Hi Sharon, Yes, this information applies to stem-nesting bees globally. About 30% of solitary bees nest above ground, and those are the bees that you are supporting by leaving stems standing. Leaf-cutter bees (Megachile), small carpenter bees (Ceratina), resin bees (Heriades), and masked bees (Hylaeus) are just some of the bees that will nest in stems in your garden.

Hi Cathy, In general, you can distinguish year 1 and year 2 stems by how worn they are. Year one stems will have gone through an extra winter and therefore be a lot more tattered. You should cut the stems back to between 6-18” tall. Hope this helps!

Thank you! A question: Will it work to cut the stems down to the ground in the winter but prop the cut stems up somewhere as if they’re still on the plant?

Noted! I think we can make that happen.

Hi Trecia, thanks for the idea. We don’t currently have a pdf, but we might be able to make one.

Yes, you can cut back sunflower stalks just like the other plants.

I am not sure about zinnias specifically, but here’s how you can find out: after frost, cut zinnia stems according to the instructions in the blog post. If they are hollow, there’s a good chance bees will use them.

So glad you like our post, and thanks for all that you do to save native bees.

Yes, that’s correct! They particularly like the pithy stems of staghorn sumac for nesting.

Great question! The key part is that the open stem is exposed, but making a clean cut helps bees make a tight cap on the nest after it’s complete. Breaking stems with hands, as opposed to sharp shears, can also compromise the integrity of the nesting site, e.g. cracking/damaging stem. If you are making a cut on a stem on a woody plant, a clean cut also prevents the plant from getting infections.

That’s a good way of differentiating between different generations of stems–i.e. those produced in 2021 vs. 2022. You will want to leave each generation of stems standing for at least 2 years, and *not* cut them to different heights after the initial cutting.

Hi Nan, I am not aware of any resource listing hollow/pithy stems, though the ones I list in the article are a good starting place. Ultimately, it comes from experience–cut a stem from each plant in your garden and take notes! I don’t believe that Jerusalem artichokes are hollow stems–it will be very obvious. The bee larvae will not be free living in the stem. All of them be in distinct cells, wrapped either in mud, leaves, fuzzy plant hairs, flower petals, or sap/resin.

Coneflower stems *are* suitable for cavity-nesting bees. The seeds might be gone, even if the spiky seed head remains. Nevertheless, shake the seed heads in your garden in spring and you’ll have more coneflowers next year!

Here’s a nice resource if you’re not aware of it: https://xerces.org/sites/default/files/publications/18-014.pdf

Hi Elina,

Thanks for your comment! March is a rule of thumb to wait until spring–definitely leave your stems if the birds are still eating the seeds 🙂 The bees that will use your stems largely emerge by late-April, so you can leave them until then.

In the case of herbaceous perennials (those that die back each year/don’t make perennial woody stems), you can leave your stems standing indefinitely. This year, new fresh green joe pye weed stems will grow from the root stock.

Hope this clarifies things!

I am not aware of whether bees will nest in Chrysanthemum stems, but if you have other stems in the garden that are hollow, I think it’s okay if you cut the Chrysanthemums back.

Simply leaving your stems is fine, but bees require an opening in the stem in order to nest in it. Some of the stems in your garden might have been broken by ice and snow over the winter, but many of them might still lack an opening. By making clean cuts on your stems, you will definitely create many more nesting cavities for native bees.

Hello Bob! Yes–you can often tell if a bee has used a stem by whether or not the stem is plugged. For example, leaf-cutter bees (Megachile spp.) will plug with leaves whereas mason bees (Osmia spp.) will plug with mud. Keep in mind that bees are not the only insects that use cavities for nesting. Gentle solitary wasps like Isodontia spp. will readily use stems for nesting and they plug their cavities with grass and plant fibers. Hope you find some occupied cavities this year!

Hello Joe! Our native carpenter bees are important pollinators, and only one species is a nuisance–eastern Carpenter bees (Xylocopa virginica). They do not nest in woody stems in the garden. The carpenter bees that nest in your garden are small carpenter bees (Ceratina) and they are *much* smaller and easily overlooked.

The bigger, more conspicuous eastern carpenter bees will excavate nests in decks, eaves, siding. They are also important pollinators and players in our local ecosystems, and they are super gentle. To deter them from nesting in future years, however, you can cover up the hole with steel wool or caulk the entrance and paint over it. Absolutely please refrain from spraying chemicals.

Thank you Juliette! That’s great work on your part. Some of the weaker stems definitely don’t stay standing. Native bees definitely prefer stems that are standing. Ones that I’ve found to be particularly sturdy are wild bergamot, swamp milkweed, and mountain mint !

Glad to hear that you solved your wasp problem in an environmentally friendly way!

In general, no. Stems on the ground rot much more easily than standing stems.

In the wild, carpenter bees (Xylocopa) nest in dead trees/snags in fields and along wooded edges. The issue is that many untreated decks are perceived in the same way as dead trees to carpenter bees. You can discourage carpenter bees from nesting in your deck by plugging their entrance with steel wool/caulk or painting over the deck to make it less desirable to chew through.