View Full Version : Wood-chip mulch

09-04-2010, 10:55 AM
Some time back a posting implied there are problems using wood chips as mulch. Can someone explain what these problems are?

(Not talking bagged commercial mulch like pine-bark, but chips from brush, after letting the pile sit a year to kill most seeds.)


09-04-2010, 11:46 AM
Yes, this is true. Here is the explanation: Wood chips (especially fresh chips) are especially high in carbon content. "Good" soil is a balanced blend of Carbon and Nitrogen ......along with a host of other goodies too. When wood chips alone are applied to a soil, as it decomposes, it tends to suck the nitrogen out of the existing soil thus depleting the area of nitrogen.

Even chips that have been sitting around in a pile for a year are not that great. The don't get much moisture or air, components that are critical for effective decomposition.

Moreover, wood chips from tree companies or municipal sources are typically very large, this to tends to delay decomposition.

Yes, good mulch is typically somewhat decomposed.

As for killing seeds. It takes A LOT of heat to kill seeds. Wood chip piles lack a good supply of N to develop a good heat up to kill seeds. Seeds can last for years and years and years under all sorts of wide, varied and adverse conditions.

What will happen if you apply bulky wood chips around plants/ shrubs? Your plants will yellow out due to the lack of N in the soil. They may become susceptible to fungus and disease and just lack any kind of robustness.

There ya go- :waving:

09-04-2010, 02:13 PM

Not to argue but to understand, you indicate the more decomposed the better. But once decomposed, does not mulch (or the former mulch) lose its mulch attributes?

Is it recommended to give plants extra N fert before applying wood mulch?

09-04-2010, 07:38 PM
Excellent question. Yes, I usually add some 12-12-12 before I mulch. Yes, good mulch should be well shredded or at least partially decomposed.