Trees for bees
The underappreciated way to help pollinators in your yard
In recent years there has been an increasing awareness of ways that people can support pollinators by better managing their lawns and gardens. Unfortunately, it seems like much of the attention and debate has had a well-meaning but often misguided focus on turfgrass lawns and their associated weeds.
As a bee scientist, I feel like the whole debate about non-native lawn weeds like dandelions actually distracts from much more effective strategies to help pollinators, such as trees for bees. I agree everyone should absolutely stop dumping pesticides and fertilizers on their lawns (and think about ditching their lawn altogether), but when it comes to the sheer amount of resources provided to pollinators in the spring, flowering trees will win out every single time.
When deciding on the best ways to help pollinators, we need strategies that match with our ecology and climate. As has been discussed elsewhere, one of the issues with strategies to help pollinators such as “No Mow May” is that they were originally developed in Europe, so simply adopting them in the United States may not be a perfect fit.
In one informative study, scientists compared the floral ecology of bees in Michigan and England, and they found that there are big differences in the seasonality and ecology of many species. For example, the United States hosts many more species that depend on spring-flowering plants including spring ephemerals and different trees and shrubs. In contrast, they found the English bees they studied were much more generalized and were active the whole season rather than just in spring.
Based on that research, it’s clear that trees for bees can be an effective and ecologically-relevant strategy to help many of our spring-flying bees. With that in mind, I wanted to offer a (non-exhaustive) list that highlights some of my favorite flowering trees for bees, listed in roughly the order that they bloom in spring. These are all trees I observed this spring and it reflects my location in Minnesota, but is applicable for many areas of the northern US that have distinct seasons. It’s also particularly relevant given that a lot of new trees are being planted to replace the ash trees killed by the emerald ash borer.
My favorite trees for bees
When we talk about very early season resource for bees, nothing beats willows (genus Salix). They are some of the earlier blooming flowers, and there are few flowers that bees love more than willows. I wish people would plant more of them, though they can be tricky because most species do best in wetlands. However, prairie willow (Salix humilis) grows in dry soil.
After willows, one of the earliest blooming trees for bees are maples (genus Acer). In the picture below, notice how the maple blossoms are shiny with nectar. If you taste them with the tip of your tongue, they are noticeably sweet. And though they may not look like much, it’s hard to overstate how much bees love these flowers, and you can often see many bees flying up high in maple trees while they are flowering. Also, while native plants are best, bees seem to love all maples, regardless of whether or not they are native (so don’t worry if you already have a Norway maple in your yard, but it’s best to newly plant native species).
One of the all-time best trees for bees is the humble crabapple tree (genus Malus). When these trees bloom, they are a bee magnet, and everything from mining bees to bumblebees love them. They even attract rare bee — for example I saw a Nevada bumblebee visiting a crabapple tree in St. Paul (see picture below) and they aren’t even supposed to occur here. And though crabapples may not taste very good, they still provide a lot of food for birds and other wildlife. So if you want a tree that pollinators will love that wont grow too massive or require too much maintenance, crabapples are always a good choice.
Wild plums (in the genus Prunus) are also beloved by bees. Similar to crabapple trees, you can often find wild plum and cherry trees literally swarming with bees. Don’t worry though — these bees are harmless and are only interested in the flowers and finding mates. It can be quite an experience to go up next to some of these trees — in this case a wild plum tree, and have a cloud of bees flying around your head. See video below:
The many kinds of wild cherry trees (also in the genus Prunus) are another bee favorite, and we have many native species (such as choke cherries and black cherries) that are excellent trees for bees. There are also a number of cultivated varieties that bees also love. Below is a mining bee (genus Andrena) on choke cherry flowers, and you can tell they like them because even when the trees are tiny and tucked away, the bees still find them.
One interesting tree for bees that flies under the radar is Ohio buckeye (Aesculus glabra). Ohio buckeye is a big favorite of many bees, especially bumble bees like the black-and-gold bumblebee (Bombus auricomus). Black-and-gold bumblebees are special because they are the biggest bees in our area. The queens vary quite a bit in size, but the biggest ones are like flying mice and create a loud, noticeable buzz when they fly. However, for all their fearsome size, they are actually an incredible docile bee, and I’ve observed their nests from a few feet away and never been bothered.
Ohio buckeye also highlight one of the big reasons that trees are unappreciated as a supporter of pollinators: it’s hard to see bees when they are so high up or obscured by leaves. For example, this spring I found an endangered rusty-patched bumblebee (Bombus affinis) queen gathering pollen from an Ohio buckeye tree (see picture below). However, she was so high up I could only identify her using binoculars. In most cases, these bees simply go unnoticed, and instead people are often drawn to the handful of bees visiting dandelions at our feet rather than the swarms of bees in the trees.
One of the best things about trees for bees is that even though individual trees don’t bloom for a particularly long time, collectively they provide continuous floral resources. In my area, hawthorns (genus Crataegus) are one of the later-flowering spring blooming trees/shrubs. They are yet another species that often host swarms of happy bees.
Lastly, this has just been a sampling of the great trees for bees, largely focused on my area in Minnesota. There are many great trees and shrubs for bees, including willows (genus Salix), maples (genus Acer), wild cherry and plum (genus Prunus), dogwoods (genus Cornus), crabapples (genus Malus), serviceberry (genus Amelanchier) and hawthorns (genus Crataegus). Edible fruit trees, such as apples, pears, and cherries are also great, though they can take more work to care for. Finally, there are some later blooming trees and shrubs, such as Sumac (genus Rhus) and lindens (genus Tilia) that are also great options. These flowering trees and shrubs offer an invaluable source of pollen and nectar for bees, and most bloom in the early season when many other things aren’t flowering.
Although this certainly isn’t the whole story — many other flowers are important for bees in spring, such as spring ephemerals — trees for bees are an important way to help bees and other pollinators. Plus, planting trees is a great way to help bees if you aren’t able to convert your lawn into a more pollinator-friendly garden. And if you are so inclined, you can add a “soft landing” of native plants for pollinators under your trees.
So the next time you’re thinking about upgrading your yard or lawn, consider a good tree. Native and near-native are best, and there are almost endless great options to choose from. Remember, when you’re planting for pollinators, don’t forget the trees for bees!
