It's Time to Order Compost and Mulch
It’s mid-August, which means that between harvesting and processing, gardeners also need to be thinking about the transition to fall. That includes two important steps: top dressing with compost and mulch. There are factors to consider in terms of both the compost and mulch you choose, but the overarching message is the same: It’s time to figure out where your compost and mulch is going to come from.
Why your garden needs compost
Two things happen in your garden beds over the summer. First, you lose nutrients in the soil, as they are absorbed by the plants growing in the beds. You want to try to return nutrients to the soil, resulting in a nice balance of nitrogen, phosphorus, and potassium. Compost accomplishes that. Second, you lose volume of soil in your beds for a few reasons. When you shovel new soil into your bed, it’s nice a fluffy; but over time, it becomes compacted by watering and gravity. Also, when you take plants out of the bed, you inevitably take some soil with you on the roots of the plant (so you should be sure to really shake those plants out as much as possible). And lastly, erosion happens even in your backyard garden. In any case, you want to top up your beds at the end of the season, and compost is a good way to do it, since you’re getting the nutrition and volume to solve both problems.
Where to get compost
In the most ideal world, you can make the compost yourself by combining green materials like grass clippings with brown materials like cardboard or twigs. These heat up, break down and create a nutritionally rich substance that looks and acts like soil. You can do this in composting bins, try vermicomposting or do it the lazy way. The problem is, you’re probably going to need more compost than you can make yourself, which means you’ll need to source some more.
A hidden trick many people aren’t aware of is that your city may make compost and give it away, or sell it for cheap. If you live someplace where the city collects leaves, they may give the compost away. You can usually find out by Googling the name of your city and “free compost.” Don’t let the cost of compost determine the quality in your mind. I determined after many tests that my city’s leaf compost was far more effective than the expensive organic compost that was four times more expensive.
Be cautious if using manure
Manure from animals is often a component in commercial compost, and farmers are usually willing to give it away for cheap or free on Craigslist for you to use as compost. It might seem like a great idea because manure is, in fact, full of nutrients, but there are some concerns worth addressing. First: There is “cold” and “hot” manure. While you can put cold manure in your beds immediately and it won’t burn your plants, doing the same with hot manure will be toxic for your plants, having the opposite of intended effect. Hot manure (from cows, horses, chickens) must compost on its own before being applied, and it’s not a matter of how much time the manure has sat, but how much it has broken down. Also consider that since those animals aren’t in your care, you don’t know what they ate. If the grass they foraged on was treated with chemicals, there’s good chance those chemicals won’t have broken down and will be introduced to your plants. A few years ago, we had a big problem in Portland, where I live, with organic compost containing herbicide compounds, which killed tender vegetable starts. Even when you have cold compost (rabbits and ducks are a good source), you want to understand what the animals ate, and apply it carefully at first to see if there’s going to be a problem. You can let cold manure compost, too, to allow it to break down.
Mulch reduces erosion, deters weeds, and keeps the soil warm
Once you’ve top-dressed all your beds with compost, you should consider mulch. I think mulch is highly underutilized as a way to keep plant roots cozy in the face of freezes and heat domes alike. Mulch is insulation, which means that you can save on water costs by preventing moisture loss through the topsoil, it protects plants from some of freezing temperatures, and it works to keep the soil at a more stable temperature and moisture level than without mulch. But mulch can do a lot more—it deters weeds by smothering them, and it reduces erosion by working like a blanket on top of your soil. If you intend to plant over fall/winter, no problem: Move the mulch aside and then plant.
Where to get mulch
For most of my life, “mulch” was a homogenous product blown into your yard or bought in bags from Home Depot, and I was always deeply disappointed by the cost and lack of longevity of the product. To achieve any result, you want a few inches of mulch on top of all your beds, and ideally it would be a product that will add to the overall health of your beds. Leaves make great mulch, and if you blow them into your beds in fall instead of bagging them to be taken away, you get insulation, the compost when they deteriorate in place, and you give the bugs that live in the leaves a place to safely chill during the winter. You can also use straw (not hay), but I think wood chips have become so easy to obtain—and often for free—that it is what I recommend. I use wood chips for walkways, for my raised beds, and for the flower beds to give them insulation year-round. Over time, the wood chips break down and become rich compost as well, giving the soil underneath terrific structure, mycelium, and nutrients.
Where to source free chips
There are three ways to get wood chips. The first is to ring up your local rock yard or landscape product center, and ask about them. There is a cost for the chips, and also delivery, and usually the delivery charge is steep (enough so that I always rented a U-Haul trailer for $20 and moved it myself). You can also call local tree-trimming companies and get on a list for a drop-off, which shouldn’t cost anything, but can take a while.
Finally, there is ChipDrop. Reviews on ChipDrop, which allows you to sign up for a free drop of chips most places in the country, are mixed, but I’ve used it all over the country and have been pleased. (Full disclosure: I've been using it long enough I'm in the commercial and now know the founders.) You can exclude types of trees (I request “only hardwood”). Some tips I’ve learned using ChipDrop over the years: You will get a call from the arborist dropping your load off about six minutes before they do so. Answer the phone, and ask what is in the drop. You can always say “no, thank you.” Take a clear photo of where you want the drop for the ChipDrop app so the driver doesn’t have to guess, because they won’t come back and move it. Lastly, understand you are getting a variable amount of chips, but it can be as much as 15-20 cubic yards, which is a lot. Still—it’s free.
By ordering these products now, you can ensure you have it before there’s a run in fall, and you can slowly begin applying the compost and mulch as you clear your beds for fall. It also allows the products a little more time to chill out and compost so that they’re not as hot when you apply them.