When you say to mulch shrubs, what is the best type of mulch to use? Can I use last fall’s leaves (mostly oak and maple, not shredded) or does mulch mean pine straw? Or those bags of bark nuggets? What are the advantages and disadvantages for each mulch type?
Lots of materials make good mulches. Any kind of well-decomposed organic matter will work: leaf mold (which is just leaves that have decomposed enough to have a soft, tissue-paper texture and to have broken into small pieces), aged sawdust, aged stable bedding (a combination of straw, or hay, and manure).
When selecting the right mulch, shredded leaves, are a good choice. They tend to stay put when the wind blows because shredding breaks them into small fragments that lock together. Also, they break down fairly fast, releasing nutrients and improving the texture of the soil (earthworms love them, and so do the tiny soil critters and microorganisms that contribute mightily to breaking down organic matter and building soil). Also, the raw materials–that is, fallen leaves–are everywhere and you can gather as much as you need in return for a bit of hard labor. When deciding on what mulch to use, I often ask neighbors if I can have the bags of leaves they put at the curb to go to the dump. Then I take the bags home and dump out the leaves and run the lawnmower over them. (Just take care to keep your feet out of harm’s way.)
Peat moss makes a poor mulch. First, it breaks down very slowly, largely because it has few nutrients and so does not much interest all the decomposers. Second, when it dries out, it tends to shed water instead of absorbing it, which means a rain may run off the garden instead of reaching the ground.
Garden centers sell several kinds of byproduct mulch–shredded bark, shredded bark mixed with shredded wood, and bark nuggets (a cute term for hunks of bark). All work fine. They vary in texture, look, and nutrients. Shredded bark looks the most uniform, breaks down faster, and offers more nutrients. Shredded bark mixed with wood tends to look jagged after a year or so, when the small bark pieces have broken down and only the wood splinters remain. Bark nuiggets break down very slowly, so they last a long time, but they look a bit clunky, though if you never see them from near at hand, they’re fine.
Mulch at the garden center costs dear compared to bulk mulch, which you can sometimes buy from landscape contractors. I’ve also noticed that private composting companies have sprung up here and there and will sell mulch in bulk and deliver it by the truckload at fairly good prices. Finally, many cities compost leaves and give away the compost or sell it cheap. It’s the best deal going, both for mulch and for the health of the soil.