To avoid energy costs, some homeowners are turning to wood for heat. Plant species is an important consideration as not all trees have the same density and therefore, heat value. The greater the dry weight, the better.
The highest value for trees commonly found in Kansas is Osage orange (hedgeball tree) at 4,800 pounds per cord. Osage orange has a gnarly growth habit and a nasty set of thorns. This species also sparks which isn’t a problem in a wood-fired boiler but certainly would be in an open fireplace.Black locust is next with 4,200 pounds per cord. Black locust is a fast grower and has excellent burning qualities and makes a nice bed of coals. However, it is hard to split, suckers, and has some small thorns, especially on young trees.
Bur oak and red oak come in at 3,800 and 3,500 pounds per cord respectively but are not fast growers. Mulberry, however, has the same weight as red oak but grows more quickly. Silver maple has less heat value (3,000 pounds per cord) but is a very fast-growing tree.
Black locust is a tempting choice for this purpose due to its heat value and fast growth. However, black locust suckers and is invasive and can spread to areas you don’t want and so be careful if you choose this species. Another species, such as mulberry may work better for you. Or consider planting several different species in rows.
So, how do you set out your plantation? Dr. Wayne Geyer, our late forestry professor, did many woody biomass studies over a period of 35 years. Following are some recommendations that have come out of his studies.
- Plant on a close spacing, 4 to 6 feet apart. This maximizes yield and reduces side branching.
- Control weeds for the first two years.
- Harvest every 5 years though slower growing trees will take longer. Most trees will resprout and can be re-harvested.
- Plant about 1 acre per year for 5 years if you wish to supply most of the firewood needed to heat your home.​
The trees mentioned above and available from the Kansas Forest Service include mulberry, Osage orange, bur oak, red oak, and silver maple.
Lauren Fick is the Horticulture Extension Agent for the Cottonwood Extension District. If you have questions, she can be contacted by e-mail at [email protected] or by phone at 785-628-9430 or 620-793-1910.