch and plant your plugs more closely together. |
| When to Plant | Plant after the last frost date for your area. Warm soil temperatures are essential for optimal growth. |
| Harvesting | Harvest when the seed pods are fully developed but still green and firm. Avoid waiting too long, as pods may burst and lose their visual appeal. They develop red coloration on the pod when they are close to bursting. |
| Post Harvest Care | Cut stems should be immediately placed into cool water. Be careful if you have a sensitivity to plant sap as these milkweed have the typical sap that the plants are named after. Allow them to condition in the cooler before using. |
| Diseases / Insects | These plants are quite pest and disease resistant. Avoid overwatering as this can cause root rot. Watch for typical milkweed pests, such as aphids. |
| Bailey's Notes |
These plants make quite the statement in the field and in arrangements. Although they might look odd in a mixed bouquet, they are incredible additions to installations and event arrangements. I prefer to remove all the leaves on the stem to allow the pods to really shine. Pair with emerald tassel amaranth for an out-of-this-world look. An interesting observation with this species is that it can act as a host plant for Monarch butterflies. Although it is out of the native range of Monarchs, you might find caterpillars nibbling away on the leaves, and the caterpillars can successfully grow to maturity on Gomphocarpus. |
| Resources | Takii Culture Sheet |