Black Locust Flowers are Here!

Black Locust Flowers are here! That means it’s time to plant last year’s seed! Today we’ll look at identifying Black Locust flowers, as well as some different ways to plant Black Locust seeds to grow happy new trees!

You might be asking, why should I care about identifying Black Locust flowers? The answer is because you can eat them, and they are incredibly delicious! The bees also love Black Locust flowers, and make incredibly delicious honey from their nectar.

Imagine a floral sugar snap pea dipped in honey; that’s what Black Locust Flowers taste like! And it’s no surprise either, as Black Locusts and peas are in the same family, Fabaceae. Black Locusts are basically gigantic pea trees! And the flowers of Black Locust look just like the flowers of snap peas and string beans, but in long clusters or bunches like grapes. Check out the picture below to see what we mean.

And like peas, Black Locusts are nitrogen fixing, meaning they build fertility into the soil. It just keeps getting better!

But wait! There's more!

Black Locust wood is also incredibly dense and one of the most rot-resistant woods you can find, and it has the heat value of anthracite coal, making it a highly valuable fuel. Plus, it grows incredibly quickly!

While we obviously love Black Locust, and think you should too, some people don’t, and it’s a bit of a controversy. You can read more about that on our Black Locust Profile.

So now that we understand why we want to grow Black Locust, let’s learn how.

Each of those flowers that you see will become a pod full of multiple seeds (well, the ones that you don’t eat at least 😜). When those pods dry out in the fall and the seeds harden, they are ready to be harvested. See the picture below.

These seeds can be stored in a cool, dry place like a cellar or basement and will remain viable for many years. Once the flowers appear on the trees again in the spring, it’s time to plant!

But Black Locust seeds won’t just germinate all on their own if you stick them in the ground and water them. At least, not this year. You see, in order to protect the unborn tree, Black Locusts put an incredibly hard seed coat around the seed, making water unable to penetrate. This seed coat has to be broken in order for moisture to enter and wake up the seed.

In the wild, this breaking of the seed coat, called scarification, happens after multiple years worth of freeze/thaw cycles, disturbances like fires, or when the seed pods get eaten by a mammal and pass through their digestive tract. Quick side note on that, Black Locust foliage is an incredibly nutritious and high-protein forage for ruminant mammals like cows and sheep, and make a great addition to a silvopasture system!

But, of course, we don’t want to wait five years for the seeds to germinate, so instead we actively break the seed coat. There are multiple ways to do this, and we tried out a few to see which is the most efficient and effective for our particular operation. 

The three methods we’re testing are hot water bath, mechanical scarifying, and fire.

For the hot water bath, we brought a pot of water to a boil and turned off the heat. We let the water cool for just a minute or two, and then dumped the seeds in. Then we let them soak in the warm water overnight and planted them out the next day. You can clearly see the difference that the hot water makes, as the treated seeds (bottom) are swollen with moisture and are a lighter color than the untreated seeds on the top. Akiva at Twisted Tree Nursery has a great video on this method on his YouTube channel.

The next method we did was mechanical scarification. Basically, we held the seeds in a pair of needle-nose pliers and ran them across a sheet of sandpaper until we could see the seed within the hard seed coat. The seed is a light yellow and is clearly visible in contrast to the seed coat, so it’s easy to tell when you’ve made it through. Once they were scarred, we soaked them in lukewarm water for a few hours to let them swell up before planting.

The last method is likely to be our favorite, as long as it works out well. For this method, we left the seeds in the pods, rather than winnowing them like we did for the other methods, and then made a pile of the dried seed pods and set it on fire. Andy noticed once that in the wake of an old burn pile at Hawk Meadow Farm, hundreds of little Locust seedlings had sprouted up. This was an attempt to emulate that, and the process of wildfires that break Black Locust dormancy in the wild. There were lots of popping sounds during the fire, kind of like popcorn, so if this doesn’t work, then next year we might try burying the seed pods under an inch or two of soil and then building a small fire on top of them. That way the flames aren’t directly on the seeds, but the heat is still enough to break the seed coat. We shall see! 🤷 

We’ll keep you posted on how the seedlings are doing throughout the year, and we’ll be sure to let you know when they are available for you to buy!

In the meantime, get out there and go eat some Black Locust flowers!