Honey bee forage: black locust

The black locust tree, Robinia pseudoacacia, is famous for producing a fruity and fragrant honey that ranges from water white to lemon yellow to yellowish green. A batch of monofloral black locust honey with little cross-contamination from other flowers can be as clear as a glass jar. The honey is high in fructose so it can be stored for long periods without crystallizing.

The black locust tree is native to eastern and southeastern North America, but has spread throughout the United States and much of Canada. A member of the Fabaceae (pea family), the tree has nodules of nitrogen-fixing bacteria on its roots which make it an excellent species for re-vegetating poor or damaged soils. In addition, its tolerance for low pH has made the tree useful for strip-mine reclamation sites.

Black locust grows quickly and averages 40-70 feet tall at maturity. It is often planted as a source of firewood, not only because of its fast growth but because the wood burns very hot. Although the tree does not tolerate shade or extreme cold, it grows well in a variety of moisture, fertility, and slope conditions.

Although it is considered a major honey plant in the eastern U.S., the black locust does not always produce a crop of honey. Nectar flow is very dependent on local weather conditions and some years the flowers yield little or no nectar at all. Some areas of the country report good crops once in every five years, but the frequency varies with the location.

Even when the flow is good, the flowering period is short. The flowers, which bloom in long, white racemes, open sometime between April and June for about ten days. During the rest of the year the trees are excellent habitat for invertebrates, birds, bats and other small mammals.

Nancy, a reader from Shady Grove Farm in Kentucky, has been enticing me with delectable descriptions of her current black locust flow. Below is a photo she sent of a tree in full bloom.

A final note: The black locust should not be confused with the honey locust, Gleditsia triacanthos. Ironically, the honey locust produces very little—if any—honey. The tree was nicknamed “honey locust” because of the sweet pulp which was used for food by some of the North American tribes.

Rusty
HoneyBeeSuite

Black locust tree at Shady Grove Farm, Kentucky.
Black locust tree at Shady Grove Farm, Kentucky.

Comments

Bruce
Reply

Our community garden is situated on what was previously a salt water drainage area and later the Vancouver city dump. It was capped with a thick layer of clay for use as a city works yard and twenty five years ago was turned into a community garden by a few guerrilla gardeners. Black Locusts were planted for their nitrogen fixing qualities and the fact that they will basically grow in cement. We cursed the Black Locusts for years because of their wheelbarrow tire popping thorns and invasive nature. This changed when we started beekeeping and found that the white blossoms are a favourite of the bees in July for several weeks. We no longer curse the Black Locust trees.

Judith
Reply

We are eagerly awaiting the black locust bloom here on the northeast coast. Another nice fact about this tree is that, in the early 1600s, it was the first tree species to be exported from North America to Europe, and continues to provide nectar for the plentiful ‘acacia’ honey found all over Europe.

Bruce
Reply

This year I met a beekeeper from Eastern Europe who said the Black Locust is popular there specifically for the wonderful honey its nectar produces.

Che Guebee Apiary
Reply

Bruce, that is true :) Black Locust is called Bagrem in the ex Yugoslavia region. The Bagrem honey is the most popular down there. I actually collected seeds from a black locust in the nearby park (Sweden) and intend to grow it. This how-to page is of great help. I notice that Siberian peashrub and black locust seeds are prepared in the same manner. I have both! Happy days for the bees!

Bruce
Reply

I collected some of my Black Locust seeds and dug out some seedlings this week for a beekeeping friend. More happy bees.

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