Compost Questions

Q. Mike: It is my understanding that it is permissible and sometimes advantageous to include ashes in a compost pile, especially if one's soil tends to be acidic (we haven't yet tested ours). But my wife thinks it would not be a good idea for me to put any wood ashes on her compost pile. Can you give us some guidelines? Thanks.

---David in Joplin, MO

A. David: I don't know how long you've been married, but sooner or later (depending on the processing speed of your 'upstairs computer' and/or the comfort level of your garage) you will learn that you cannot 'win' an argument with your spouse. Especially if you happen to be right. All you wind up 'winning' is a chilly dinner, a chillier bed, and 'the look' all winter long. And if you make too big a deal out of it, even a Missouri winter can last until July.

But luckily you are not right, so you can simply say, "yes dear" and "you were right dear" (the only two phrases a husband needs to know) and go back to having a happy life instead of the one you would have had were you correct. You are right about wood ashes being a great cure for acidic soil—but not via the compost pile.   

Wood ashes are so strongly alkaline that it doesn't take a lot to upset the balance in a pile and stop the composting process cold. You can add a very small amount—wood ashes are rich in the essential plant nutrients phosphorus and potassium—but no more than about a cup of ashes per sixty four cubic feet of raw ingredients (the standard 4 x 4x 4 foot pile). If you burn wood for heat, that ain't gonna make much of a dent in your ash can.

So get that soil test done. Or even better, several tests: One for your lawn, another for your veggie garden, and one for the rest of your landscape. Most states offer very inexpensive soil tests thru their local county extension offices; Missouri's is just $10. You can also buy devices or test strips that just reveal your soil's pH--or cut to the chase and buy your own soil test kit and go nuts testing everything in sight. (Hey, Honey--c'mere a minute!)

If those tests indicate that your soil IS too acidic for what you're growing (or trying to grow), you can use wood ashes to raise the pH pretty much exactly the way other people use lime. Your local extension agent will be able to tell you exactly how much ash to use in a given area to bring the number up to the desired level.

Oh, and this advice applies only to ashes from a wood stove—do NOT put ashes from a charcoal grill, burned trash or other potentially toxic source into your compost pile. And never ever EVER burn pressure treated wood or old railroad ties for ANY reason.

Q. Mike: We have two compost piles composed of just fall leaves (we have lots of trees). We filled three trashcans this weekend with pulled weeds, and I hate the idea of sending them to the landfill (we need the room for disposable diapers!) but I don't want to 'contaminate' our good compost. Would it be a good idea to create a third pile for 'weeds only'? And should we then notuse the resulting compost in our garden?

---Glenn from Wayne, PA

A. A third pile is a fine idea, Glenn!  As is a sixth, seventh and eighth—you can never have enough black gold! But as we explained in a previous thrilling episode on this subject a few weeks ago, you can't compost weeds—or any other 'wet green' stuff—alone. Compost is made by mixing small amounts of wet green material in with lots of dry browns, of which shredded fall leaves are the finest such thing. So a big 'no' to that potential pile of Weedies.

But incorporate those weeds into your compost you should! Weeds—especially grassy ones—are MUCH higher in nitrogen than the kitchen garbage people put in their piles, and a combination of shredded leaves and chopped-up weeds will create a very high-quality compost. As with leaves, chop or shred the weeds into pieces as small as practical, and then mix everything up well—about four parts shredded leaves to one part chopped weeds by volume.

Worries about weed seeds surviving the process tend to be overblown, but go ahead and over-blow, because it gives you an excuse to put chimneys in the centers of your compost piles. These rolled tubes of animal fencing extending above the top of your raw ingredients will draw in lots of extra air, heating things up to the 160° that insures any weed seeds are incinerated. You'll find all the details in last year's "Basic Compost Making" Question of the Week (see below).

Q. Mike: My husband has two rabbits in hutches lined with cedar or wood chips to catch their "poop"(for lack of a better term). Every week he cleans out the hutches and throws away large bags full of this mixture. I was wondering if that stuff might instead make good compost. If so, please tell me how. Thanks!!!

---Tanya in Wilmington, Delaware

A. Thank you, Tanya—it's a great question! (And feel free to say 'poop' on my show anytime—it drives my poor, long-suffering producer absolutely crazy.)

Anyway, you are correct (another wife who's right—what a shock!): That mixture will make a fine fertilizer—one of the best, in fact. Manure from small herbivores like rabbits, hamsters and gerbils is very high in nitrogen, and will create super-premium compost when combined with dry brown materials like those wood chips. You can just pile it all up by itself or incorporate it into a pile containing other raw materials. But see if your hubbie will consider switching to a less 'dense' bedding material, like wood shavings or shredded fall leaves. Wood chips can take quite a while to break down.

And as we always like to remind people, this is just for herbivores—animals that eat plants, like the little guys we mentioned, and big ones like horses and cows. Never put dog or cat poop into a compost pile—it simply isn't safe.

For more info (and the answers to the questions you're thinking of right now), see these previous compost-oriented Question of the Week