Should we use fresh maple wood chips for garden mulch?

Asked November 19, 2013, 5:11 PM EST

We would like to use the mulch produced when our maple tree was cut down recently. Is it okay to use maple wood mulch on flower gardens? If so, is lime required to cut down acidity in the mulch?

Frederick County Maryland mulch maple trees wood chips

1 Response

Wood chips and sawdust residue from your recently removed maple tree are valuable commodities, but care must be used when you use them as mulch. The main concern is the carbon to nitrogen ratio in the mulch. Raw wood chips and sawdust are extremely carbonaceous, i.e., they contain very little nitrogen. Bacteria insist on being involved in the decomposition process, but they require lots of nitrogen in order to reproduce.

Consequently, if you place raw wood chips around your flowers, the bacteria will rob nitrogen from the soil and the plants which will result in damage or death to the plants.

The best use of your wood chips is to either place them in a pathway or to place them in a pile somewhere and sprinkle a cup or two of nitrogen fertilizer over them. Let them sit for several months until they break down. Do not add lime, since that will actually cause a further loss of nitrogen. Maple chips are not very acidic to begin with, but they will be very close to neutral pH by next summer. You should be able to use them as mulch by mid summer next year when your plants would like to have a light mulch to keep the soil cooler.
LS