When using wood from a dead tree for the fireplace, make sure it's seasoned. Seasoned wood is dried to 20-25 percent moisture content; fresh wood contains up to 80 percent moisture. (Chicago Botanic Garden)

I have a couple of large trees (oak and white ash) to remove in my garden this year and was wondering if I can use the wood for an indoor fireplace. When is a good time to do this removal work?

Winter is a good time to remove large trees, as well as do some pruning, as there will be less impact on the garden since the ground is frozen and perennials are dormant. Perennials right next to the stump may get damaged when the stump is ground out.

If you plan to plant perennials or small shrubs in the same spot as the stump, ask the vendor to grind the stump extra deep. Remove the resulting wood chips and replace with garden soil when the weather permits. Dig the whole stump out if you want to plant a replacement tree in the exact same spot. Otherwise, shift the new tree over a bit to save on digging the stump out. Another thing to consider is the increase in sunlight once the trees are removed. Some of the existing garden plants may need to be moved to a shadier spot in the garden, while others that were struggling in the shade may perform considerably better with the additional sun.

Your white ash was likely killed by an insect called the emerald ash borer that has decimated the ash tree population in the Chicago region over the last few years, with white ash (Fraxinus americana) being the last to go. Very few ashes will survive the damage caused by this insect unless the tree is being treated with an insecticide. It is best to remove the dead ash tree in your garden this winter as the potential for falling limbs increases quickly for ash trees once they die.

You will be able to use the wood from dead ashes in your fireplace, but do not transport the ash logs out of Illinois. Let your arborist know that you would like the logs cut into firewood length. Consider renting a log splitter if there is a large volume of wood to split.

The most important thing to remember when burning this wood is to make sure it’s properly seasoned before using it in the fireplace to minimize the buildup of creosote in the chimney. Creosote is a highly combustible substance that condenses in liquid form as wood exhaust. It cools in the chimney and then solidifies as it dries. It can build up when you use wood that is unseasoned or wet. Properly seasoned wood produces the most heat and the least amount of creosote.

Freshly cut wood contains up to 80 percent moisture and needs to be seasoned — that is, dried to 20-25 percent moisture content — before burning indoors. Wood containing more than 25 percent moisture is considered green and should never be burned in an indoor fireplace or wood stove. (Be sure to have your chimney professionally cleaned on a regular basis when using a fireplace or wood stove.)

Season the wood you generate from the removed trees by cutting up the logs and splitting them into fireplace-sized pieces that can be stacked out of the rain for at least nine months. Since your trees are already dead, the curing process will have already started, and the wood should be dry enough to burn in a shorter time period. Hardwoods like oak will burn better if seasoned for more than a year. The best wood is typically seasoned for two to three years but will start to deteriorate after four to five years and will not be good to burn. Stack the wood off of the ground and in a way that allows air to circulate and carry away the moisture as it evaporates through both ends of each piece. Protect the woodpile from the rain but try to avoid completely covering it with plastic tarps as air circulation is necessary for proper seasoning. Seasoned wood has a dark or gray appearance when compared with green wood.

Tim Johnson is director of horticulture for the Chicago Botanic Garden in Glencoe.

[  Related: Itching for spring flowers? Here's a trick to force cut branches to bloom now ]

[  Propagating a Norfolk Island pine is tricky. Here's how to try it. ]

[  When do your shrubs bloom? Find out before you prune ]