Should I Put Coffee Grounds in a Worm Bin?

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First off, in my post on using coffee grounds in your garden I linked to the wrong article. The correct, and very useful publication by Linda Chalker-Scott, “Using Coffee Grounds in Gardens and Landscapes” can be found here.

There were a number of questions and emails about the pamphlet’s recommendation not to add coffee grounds to your worm bin. Why might coffee grounds not be good for worms? Chalker-Scott cites a study, “Evaluation of three composting systems for the management of spent coffee grounds” that looked at using worms to compost coffee waste. The study showed high worm fatality in spent coffee grounds due, the authors speculate, to the acidic pH of coffee and harmful organic compounds. The addition of cardboard reduced fatality. They go on to suggest pre-composting coffee grounds for three weeks before adding to a vermicomposting bin.

It should be noted that the study was looking at worm bins where the feedstock was entirely made up of spent coffee grounds. Adding a few coffee grounds to a home bin made up of a diversity of feedstocks is probably not going to kill the worms.

But, in a discussion thread on the Garden Professor’s Facebook group speculating about what percentage of coffee grounds would be safe to use, I found myself agreeing with Raymond Eckhart who says,

In the absence of peer reviewed literature as to what percentage is acceptable, the cautious approach is to avoid it altogether, is my takeaway. If and when someone studies the issue to determine a safe percentage, it would be unwise to recommend the practice, given the results of the referenced paper.

Coffee grounds also form large anaerobic clumps worms don’t like. Clearly, they prefer vegetable scraps and large amounts of fluffy carbon material like cardboard and wood shavings.

Now wouldn’t it be great if Elon Musk would fund local Extension Service home gardening research rather than trying to figure out ways to blast rich people into space? We need definitive worm bin advice!

Islamic Geometric Patterns

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I’m making an effort (not always successful) to avoid falling down the Google/Facebook/Youtube hole vortex in the evening. The siren song of internet distraction rarely leads anywhere useful and I’ve never regretted turning the damn thing off and taking up pencil and paper.

Through some library serendipity, I discovered Islamic Geometric Patterns by Eric Broug. It’s a book of step by step drawing instructions. All you need is a ruler, compass, pencil and pen. While the geometry behind theses patterns is enormously sophisticated, actually drawing out the shapes is surprisingly easy and relaxing. It’s also a fun and painless lesson in geometry, especially for those of us not inclined towards math.

The first chapter breaks down the basis of all the patterns–squares, hexagons and pentagons–and how to generate these shapes with just a compass and ruler. Here’s the square and hexagon:

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Starting with these basic shapes, you then do further subdivisions. Once the pattern is penciled out you start using ink to make the final design. Add color and texture and these basic patterns can become enormously complex, what David Wade calls “windows into the infinite”:

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So what can you do with this arcane exercise in geometry? Just look at some of the amazing things Broug has done with these patterns on his website. I’m particularly fond of simple applications for patterns such as the way he painted his garage door. If only my school geometry was as much fun as spending an evening drawing these patterns.

Weekend Tweets: Poppies, Insane Comics and Black Metal Cats

Meet the Solavore Sport Solar Oven

IMG_7172 (1)As we mentioned a couple of weeks ago, the good folks at Solavore have loaned us a solar oven to play with this summer. We’re still working on how to cook in the thing–more on that later–but we thought we’d take a moment to show you the oven itself.

The basics:

This is a Solavore Sport, which sells from their website for $229.00 US, plus $39.50 for the optional reflector. (We’d recommend the reflector, unless you live near the equator, or only plan to use your oven at midday in high summer.)

Solavore is a woman-run company, based in Minnesota, and the ovens are made the U.S. Plus, Solavore partners with NGOs to bring sun ovens to sun-rich, fuel-poor developing countries.

Solavore keeps an extensive, and attractive recipe section on their site.

The oven itself:

The floor of the oven measures 9 1/4 inches x 17 1/2.

It weighs 9 pounds.

It is entirely made of plastic. The body is all black molded insulated plastic, while the lid is double-walled clear plastic, molded to fit the oven body.  There seems to be a trade off going on here between portability (and perhaps lower shipping costs) and structure. They opted for it not to have a heavy casing.

It doesn’t seem flimsy by any means, but at the same time you can imagine doing it some serious damage if you were to trip over it. I worry particularly about cracking the lid around the thin edges. Yet at the same time, I really appreciate the portability. I love how light and easy the Sport is to manipulate. It is simply no big thing to move it around, and until you get the hang of solar cooking, and learn the way the light moves in your yard, you’re going to be moving it a lot. It’s light weight makes it good for camping and picnicking, too.

IMG_7224The oven is made to hold two cooking pots at a time, which is handy, because you can do a main dish and a side at once, or a pot of something for dinner and a pot of something for lunch.The Solavore comes equipped with two shiny new black Speckleware casserole pots for this purpose, though you may choose to use any pot you like–though lightweight black pots like the Speckleware are best for solar cooking. It’s also big enough hold a casserole dish or a quarter sheet pan.

The Solavore also comes with a free standing thermometer which you can use to monitor the internal temperature of the oven.

We don’t have experience with any other commercial sun oven by which to compare the Solavore Sport, so all we can say so far is that it totally works. It’s been getting to cooking temperature easily (200-250F), even though the sun is still a little low in the sky at this time of year, as long as you follow the directions and use it correctly.

IMG_7174Quibble with the clips

So far we have no complaints at all, and only one quibble: the clips.

The lightweight lid must be clipped down to the oven body to maintain proper heat efficiency. Having failed to read the starting instructions properly (ahem), I missed that detail on our first trial, and had trouble getting the oven up to cooking temp–which lead to a lentil disaster.

I failed to notice the lid clips were there at all first time out because they are not immediately obvious. They are small metal hooks which are permanently affixed through holes in the oven’s body. They come up over the lip of the lid to hold it down tight.

The good thing about these clips is that they are very simple and would be easy to replace with a piece of wire if you break them. Also, since the clips are tied to the oven, they can’t be lost, which is another major advantage.

The downside is that they are finicky to use. I have a hard time getting them over the lip of the lid, and always feel like I’m in danger of abrading or even cracking the edge of the lid as I force them on and off. Each time I  wrestle with them, I dream of a quick release system, or wish I could just use binder clips to clamp the lid to the body–but regular clips don’t work because of the particular shape of the lid/body interface.

But all in all, that is, as I say, only a quibble.  We’re enjoying playing with the oven, although as I alluded to in my last post on the subject, there is a learning curve to solar cooking. We’ve had a few disasters, which we’ll talk about, but we’re beginning to get a good feel for what works well in this cooking system. More to come soon!

083 Kris De Decker of Low Tech Magazine

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Our guest this week is journalist Kris De Decker, the creator of Low Tech Magazine, a blog published in English, Dutch and Spanish that covers low tech solutions in great depth and detail. Without exaggeration, I think it’s safe to say it’s my favorite blog. On the podcast we discuss high tech problems, Catalan vaulting, fruit walls, Chinese wheelbarrows, open modular hardware, fireless cookers and alternate forms of the internet.

If you want to leave a question for the Root Simple Podcast please call (213) 537-2591 or send an email to [email protected]. You can subscribe to our podcast in the iTunes store and on Stitcher. The theme music is by Dr. Frankenstein. A downloadable version of this podcast is here.