Senna hebecarpa
Wild Senna
- Full sun to very light shade
- Average to dry soils - hosts nitrogen fixing bacteria
- 3' to 5' in height, 2' to 3' in width (may be wider in richer settings or with limited competition) I haven't found that these spread but they can self seed beyond what some gardeners are comfortable with.
- Hot, suny gardens and meadows.
These spent a few years slowly maturing from seedlings in the nursery bed in my urban backyard before finally being moved to a permanent home in the sunny Perth meadow. If their first year was anything to go by, they were very happy with the change in setting. Dry, sandy soil in a hot, sunny spot seems to be just their speed.
Their woody stems grow to around 4’ tall each year, resprouting from the roots every spring. This year to neared what I suspect will be a mature width of around 3’.
They don’t offer nectar, but their summer blooming and abundant pollen makes them popular with bees gathering for their nurseries, where the pollen makes up the larval food for most (if not all) infant native bees.
July blooms are followed by seed pods in August. The pods start out an almost translucent green and dry to black-brown and hold up very well as visual winter interest in the garden. They held up all last winter in my urban backyard, visible against the snow from my kitchen window.
They are unfazed by extended periods of dry weather and their foliage remains intensely green and lush through the summer.
A native species that hosts nitrogen fixing bacteria in their root system, these are worth considering for anyone who is looking for non-invasive additions to food forest and permaculture plantings.
I’ve heard that some gardeners find these to be excessively abundant in their self-seeding, but I haven’t found that to be the case in my gardens, so I suspect that the underlying issue is actually too much open space in the garden, rather than too many seeds from these plants. If you are really worried, you could collect the seed pods once they dry in the fall and offer them to a local native seed exchange since these seem to be in fairly high demand.
