What? Leave Stem Stubble in Our Gardens??
We gardeners and landscapers are being asked to rethink what our gardens can contribute to increasing and returning biodiversity to our landscapes. Who knew how much it matters to our insect pollinators to leave stem stubble in our gardens year-round to provide nesting habitat and winter shelter!
Heather Holm, biologist, award-winning author and pollinator conservationist in Minnesota, helped create this graphic below to explain how this works. Now when I clean my gardens in the spring, I cut the pithy or hollow stalks back to 8-24” tall, and break the rest up into pieces, leaving them around the plants as their own mulch, helping them recycle their nutrients naturally.
Heather shared these close-up photos of cavity nesting bees so we can see what could happen when we leave stem stubble (and rotting logs and branches). Below is a photo of a small carpenter bee working on its nest in a pithy stem.
And below, is a cross section of a mason bee nest in old wood. It’s fascinating to think of all the work involved: mining out the pith, collecting the pollen(larval food), laying the egg, fabricating a wall and repeating the process in that nondescript dead stalk!!
Let’s leave them some stem stubble!!