Hello Fellow Readers,
Springtime is mulch time and John from Andover NJ asked what kind of mulch is best. First and foremost, remember to apply only two to three inches of mulch and stay clear of trunks and stems to prevent disease (a polite way of saying no volcano mulch).
There’s a trend in using cocoa mulch which can be toxic to pets and the sweet smell can attract wild animals, so best to stay clear. Then there’s the controversial dyed mulch often made from recycled wood products such as wood pallets, old decks and other construction debris that can be contaminated with harmful chemicals. Plus, the impact of the dye itself covering up the mystery of the wood products used. Hence dyed mulch is another stay-away as far as I’m concerned to keep plants healthy.
I prefer cedar and hemlock mulch which have fewer mold spores as compared to other hardwood mulches and doesn’t break down as quickly. But is there a risk of spreading Hemlock Woolly Adelgid (HWA) by using hemlock mulch? Hemlocks infected with HWA have what looks like a white powder on the foliage from the tiny insects that feed on the twigs at the base of the needles. It once devastated hemlocks, though the problem has greatly improved, and thankfully hemlocks are readily used in the landscape once again.
According to the University of Massachusetts (UMass Center for Agriculture) who works in cooperation with the US Department of Agriculture, “given that hemlock bark mulch is made from the bark of the trunk and major branches, there should be limited or no adelgids present in those areas.” They go on to say, “bark mulch should not be used as soon as it is made, for a variety of reasons other than the HWA. If six months have passed from the time of manufacture, then a very limited movement of the adelgid would be expected onto another host.” Bottom line, hemlock mulch is safe and favorable to use.
What about using the wood chips galore from the cleanup of the downed trees. Nature relies on decomposing limbs, trees, and leaves to build rich soil. However, woody materials are high in carbon and cellulose and need nitrogen and time to decompose, temporarily depleting nitrogen from the soil. Therefore, I wouldn’t suggest mixing fresh wood chips directly on your soil. But if you combine wood chips with a high-nitrogen organic material such as dried blood or fish meal they can be tilled into the top layer of the soil and will provide nutrients rather quickly.
Some say wood chips mulched around trees or shrubs is perfectly fine. They believe any nitrogen hindrance that might occur is limited to the soil surface and has virtually no negative impact on plants with deeper root systems. I don’t know, fresh wood chips around plants remind me of a garden under a drive-through menu. A step above tomato sauce red mulch, but not so pretty. Better to use wood chips to create a woodland path, a cushion under a play-set, or as paths between raised beds in your vegetable garden. Garden Dilemmas? Askmarystone@gmail.com