I have used pine bark as a mulch and to improve tilth in both my zone 5 and zone 7 gardens. If I could not find aged pine bark, I would purchase the smallest particles I could find of pine bark mulch and set it aside for at least 6 months or prepare new beds well in advance as newly ground pine bark will be "hot" and require a lot of nitrogen when added to new beds as an additive. I would instead make new beds in the fall and let the mixture "cook" all winter before planting any plants after the bark had aged and partially decomposed using alfalfa as my nitrogen source. The best way to make a new bed would be to put layers of newspaper on top of your grass and layer on pine bark, compost, ground leaves, alfalfa, and native soil to at level of 12 inches and just let it cook for 6 months....the grass and newspaper will disappear, the area will settle, and you'll have a nice raised bed for spring planting.
Obtaining pine bark in recent years has been a problem even living in the heart of where they manufacture pine bark mulch. I live just around the corner from a sawmill where I have obtained pine bark in past years and can no longer get it because they are grinding the whole tree now and the product includes the cellulose, the center part of the tree, as well as recycled pine such as chipped up old pallets. Those are the "long" pieces in your newly labeled mulch and the label on your bagged product has been changed from "pine BARK mulch" to "pine mulch" to reflect this change. Pine mulch containing the whole tree and recycled products do not make good additions to your garden....they will change your Ph and attract termites. There is an additional problem in the Carolinas with borers that have been drilling into loblolly pines....they kill the tree quite quickly....yet the dead trees are taken away and ground into mulch. That may be why you can no longer find pine mulch in Canada. Another product that can improve tilth is spaghnam peat which is readily available for use in the creation of new beds. The only problem with peat is that it decomposes quickly whereas pine bark will keep your soil crumbly for several years. Daylily roots LOVE traveling in looser soil and it also makes digging daylilies and cleaning them so much easier. I dig frequently, so using pine bark as a summer mulch enables me to age it "in place" on top of the soil and automatically dig it in with my fall shipments every time I dig up a plant.
I can still find pine BARK mulch here in North Carolina but I have to look hard to find a product that is 100% bark. The products in the big box stores contain the whole tree and shredded pallets so I go to landscaping firms that work directly with the sawmills that still produce a pure BARK product. For bagged products, I prefer the products that are sold as soil conditioners now because they are not only aged, but also 100% bark.....and have, hopefully, gotten hot enough to kill all the buggy things that abound in the Carolinas. These products do not significantly change soil Ph.
Judy
