Compost: Can You Buy It in a Bag?

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Question. Mike: Do you happen to know if it's possible to buy good quality compost in bags? I'd like to use compost in my garden, but only seem to be able to find manure and topsoil in bags at the garden center. I've seen places that will deliver loose compost by the cubic yard, but I don't have a driveway for them to dump it. Love your show!

---Peter in Ardmore, PA

Answer. Thanks, Peter! Now if you have access to good quality yard-waste compost in bulk, my first suggestion is to see if it can be delivered to a friend's home nearby or some other mutually agreeable site where several gardeners could share both it and the cost. You'll find lots of info on buying bulk compost in this previous Question of the Week.

Otherwise, the basic answer is yes; there are high quality bagged composts out there. But as with most things gardening, the devil—or angel—is in the details. Here's an updated version of how I addressed this topic in my 2006 book, "Mike McGrath's Book of Compost" (still in print, kids; get your copy today!)

If we're talking about the cheap, wet, heavy, generically bagged stuff without a lot on info on the label sitting out baking in the sun at a big box store, it's not my first choice. (Or second, or third, or…) It shouldn't be anyone's choice, really. The labels and names on cheap bags of "Maybe Compost" are generally somewhere between non-existent, confusing and extremely misleading (as the materials inside the bag often are as well). And this low-rent spread has probably been anaerobic inside that bag for a long time.

If it's all you can find (and it isn't; there's always mail order if you truly live in a horticultural supply desert), two esteemed experts I interviewed for the book, Ohio State University Professor Dr. Dan Herms and University of Maryland Professor Emeritus Dr. Frank Gouin suggest you buy a sample bag, take it home, open it up and give the contents a 'quack' test. (If it looks like good compost, feels like good compost and smells like good compost, it might actually be good compost.)

If it quacks loud enough, go back and get some more, empty the bags out, mix the contents together (ideally with some REAL home-made compost or some of the premium stuff we'll soon mention) and let it sit awhile before you use it.

"Square Foot Garden" author Mel Bartholomew once offered a variation on this method during one of our conversations. He suggested you visit a number of different stores, buy one each of their bagged composts, bring them home and evaluate them. Then go back and buy a couple bags each of the best ones and mix them together—again, ideally with some backyard compost or stuff from a premium bag.

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BUT you should only do this if you have a high level of internal honesty. If anything tends to be 'good enough' because you already bought it or it's all you could find at the very first store you visited (and your idea of 'good compost' includes slimy things that don't stink really bad), forget about it. You might get lucky, but that's what you'd be. In other words, the odds are against you, and if you feel unable to make the decision with any certainty, cut to the chase and search out some high-quality premium bagged compost instead. You and your garden will be MUCH happier.

Some of the brands I've used and been happy with include "Gardener's Gold" from Garden's Alive; "Coast of Maine" (available in larger independent garden centers from at least New England down to the Washington DC area); and "Leaf Gro", packaged by the state of Maryland's superb yard-waste recycling program—something I'd like to see more states imitate.

There are also two 'specialty' bagged composts I've used: "Chesapeake Blue" (composted crab waste and sawdust) and "Chesapeake Green" (composted poultry manure and bedding). Both are rich in Nitrogen; and Chesapeake Blue has the added advantage of being rich in chitin (pronounced "kite-in"), a substance that occurs naturally in seafood shells, survives the composting process and makes the soil it's applied to toxic to destructive nematodes. In the North, bad nematodes generally only attack a few ornamentals, like boxwoods. But down South, root knot nematodes are a destructive pest of MANY plants. Search for chitin-rich composts, my Southern friends, and you will be happy.

(Note: The beneficial nematodes you purchase to control pests like beetle grubs and fleas in the soil are not harmful to plants. But they are nematodes, and so could also be killed by lots of chitin. Just to be safe, avoid seafood composts if you're applying these helpful creatures to your soil.)

There are probably dozens of other high-quality bagged composts available across the country—these things tend to be regionally produced and packaged. But you should know them when you see them. They will cost a little more, have a lot more info on the label and basically give you a warm and fuzzy feeling all over.

One final note (hey—my producer just keeled over laughing; I wonder why?), peat moss is NOT compost. It is a popular component in seed-starting and potting mixes, and a natural antibiotic that prevents damping-off and some other diseases. But it's too light in weight for many applications, contains little to no actual nutrition, and can radically lower the pH of your soil whether you want it to or not. Now don't get me wrong: I like peat moss. I use peat moss. Peat moss is a friend of mine. "But I know compost; and peat moss is NOT compost."

One OTHER final note (oh—THAT's why she keeled over), Dr. Gouin wants to stress that 'dried' products like Milorganite and dehydrated manure are not compost. Composting is a complex process by which raw ingredients are changed by living organisms and processes. Drying is not the same—not even close. Dried something-or-other can't do all the wonderful things that living compost does.

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