Black locust is a fascinating tree. Today I'll share a quick description of black locust trees in general, some pros and cons to consider of their spreading, as well as how I harvest and cook with their delicious white flower clusters that are, without a doubt, the best edible flower I've ever had.
Besides the commonly eaten flowers pictured in this post, bristly locust *(Robinia hispida) are also edible, and pink!
Black Locust Tree Identification
Black locust (Robinia pseudoacacia, also known as false acacia or yellow locust) are often large trees.
Once you get to know them they're easy to spot at a distance with their irregular crowns, and grooved, scaly bark. Young trees often have long, prickly briars on the trunk, as well as smaller ones on the young branches.
During late spring and early summer they can produce incredible amounts of flowers that eventually produce flattened, leguminous pods that look like tiny snow peas. The seeds inside the pod are edible, but tiny and hardly worth gathering in my opinion.
An invasive with potential?
Black locust is seen as an invasive tree or a trash tree in a lot of places, but the tree also has some uses. One thing that's been interesting to read about is the invasive status of black locust in North America.
In most of the states I know It's thought of as invasive, even in it's native range in some places, but I found a useful article by Maureen Sundberg comparing black locust to the American chestnut tree invading maple, ash and birch forests after the glaciers receded.
Sundberg mentions that Although black locust spreads through woods quickly, it also hosts 67 species of Lepidoptera (butterflies and moths). There's a link to the article at the bottom of the post.
Black locust is a fabaceous tree in the legume family, which means that it's a nitrogen fixer, increasing the amount of nitrogen in the soil where it grows. This might sound good, but enriching soils that are low in nitrogen (nitrogen fixing can be helpful in soils not low in nitrogen) can also pave the way for more invasive species to grow in the understory below the trees.
No matter how you look at the tree, it's vigorous growth and root suckering means it has the potential to change landscapes. I'd prefer if the trees stay out of the oak savannahs near me, since if the oaks go, all the wild mushrooms that grow with them will go too.
Black locust wood uses
My lumberjack friend Zach of Foxwalk Sawmill is milling some locust for my deck. I spoke with him about it and was surprised to hear him talk at length about the commercial value of black locust wood. Producers seem scarce, but Zach says he uses a good amount of it, pricing it at a premium comparable to Brazilian hardwoods.
Black locust wood is extremely rot resistant, so Zach uses it as a substitute for treated wood. Cutting black locust down and selling the wood at a high price seems like one of the best uses of an invasive I know of. You can't build a deck from Japanese knotweed!
Finally, the flowers. Black locust blossoms are my all-time favorite edible flower, and if you haven't tried them you're missing out. They're enjoyed and well-known in the wild food community and during late May and June my social media is usually filled with people eating them.
Since they're a legume, the flavor of the flowers is slightly reminiscent of peas, but with an intense, sweet aroma that reminds. The smell of the blossoms is often compared to vanilla, but I think jasmine is more accurate. At peak season I can smell the perfume from a distance before I even reach the tree, and it's intoxicating.
Harvesting Black Locust Flowers
To get the flowers you have to move quickly. I've heard some people say the window for harvesting is up to two weeks, but I disagree. At first glance, some branches full of aromatic white blooms may look good, but if they've been on the tree for too long, the flowers can be dried out and discolored, lacking in flavor and wilted.
You're looking for pristine white flowers with a strong aroma. young, unopened flowers are edible but not ideal. Harvest your flowers on a dry day as rain can compromise them.
Harvesting the flowers is easy. The difficult part is finding low-hanging branches that you can reach. I've found two types of hunting that work well for me. The first is looking for trees on the edges of woods that have low branches. The second, and the most efficient is finding young colonies of trees that aren't much taller than me.
Getting branches that are out of reach
If branches are just out of reach, I'll unravel a coat hanger and use the hook to gently lower the branches. To harvest, I grasp the branch with one hand, and strip the flowers from it with the other. Inevitably you'll get some leaves mixed in, which you'll want to remove as they're not palatable. In a good patch, I can easily harvest multiple gallons of flowers in twenty to thirty minutes.
After I pick them from the tree, I cool down the flowers as fast as possible, storing them in a container with hard sides to prevent them from being crushed. It's ok to harvest them in a paper bag, but you'll want to put them in a plastic container or at least a zip-top bag in the refrigerator to prevent them from drying out.
When you bring the flowers home, spread them out and inspect the blooms before eating for insects. Other than that they don't need any special treatment. There’s no need to wash the flowers, and doing so can waterlog them, robbing them of their sweet nectar and perfume.
Cooking Black Locust Flowers
Most of the time when I see people cooking with black locust flowers it's in the form of flower jelly or deep-fried blossom fritters. To me, both of those are a waste of food. I bread and fry plenty of things, but flowers are delicate and deserve a light touch. It's also hard to make fried batter and sugar taste bad.
Until a few years ago, I mostly used the flowers as a garnish. That changed when Samuel Thayer described a black locust flower recipe to me that was not only delicious, but completely changed how I consider the plants as an ingredient. If you take nothing else from this post, it should be the lesson hidden in Sam's locust salad.
Sam takes a large amount of black locust flowers, cooking about ⅓ of them quickly in coconut oil until wilted. Off the heat, he stirs in another ⅓. After the mixture is cooled, he stirs in more fresh flowers, along with sweet corn.
I've cooked a lot of things, but never in my life had I considered cooking the flowers as a vegetable. The thing is, it actually makes sense to cook them since they're the only flower I know of that can not only be harvested in large quantities, but also tastes mild enough to eat in an amount comparable to another vegetable. It was nothing short of genius.
Besides stuffing your face with handful after handful and upping your salad game, black locust flowers can also be dried for tea and infusions. The dried flowers aren't as intense as fresh, but they can be added to tea blends and make an interesting dessert infused into dairy.