We are smack in the middle of the "Ides of March" and spring is tantalizingly within our reach. It's been a year since we starting becoming aware of how the coronavirus pandemic was going to affect our lives. It's also that time of the year when we start sowing many of our food plant and annual flower seeds. This year more than ever, I'm determined to experience the wonder of growing human and bee food from seed.
But first, we prune! Garden wisdom says it's time to prune the roses when the forsythia is blooming. It's that time of the year to get plants in the rose family in tune for spring. I head out to my garden on a sunny day with leather gloves and pruning shears to tackle the invasive blackberry that took advantage of the warm winter, and clean up the canes in my raspberries that bore fruit last year. (The ones I missed last fall.) Now there are tiny carpenter bees that nest in the stems of the rose family, so I keep some of the dead stems in my yard in an undisturbed place. The bees can use them once they've dried out. I used to recommend bundling them, but since watching a webinar with a scientist named Colleen Satyshur who specializes in stem nesting bees, I've learned that bundling creates better opportunities for parasitic insects to take advantage, so we don't want that.
Ideally they should be put in a place in your garden that is sheltered from rain and gets morning sun. As for weather they should be vertical or horizontal--experiment! See what the species of bees in your yard prefers. As for those invasive blackberry stems--bees don't generally like to nest in green stems and I have enough other stems to leave for the bees, so these go in the green bin. Some of the raspberry canes I just "crop and drop" at the back of the garden beds. I've also seen these small bees nesting in the stems of salal. Some bees like hollow stems, others prefer pithy stems. Some other plants I've seen bees nesting in include fennel (non-bulbing), bamboo and Joe pye weed. They just need the diameter that suits them and (once cut) the stem itself has to be able to last at least one year so the bees can emerge as adults.
I'm thinking of creating some "stem art" pieces to hang individual stems on my fence to see which bees choose each kind of stem. This way I can keep records and learn as a community scientist what I can recommend to other gardeners. I encourage you to do the same!
For more information, I highly recommend this webinar from the Oregon Bee Project: