My home gardens are all in the shade, so this is based on my experience in our Pollinator and Rain Gardens here at Behnke Nurseries. These six are favorites for multiple reasons: from ease of growing, to attractiveness for both people and pollinators. And these are daytime, 9 to 5 pollinators. Goodness knows what the nocturnal visitors (if any) think about my selections. Below are all native to Maryland, unless noted.
There are two species commonly grown as garden subjects, Asclepias tuberosa, the Butterfly Milkweed, and Asclepias incarnata, the Swamp Milkweed. Tuberosa had a better agent when it came to common names. Butterfly Milkweed has brilliantly orange flowers on knee-high plants that are the focal point of the garden when they bloom in late spring to mid-summer. (Blooming varies some with the weather and the individual plant, figure four to six weeks of bloom.) Besides the flowers, milkweeds have those wonderful parachutes that carry the seeds in the wind. As kids we called them fairy wishes. Butterfly milkweed must be planted in well-drained soil or they will rot off; in the wild they often grow in sandy locations. They are one of the last perennials to emerge from the ground in the spring, the leaves first appearing in late April or even early May.
The swamp milkweed is taller, chest high, with either white or pink waxy flowers. They are found in marshy areas, moist ditches, and so on, but adapt quite well to garden soil. They start blooming a little later than the butterfly milkweed. A drawback to both milkweeds is aphids. You are certain to get infestations of orange aphids on the stems, and they can be unsightly. You can keep the numbers down with an occasional blast of water from the hose. Milkweeds are the only food source for monarch butterfly caterpillars, so be prepared to have some of your leaves eaten, if you are lucky!!
Golden flowers in late summer bloom at the same time as ragweed. Ragweed has low-key flowers, is wind pollinated, and causes a lot of allergy misery, and goldenrod gets the blame because it’s easier to see as your eyes are tearing and you’re sneezing. There are many species and varieties. My favorite is ‘Fireworks,’ which has cascading flowers on four foot plants; it’s just a spectacular plant in bloom. We also have planted ‘Solar Cascade’, which may be mislabeled as it doesn’t quite behave as described. It is supposed to be a shorter version of ‘Fireworks,’ but in our bed (which is not typical garden soil, it’s very organic) it’s about four feet tall. The drawback to goldenrods is that they spread quickly with underground stems. These two still spread much more slowly, and unless you are planting a meadow, you want this.
Mountain Mint (Pycnanthemum)
There are several species of mountain mint, we have Pycnanthemum muticum planted out. It has teeny white flowers surrounded by small gray bracts (modified leaves), sort of like a poinsettia has small golden flowers surrounded by red bracts. It flowers for most of the summer, and it seems to always be covered with bees and butterflies. Mountain mint is tough. In the sun and good soil we have, it is dense, the flowers completely covering the top of the four foot stems. It spreads aggressively, and we have to thin the edges several times a year. I’ve seen it living in shade on a mountainside in North Carolina and bone dry under trees at the edge of a parking lot in Potomac. Not thriving, but surviving, and the deer seem to leave it alone. I’m trying it this year at my place in the shade of a beech tree. When it got a foot tall I cut off the top 4 inches to make it fuller and keep it shorter. We’ll see.
Joe-Pye Weed (Eupatorium or Eutotrichum)
The Joe-Pye Weeds are swallowtail butterfly magnets. With a long blooming period from mid-to late summer, they bloom in various shades of pink. We grow E. dubium ‘Little Joe,’ which is a short form, getting about 5 feet tall in our garden. Others, like E. maculatum ‘Gateway’ might reach 8 feet or more, so they aren’t for the faint of heart. They do best in full sun but will take some afternoon shade. I see them growing in moist ditches at the edge of the woods. They like moisture, but do fine in average garden conditions. This may also require some thinning, but is not as aggressive as the mountain mint. It also produces a lot of seed and you can expect seedlings of various heights to appear. This is a plant that often looks bad in a pot, but thrives once it’s in the ground.
Aromatic Aster (Aster oblongifolius or Symphyotrichum oblongifolium)
Like the Joe Pye weeds, the botanists have reclassified the Aster genus and split it up into a series of new scientific names that a) better recognize relationships in what was a large group of plants and that b) that I am too old to remember; or even care about, truth be told. Luckily, we still have “aster” as the common name. This particular aster is very late blooming, with pretty blue flowers. A USDA scientist who was shopping at the garden center said it was particularly useful due to the late bloom (late September into as late as early November) to provide a food source for a late season butterflies, or migrating butterflies. There are a couple of common cultivars, ‘Raydons Favorite’ and ‘October Skies’, the latter said to be a little shorter. They both sort of sprawl. We have ‘October Skies’ planted out, and it gets about two feet tall at the center, cascading out to the side. They do well in normal to drier garden soil.
Anise Hyssop (Agastache)
Not native to our area. Most of them come from the North American west, and are prissy about drainage, seldom surviving the winter. There are hybrids with an Asian species, and these are much tougher. These hybrids have blue flowers, and we have one of the older varieties, ‘Blue Fortune,’ planted out. It makes a dense clump about 5 feet tall, blooming all summer, and is always covered with pollinating insects. The foliage has a nice anise scent, and our clump has made it into year three with no effort on our part. I cut some back hard in mid-summer, and they grew back to about 18 inches and began to bloom again. As with the mountain mint, you should be able to cut this back when about a foot tall to about half that height early in the season to keep it shorter than 5 feet, and still get good blooming. If you want to know more about this technique, buy The Well-Tended Perennial Garden by Tracy DiSabato Aust; a perennial gardening classic.
A note on pollinators. Many pollinators are of the bee and wasp persuasion. I find that they are so engrossed in their business that they pretty much ignore my presence in the gardens, as long as you move slowly and deliberately and don’t do anything stupid, like grab one by mistake. I am allergic to wasp stings and carry an Epipen. Although I spend most of my time in the office these days, I have only been stung twice in my forty year nursery career, both times by accidentally grabbing a bee on a plant in a pot. I’ve yet to need to use the Epipen, knock on wood.