Black Walnut Firewood

Every fall when the walnuts start dropping and staining everything they touch, I know it's almost wood-burning season. Black walnut is one of those species that people either love or overlook entirely, woodworkers will practically fight you for the lumber, but for firewood? Most folks have no idea how good it is.

At 20 million BTU per cord, black walnut sits right in the sweet spot of the firewood BTU chart. Not elite-tier heat like hickory or oak, but solidly above average. A cord of dry walnut weighs about 3,230 lbs, which is moderate, heavy enough that you know you're getting real wood, light enough that stacking a cord won't take all weekend. The green weight is 4,584 lbs though, so if you're hauling fresh-cut rounds, plan for some heavy loads.

Splitting black walnut is a pleasure. Seriously. The grain is usually straight, and even large rounds tend to pop clean on the first swing. Low smoke, few sparks, and it throws off a pleasant, mild fragrance, not as sweet as cherry or apple, but definitely noticeable and always a compliment from anyone sitting by the fire. The coal quality is good, not excellent, so walnut is better mixed with something denser for overnight burns rather than being your sole heat source on the coldest nights.

Plan on 12 to 18 months of seasoning time. Walnut holds a lot of moisture when green, we're talking about nearly 1,400 lbs of water weight per cord that needs to evaporate. I've tried to rush it and burned walnut that was only 8 months seasoned... you can tell. It hisses, it smokes more than it should, and you lose a chunk of that 20M BTU potential. A moisture meter takes the guesswork out, anything under 20% and you're good.

Black walnut earns an excellent overall rating and it deserves it. Common throughout the Midwest, Northeast, and Southeast, it's a reliable, well-behaved firewood that splits easy, burns clean, and smells great. If you can get your hands on it, take it. And if you like walnut, butternut is its lighter cousin, less heat but even easier to split.