Having finally got our hands on both Desmanthus illinoensis and Desmanthus leptolobus seed of decent quality, we’ve recently had our first go at growing them! However, while seeking reliable information on the cultivation of the two species through friends and the web, we realised that there’s not really that much easily-accessible information currently available to the wider public. Further, what practical growing knowledge we have found is largely fragmented throughout obscure research papers, exotic plant fora and other websites.
Accordingly, we’ve put together this brief overview of Desmanthus illinoensis cultivation, compiled from various authoritative sources, combined with our own (admittedly limited) experience of the genus so far. In addition to the method described below, some researchers recommend treating with a suitable Rhizobium inoculant for improved survival rates (one specific reference we’ve seen has been to use “special Desmanthus inoculum strain CB 3126”), although we’ve not yet had a chance to experiment with this technique ourselves. Furthermore, remember that if you’re growing illinoensis outdoors all year-round then you’ll need to be somewhere in USDA Hardiness Zones 5-8.
In summary: We hope this initial draft of our Desmanthus illinoensis cultivation guide will go some way toward setting you on the path to a productive relationship with the Desmanthus genus. As always, if you’ve practical experience of growing Desmanthus illinoensis, or the cultivation of Desmanthus leptolobus, etc. please do get in touch – let’s make this a useful resource for the community at large!
- Coco coir (or similar)
- Desmanthus illinoensis seeds
- Paper towels
- Planting container
- Plastic freezer or sandwich bags
- Water (tap water should be fine)
- Wooden spoon
- Boil a small saucepan of water.
- Turn off the heat source once the water is boiling and allow it to cool to ninety degrees or so before moving on to the next step.
- Pour the Desmanthus illinoensis seeds into the saucepan, stirring rapidly for between five and ten minutes. Be careful – you’re aiming to soften the seed’s hard outer shell, without damaging the seeds!
- When you’ve finished stirring, decant the water and then carefully remove the treated seeds.
- Place the seeds on some moist but not dripping paper towel.
- Carefully move the paper towel with the seeds on into a plastic sandwich bag. Do not seal the bag.
- All being well, the seeds should start to sprout after a few days. Once the majority of the seeds are sprouting, you can sow them into a container of coco coir – lightly bury them just under the soil line.
- Create a humidity chamber by covering the container with a large sandwich or freezer bag.
- Leave the illinoensis somewhere in partial to full sun for a few weeks to form seedlings. Keep the soil moist and don’t forget to cycle in fresh air by removing the plastic bag for fifteen minutes or so every day.
- When their stems show signs of bark development, the young plants can be transplanted to (preferably) the ground or larger containers.
- At this point, the plants will need to be positioned in full sun, and should be watered regularly to maintain adequate moisture levels. Allow the soil to dry out between watering. Nutrient-rich soils are less vital when growing this species, as its roots harbour nitrogen-fixating bacteria, but do leave plenty of space for roots if you’re looking to cultivate healthy, mature plants.
Elena Beyhaut, Becki Tlusty, Peter van Berkum & Peter H. Graham – ‘Rhizobium giardinii is the microsymbient of Illinois bundleflower (Desmanthus illinoensis (Michx.) Macmillan) in Midwestern prairies’
June Latting – ‘The Biology of Desmanthus illinoensis’
Keeper Trout – ‘Trout’s Notes On: The Cultivation of Desmanthus’
Melissa Luckow – ‘Monograph of Desmanthus (Leguminosae–Mimosoideae)’
Ralph W. Keltling – ‘Longevity of Illinois Bundle Flower (Desmanthus illinoensis) Seeds’