Applying mulch and wood chips

(Question)

When is the best time to apply the mulch we received from the city recently? We also have wood chips from our cottage in Haliburton. We also have hydrangeas.
Thank You

(Answer)

Mulch is any material organic or not, placed over the surface of the soil to prevent erosion, conserve moisture, suppress weeds and modify soil temperatures.

The time of mulch application depends on what you hope to achieve by mulching. Mulches, by providing an insulating barrier between the soil and the air, moderates the soil temperature. As a result, soil that is mulched in the summer will be cooler than unmulched soil; whereas soil that is mulched in the winter may not freeze as deeply. It is also important to note that since mulch acts as an insulating layer, mulched soils tend to warm up more slowly in the spring.

Mulch used to help moderate winter temperatures can be applied late in the fall after the ground has frozen but before the coldest temperatures arrive.

How thick you apply the mulch depends on the size of the particles. Thin, fine particles like compost or finely shredded bark are best laid 5-7cm deep. On the other hand, if the particle size of your mulch is larger as is the case for pine needles, or chunks of bark, they can be applied 10cm deep. This is because the larger spaces between the chunks of bark allow more air and light in, so you need a thicker layer for effective weed control, water conservation, and protection from the cold.

It is important to note when applying any kind of mulch you must be careful to leave 2.5 to 5.1 cm of breathing room near the stem or base of the plant. If you pile any kind of mulch up against the plant base or on the crown, you will rot the plant and it will die.

Finally you may be interested in the following articles:

https://pubs.ext.vt.edu/426/426-724/426-724_pdf.pdf

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/az/home/?cid=nrcs143_023585