Latin Name: Apocynum x floribundum
Common Name(s): Hybrid Dogbane
Family: Apocynaceae
Size: 2 to 3 feet tall. Can establish large colonies by spreading rhizomes.
Life Cycle: Perennial
Distribution: Most of North America in sunny environments. Seems particularly fond of roadsides, swales, hillsides, and ditches in soil a bit moister than that tolerated by spreading dogbane.
Light Requirements: Full sun to partial shade. Seems to prefer full sun.
USDA Zone: 3a to 9b
Drought Tolerance: High once established.
Fire Risk: Presumably low while it is growing, given the soft watery leaves. If growing near a structure in a fire-prone area it is probably best to cut it down after it dies back and dries to avoid the seed fluff and dried plant matter fueling any fires.
Cultivation Notes
Apocynum x floribundum is a hybrid complex involving spreading and common dogbane, as well as another species A. sibiricum. Like other dogbanes, this is a rhizomatous species that does well in the garden with minimal care. It needs full sun and can adapt to a variety of soil conditions, but this dogbane in particular generally likes medium-moist soil and is not too picky about soil type provided it is not waterlogged during the winter. Once established the plants should do fine without summer irrigation, particularly in part shade, but make sure they receive regular water when young. Fertilization is definitely not needed, as the plants do fine even in poor and gravelly soil. Slug control may be needed when the plants are young, as heavy feeding by non-native slugs can kill young plants. Simply remove slugs in the evening and kill in soapy water.
Ecology
The interesting flowers bloom from June through August and are very attractive to pollinators. The seeds are consumed by birds in the winter, when few food sources are available.
Uses
This species is toxic, containing cardiac glycosides. It could presumably be used for fiber and the latex could be turned into rubber, similar to common and spreading dogbane. Do not consume.
Propagation
Seed or by division. Seeds are easily collected and can be sown directly in the fall or in spring. Sow just under the soil surface. Germination can be slow and often is irregular. If planting in the late spring, cold stratification will likely be needed for up to two months before germination will take place. I have not had too much luck with seeds, though. I have successfully propagated the plants by letting seedlings develop naturally, then moving them. I have also taken divisions with some success. They do not seem to resent disturbance as much as milkweeds, their close relatives.