Cat Litter Compost, Installment #3


No, our cats aren’t privileged or anything.

A gentle reader reminds us that it’s been too long since we updated you all on the cat litter compost.

For background, see Installment One and Installment Two

Long story short, cat litter composting can work (under the care of an experienced composter, mind), especially in conjunction with a worm bin–but I’ve found a method I like better.

On the composting experiment:

In our last episode of Cat Box Madness, I discovered my kitty litter wasn’t breaking down very quickly, so I added nitrogen to the mix. That seemed to work well. All except the first 7 inches or so is really nicely broken down all the way through. I still wouldn’t put it as it is anywhere near food crops, even though it is two years old, just to be safe.

To make it extra safe — and useful — I’ve been letting the worms have at it. I’m using it as part of the mix that forms the worm bedding, so cat poo will become worm poo and the garden will be delighted.

That’s how I plan to dispose of all of it, bit by bit. If I didn’t have the worm bin, I’d call it done and spread it under fruit trees or ornamental plantings.

Lessons Learned:

1) Make sure your pile is accessible and easy to turn. Due to lack of yard space, I put my litter in a 50 gallon drum in a narrow, hard-to-access–and hot!–side yard. This meant I never wanted to tend it, and when I forced myself out there, I was pretty unhappy. There wasn’t even enough room to wield a shovel comfortably.

2) A big pile is a good pile. While I made this work in a 50 gallon drum, the best compost comes from a bin which is about 1 cubic meter/yard in size. Smaller bins just don’t heat up sufficiently, and are invariably pokey and hard to work with. If you want to do this, do it big.

3) Careful with the litter you choose. Not many litters make the grade. You can’t use clay litter, or any litter made with deodorants or coloring or “magic crystals” or tiny unicorns. It must be made of 100% plant based material. I approve of both World’s Best and S’wheat Scoop. Pine pellet litter, like Feline Pine, is much less expensive than the clumping brands, and suitably plant based, but under ordinary circumstances, since its not scoopable, you have to dump the whole tray rather often, which leads to a fast build up of material. If you have room for it, this might be okay.  (I’ll have more to say about pine litter further down, though.)

4) You have to add extra nitrogen to your pile to make it work. Even though it’s plenty stinky, the nitrogen present in cat waste can’t balance the heavy carbon loads of the litter by itself.

(Note: You should be an experienced composter before you try composting cat litter, as I’ve warned before, and so you will of course know what I mean by all this talk of carbon and nitrogen–but for those of you who are incorrigible, or simply curious, nitrogen sources you might add to your pile include urine, natural seed meal fertilizers, dried alfalfa, fresh grass clippings and other plant material, fresh chicken, horse, or cow manure, and vegetable trimmings.)

Other than those caveats, cat litter composting works pretty much like regular composting. Keep the pile moist. Keep an eye on it, fix it as necessary. Let it sit for two years at least before you spread it. And then spread it around non-edible plants, or under fruit trees. The fruit trees won’t uptake anything nasty.

It’s totally do-able and I’d do it again. But I’d rather do it again in a larger yard, where I could have a big, accessible compost bin. So now I’m doing something new.

Continue reading…

Maintaining a Worm Bin

worm bin 1

This image might represent a new low in aesthetics from the Root Simple Photo Department. And that’s saying something.

I freshened up our big worm bin today and I thought I’d report on what I did because I get a lot of questions about worm bin maintenance.

First, I want to say this is just how I go about it. Other people will have different methods and habits. Worms are forgiving and reasonably adaptable, so you have a whole lot of leeway in keeping a bin. As long as you don’t let the worms dehydrate, drown, bake, or utterly starve, you’re going to be okay.

Our worm bin is pretty big (5 feet long), and made of pine boards.  It bears an unfortunate resemblance to a coffin, but it works wonderfully. I used plastic storage totes for my worm bins before we built this, and while those worked fine, I really like my big bin for two main reasons. The first is the size. It can take whatever I throw at it. It takes all my kitchen scraps, except for the really choice stuff that goes to the chickens. The second selling point is that the wood breathes, and that seems to make the worms happy.

Maintaining the Bin

The Conceptual Divide

I divide my bin into two areas, left and right. There’s no physical barrier between the sides, just a conceptual distinction. Usually one side is working and the other side is resting. This division is easy to make in a long, skinny bin like mine, but can be managed in a smaller bin as well.

Basically, once you’ve got a worm bin going, there will come a time when you’ll need to harvest some of the castings. Those castings are valuable in the garden, and the worms don’t want to live in their own waste. You’ll know its getting close to harvest time when you see pockets of scraps here and there, but mostly the texture of the contents looks like soil or coffee grounds. Or maybe fudge, if it’s more wet and compact. Fudge is a less than ideal environment for worms.

In the picture at the top you’ll see my most recent working side. There’s a lot going on in there still, some big food pockets, wood shavings everywhere, but the texture is becoming too black and dense overall. Compost worms like a little air, a little “wiggle room” and a diversity of habitat. It was past time to change this working side to a resting side.

Resting comes before harvest. This is where dividing the bin in two comes into play. Resting means no more feeding, so that the worms will finish up whatever bits of food are left around. But of course you can’t starve out your worms, so you only rest half of the bin at a time.  To do this, you put your food scraps on one side only. The worms on the resting side will finish up whatever food pockets remain and then migrate over to the active side for the fresh grub.

This doesn’t happen quickly. I’ve never made note of how long migration takes–it will vary, depending on many factors. I just poke around in the resting side whenever I happen to think about it. If I don’t see anything recognizable beyond non-digestibles, like avocado pits, fruit stones and egg shell shards, and I know it’s ready for harvest.

There will also be a few worms left, no matter how long you wait. More on them later. If your bin is outdoors, other insects like sow bugs might be in there too, but are harmless.

This is the process in a nutshell:

When your bin is looking mostly done, ie full of castings, rest one side of it. This means you feed only on the opposite side. When all the recognizable scraps are gone from the resting side, you harvest the castings. Then you can put fresh bedding in the empty space, and start encouraging the worms to move to that side.  Soon, you will be able to rest the opposite side of the bin, and eventually harvest it. And so it goes, back and forth.

Continue reading…

The tale of the worm bin celery

parsley flower

This is related to my recent post about our flowering radish. It’s a tale of botanic dumpster diving and another reason why you should let your food plants go to flower when you can.

Last year I threw the crown (which is to say, the bottom) of a celery plant in my worm bin. I probably should have chopped it up for the worms’ sake, but I didn’t. Later, sometime in the fall,  I rediscovered the celery crown. Instead of rotting in the bin, it had sprouted leaves and looked surprisingly vigorous. So I pulled it out and popped it into an empty space in one of our raised beds.

I didn’t have much hope. Celery doesn’t like our climate much, and I consider it one of those plants which is easier to buy than to grow.

To my surprise, the plant did quite well, though it did have a feral quality to it, despite its mild domestic origins. It didn’t grow fat, moist stalks which can be used to scoop up peanut butter. It grew stringy, dark green stalks which tasted powerfully of celery. It made excellent stock, and chopped into fine pieces, it was good in soup, too. Since I don’t eat much raw celery, this suited me fine.

All winter long I used this plant as the basis of my cold-weather cooking–chopped onions, carrots and celery in the bottom of every pot. It was a real treat not to have to buy celery for such a long time, and to have that flavor available whenever I wanted it. I should add that the leaves were just as flavorful as the stalks

As a side note, I’ve heard of a breed of celery made to work precisely this way, called cutting celery, but I’ve never grown it intentionally. The celery in this post looks very much like my homegrown “cutting celery.” Perhaps commercial celery wants to revert to this?

Months later, the hot weather arrived, the celery started to bolt (that is, send up flower stalks). When a plant bolts, it puts all its energy into flowering. At that point, its not much use to us as food. I was sad to lose my bottomless celery supply, but I was excited about the flowers.

Pollinating insects love celery blossoms. Actually, they adore the whole family of plants to which celery belongs, called Apiaceae or Umbelliferae (which I tend to call Umbrella Fae, which is wrong, but right in my head). This family includes carrots, celery, dill, coriander, fennel, Queen Anne’s lace, etc. If you can let any of this family bloom in your garden, do.

The parsley flowers grew almost as tall as me, and they were surrounded by clouds of tiny insects every day –shy, tiny little pollinators that I can’t name.

I love to let things go to flower and seed in the garden, because it is a way of giving back to the rest of nature. Flowers for the insects, seeds for birds. And by giving back, you help balance your garden. We’ve had significantly less issues with destructive insects since we learned to let our garden go a little wild.

Sadly, this celery never got to seed, because it collapsed under its own weight one day. Its thick, hollow stalks folded and the head of the plant fell to the patio.  I had hoped to save a little seed and try to grow a plant the next year from scratch. But now I’m thinking I’m going to throw a whole crown of celery in the worm bin this fall, and hope this happens all over again.

collapsed parsley plant

Black Widow or False Black Widow?

some kind of widow spider

I have a family of widow-type spiders living in my outdoor worm bin. I like spiders and all they do around the garden, and have a no kill policy toward them in general. This particular situation, however, has had me a teeny bit nervous. They hang out on the underside of the lid of the worm bin for the most part, though I’ve seen them on the surface of the worm compost once or twice. Obviously my concern is that I will touch one when opening or closing the bin, or while burying my kitchen waste.

Believing these spiders to be black widows, my options have been either to be very attentive while around the worm bin–or to roll out the vacuum. So far I’ve opted for being careful.

The thing about these spiders is that they lack the identifying spots on their abdomens, but I remembered being told somewhere that not all types show the red marks, and that males never do. Was this true? Were there other types of spiders that looked like this? After weeks of tip-toeing around the worm bin, I finally got around to doing some research. My conclusions are not conclusive, so I’m coming to you, dear readers, for help.

Wikipedia’s entry confuses me a bit:

Not all adult black widows exhibit the red hourglass on the ventrum underside or top of the abdomen — some may have a pair of red spots or have no marking at all. Female black widows often exhibit various red markings on the dorsal or top side of the abdomen, commonly two red spots. However, black widow young are believed to have at least some sort of marking on their abdomens. Adult male black widows are half the size of the females, and are usually gray or brown rather than black and red; while they may sometimes have an hourglass marking on their ventral abdomen, it is usually yellow or white, not red. Variation in specifics by species and by gender is great; any spider exhibiting a red hourglass or a pair of large red round spots on the ventral abdomen with an otherwise black shiny body is an adult female black widow.

Here is how I read this: Not all adults display an hourglass…but females often display some sort of red mark. Young and males may or may not have some kind of mark, but not red…but be careful! Variations by species and gender are significant. If you see a black spider with red markings, be very, very afraid. That there is definitely a female black widow. But really, there’s no guarantees here that other less flashy spiders aren’t some kind of dangerous, either.

This is not reassuring.

But then on the handy page Frequently Encountered Spiders in California, I learned about the False black widow.

Another European invasive, this spider seems to be displacing our native black widows in urban areas.  This spider is roughly the same size and shape as a black widow, but is brown with a faint purple sheen.

I like this false black widow option a lot. The false widows don’t have a dangerous sting.

The spiders in my box are pretty shy, but insofar as I can tell, they are all sort of an eggplant color–not that true, bad-ass black of a classic widow. Nor have I seen any red marks. (That doesn’t mean that big mama with her red marks isn’t hiding somewhere.)

So, from this not-so-great photo, can anyone tell me if this particular spider might be a false widow, Steatoda grossa, or a male black widow, Latrodectus hesperus? It’s about 1/2 inch in size.

UPDATE 5/10:  After reviewing the evidence, I believe this is a false black widow. However, my trouble are not over, because it turns out that they do have a venomous bite, apparently somewhat like a mild black widow bite. Here’s the bite intensity scoop according to UC IPM: black widows: obviously bad; brown widows: mild; false black widows: moderate.

What’s in Worm Leachate?


Garden Professor Jeff Gillman analyzed worm leachate (the liquids the flow our of your worm bin) from a home vemicompost setup. It’s pretty strong stuff! Gillman concludes,

this could be a great liquid fertilizer if it were used properly.  I’d recommend diluting it somewhere between 1:1 and 1:5 worm juice : water before applying it, and I’d only apply it once every week or two.  If you want to use it, try it on something that you’re not too concerned about first, just to make sure that it doesn’t do anything too terrible (It shouldn’t, but I believe in caution).

To see a full analysis, read his post here.