Container gardening for pollinators

In the city, outdoor gardening space can be hard to find. Backyards are replaced by balconies, but this doesn’t mean you can’t still garden for pollinators. You just have to get creative about it. This National Pollinator Week, TPI has tips and tricks for how you can support urban pollinators with container gardening whatever your outdoor space looks like (even if it’s just a windowsill!).

1. Choose perennial native plants. Apart from a few species with deep taproots, many native plants will thrive in containers. Since they’re perennial, your plants will come back year after year, and support pollinators without any extra cost. Here are some good options that TPI has had success with:

  • swamp milkweed (Asclepias incarnata)
  • anise hyssop (Agastache foeniculum)
  • lance-leaf coreopsis (Coreopsis lanceolata)
  • smooth aster (Symphyotrichum laeve)
  • great blue lobelia (Lobelia siphilitica)
  • cardinal flower (Lobelia cardinalis)
  • blazing star (Liatris spicata)
  • virginia mountain mint (Pycnanthemum virginianum)
  • purple coneflower (Echinaecea purpurea)
Blazing star (Liatris spicata), aka gayfeather, is a favorite of pollinators and easily grown in a container! PC: Flickr, CC.

2. Combine plants with complementary bloom times to have the greatest impact. For your first container, try picking three plants: one that blooms in early summer, one in mid-summer, and one in fall.

3. Deep containers are your friend. Choose containers at least 16” deep to allow your native plants to build strong root systems and thrive for years to come.

4. If you only have space for shallow planters (<12” deep), annual or biennial native plants are a great option. These plants don’t invest in a deep root system and can survive in shallower soils. Black-eyed susan (Rudbeckia hirta), spotted horsemint (Monarda punctata), and partridge pea (Chamaecrista fasciculata) are three good choices.

5. Flowering herbs are also a great (and tasty) option for small spaces. TPI previously waxed the benefits of letting your herbs for pollinators, and the same applies here. Dill, lavender, thyme, mint, and cilantro are all popular herbs that do well in containers and favorites of pollinators.

Container herb gardens can be a win-win! Flowering mint feeds all sorts of pollinators, like this metallic green sweat bee (Agapostemon sp.), and you can enjoy mint leaves in sun tea and watermelon coolers! PC: Nick Dorian.

6. Water often. Soil in containers dries out faster than those growing below ground, and as your plants become root bound, they will need water more frequently. As always, water the soil rather than the leaves.

7. Don’t fertilize. Native plants are adapted to soils that are low in nutrients, and adding fertilizer will result in many big leaves and not many flowers. Amend store-bought potting mix with perlite and sand to create a well draining medium for your plants. Leave the manure and kelp fertilizer for your veggies!

8. Protect your container plants over the winter with 3-4” of leaf mulch, by moving your planter to a less exposed area, and potentially covering with a tarp. The key is to keep the soil warm enough so the roots don’t freeze through.

What pollinators live in the city?

Have you ever wondered what kinds of pollinators like to visit urban gardens? My work this summer can help answer that question! My name is Maria Ostapovich, and I am currently a first year Master’s student at Tufts and a new member of TPI. Since the beginning of July, I have been surveying pollinators in gardens around Somerville, MA to understand 1) which pollinators occur in urban gardens and 2) which flowering plants those pollinators depend on. I surveyed pollinator-friendly gardens and ornamental gardens to see how they compared to one another.

Me surveying the ornamental garden in Powderhouse Square rotary. PC: Nick Dorian

Surprisingly, it was difficult to find public gardens (within walking distance) to survey during this project. The eight suitable gardens I found seemed like unlikely homes for pollinators: a busy bike path, a yard next to a construction site, and the middle of a rotary. But after my first survey, the opposite proved true. In the middle of the city, flowers everywhere were brimming with pollinating bees, wasps, hover flies, and butterflies.

Twice per week, I surveyed all eight gardens on foot. I made sure to pack plenty of water and wear comfortable shoes for my trek through Somerville and, by the end of each six-hour survey, I had invariably logged 10,000 steps. At each garden, I identified each flowering species of plant and counted the number of blooms. Then, I identified and counted the number of pollinator species that visited flowers, noting which species of plant they visited over 10 minutes.

First, I found that not all plants are equally attractive to pollinators. Commonly planted ornamental plants like day lilies and hostas did receive some insect visits, but native plants consistently outshone them. The white candelabras of culver’s root were particularly attractive to pollinators in June and July; cutleaf coneflower was a favorite of sweat bees and long-horned bees; and goldenrod stole the show in the fall. Native plants, clearly, were a favorite of pollinators in Somerville.

Bees love asters! Metallic green sweat bee (Agapostemon sp.), sweat bee (Halictus sp.), and the common eastern bumblebee (Bombus impatiens) on New England aster in a pollinator-friendly garden. PC: Maria Ostapovich

Overall, the insect diversity that I observed was incredible. I found insects ranging from fuzzy, clumsy bumblebees to indecisive, metallic green sweat bees. I observed cute little leaf-cutter bees holding their abdomens aloft and I saw formidable (yet harmless!) great black digger wasps. Among many other pollinators, I saw long-horned bees quickly zipping between flowers and several convincing bee-mimics including a hover fly (Spilomyia longicornis) that looks nearly identical to a European paper wasp. Surprisingly, I observed few butterflies during my surveys, perhaps a result of unfavorable conditions earlier in the year.

Male long-horned bee (Melissodes sp.) taking a break on a sunflower before zipping off. PC: Nick Dorian

I learned so much this summer, most notably how to identify urban plants and pollinators! For any tips for identifying pollinators on your own, check out TPI’s identification guides. While it was fun to learn how to identify so many species, it was even more exciting to see what kinds of plant-pollinator interactions took place across these gardens. Although the data analysis is still ongoing, I will be able to generate lists of plants that pollinators like and dislike as well as document the weeks of the year during which plants are flowering and pollinator species are most active. These findings will be coming soon after I complete my surveys (which are continuing until frost reaches Somerville) and after I learn the best way to analyze my data. Make sure to keep an eye out for additional blog posts sharing more of my findings!

To learn more about our ongoing efforts to document urban pollinator biodiversity, get in touch with us through social media or!

Help TPI find bumble bee colonies!

While you’ve been hunkered down at home, have you seen any bumble bees in your urban yard? Maybe you’ve even seen a bumble bee nest! We want your help in scouting out the bumble bee nests of the urban greater Boston area.

TPI scientists have been hard at work trying to learn about the nesting ecology of bumble bees (Bombus spp). Bumble bee nests are the focal point of reproduction. In early spring, the queen emerges and forages alone for pollen and nectar. Then, she produces workers which take on foraging tasks, and the colony grows exponentially. Late in the season, as the colony begins to senesce, males and new queens are produced. After mating, males die and queens overwinter underground to start the cycle over.

Bumble bee reproduction cycle
Bumble bee life cycle. Image credit: Jeremy Hemberger

We have learned a great deal about bumble bee nesting in natural areas, but now it’s time to take that work into the city. Preliminary results already suggest that bumble bee reproductive ecology may differ between natural and urban environments, and we want to explore this further. Bumble bee nests can be difficult to find, but that’s where YOU come in.

Do you think you’ve seen a bumble bee nest? We want to see it! Bumble bees are cavity nesters, meaning they nest in small openings, such as crevices in rock walls beneath garden sheds. If you see frequent traffic of worker bumble bees (~1 bee/minute) to and from a single location, chances are you found a colony! 

Bumble bees nesting in an old bird house. Image credit: Kstevens01, Flickr

If you think you have a bumble bee nest in your yard, or know of one in the greater Boston area (within 15 miles of the Tufts Medford-Somerville campus), take a photo and get in touch with us by filling out this survey.

Thank you in advance and we look forward to hearing from you!