A minimum of three months under ideal conditions and normally 6 to 9 months is required to properly dry wood. In addition to being unsafe because of creosote build-up, green wood is also inefficient since the fire has to burn off all the moisture before the wood itself can ignite. If you purchase wood, remember that seasoned wood doesn't necessarily mean it is dry. Water moves very slowly out of wood that hasn't been cut to length and split and air dried for several months. Generally firewood quality depends on the type of wood or species, the moisture content or dryness, and its size.
Hardwoods are the trees that have broad leaves, while softwoods are the needled or conifer trees.
For example, poplar is a hardwood, but its wood is softer than red pine, which is called a softwood. All woods burn, but some burn better than others. Amongst the best of our local wood varieties are apple, beech, cherry, maple, and oak, which all produce excellent coals. Some other woods that produce good coals are ash, birch, elm, and tamarack. The easiest woods to ignite are birch, cedar, hemlock, pine, spruce, and tamarack.