Blue Blade; Destroyer of Favas

Loading the Fava Bean Shredder

This year we are making a more concerted effort to actually, like, plan meals and buy what we need as opposed to ending up with the world’s most expensive compost heap from the wasted food bought at the farmer’s market with best of intentions.

As a part of that, I’m also taking a more serious run at the whole gardening thing in our community garden plot.

This actually started last fall when I turned and planted the entire 20′ x 30′ (approx) plot with fava beans. Now, we happen to love fava beans, but not that many. There was an ulterior motive.

Namely, fava bean plants do a brilliant job of pulling nitrogen out of the air and fixing it into the cells of the plant itself. As well, since favas are such a vigorous over-winter growth in this climate, they nicely shade and choke out most of the weeds that would be sprouting about now.

To put the nitrogen into the soil, the bean plants must be worked into the soil. Last year, I did this largely by hand (with a much smaller number of favas) by digging holes, chopping up the plants with a shovel and turning them into the soil. It worked, but not terribly well as it leaves potentially large air pockets in the soil that plants hate.

This year, I used Blue Blade (pictured at left). Or the scariest damned Make-style hack ever. It is one of the various inventions used by the gardeners in plots around mine. (No, I didn’t make this — if I had, the sides would be a bit sturdier and I would have used nylon nuts to keep the damned thing from falling apart.)

Shredded Fava Beans And Shredder

It is a pretty simple device.

  • Rip apart an old lawnmower
  • Cut a piece of plywood in a circle the same diameter as the lawnmower’s deck
  • Drill hole in middle and bolt lawnmower engine to plywood
  • Attach blade to bottom
  • Attach plywood to a sawed off barrel (In this case, plastic… lending to the fear factor)
  • Cut a 2.5″ in diameter hole to the side of the engine
  • Attach a plastic tube used to feed in the favas
  • Grab a handy stick and jam the engine’s throttle wide open because you don’t have a throttle cable or dead man’s switch anymore

Then? Fire the damned thing up and feed favas, weeds, and any snails/slugs into the tube.

The end result is green gold. A thick mat of minced favas that are easily spread and turned into the soil. Not only does it add a ton of nutrients to the soil, but the fibrous matter loosens the soil quite a bit and makes subsequent planting and weeding tasks a ton easier.

I’m still letting a good sized patch of favas grow to full maturity. Which is frightening. I picked up fava seeds from Peaceful Valley Farm & Garden Supply along with a rhizobacteria that grows in symbiosis with the plant to maximize nitrogen yield through excellent plant growth & health. In my case, this means a solid mass of 6 foot tall favas!

Peaceful Valley or “” is an awesome company. They have been very helpful and have an amazing assortment of heirloom seeds.

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12 Responses to “Blue Blade; Destroyer of Favas”

  1. annbb says:

    Wow! That works reallly well! Have you started your seeds yet?

  2. Autumn says:

    I love the scariest damned Make-style hack ever! Would you be willing to let us re-post this at with a link back to your blog? Thanks!

  3. Peter Bierman says:

    Yikes! A sheet of 14ga steel bent into a cylinder at techshop would make that thing a lot less likely to take out someone’s ankles. shiver

  4. Mel says:

    Do you think you could get a similar result from planting a working mulching mower over a big pile of fava plants? Or is the feeder an integral step in getting the fine result?

  5. bbum says:

    You really want to pull the plants out by the roots and they really do need to be fed through the blades from the top. If not, you’ll end up with big chunks of fava plant which will not mix into the soil well and can lead to air pockets, which is a great way to encourage root borne diseases. Alternatively, you can just toss all the favas on a compost heap and let ’em sit for a season. Till the composted ones into the soil and make a new heap out of next season’s favas.

    A better design would be to take a standard mower, cut a hole through the deck, weld on a steel tube of the appropriate diameter and then mount the entire thing on mount the entire thing on a wooden barrel or steel cylinder as Peter suggested above.

    This is a total hack; it works, but I would not recommend this particular design to anyone for any reason.

  6. John C. Randolph says:

    Does it help to let the plants dry out first?


  7. bbum says:

    Nah. This things shreds as many favas as you can fit in the tube at once; 5 or 6 plants. No problem.

    If they were dry, it’d just be more dust. And spreading the damp plants, then working ’em into the soil, seems to really make working the soil that much easier and improve the quality of the mix quite a bit.

  8. Richard says:

    wow, i have never heard of using plants to help feed plants, seems a bit canabalistic, but i bet it would work. thanks for the info.

    [ed: uh…. right… silly spammer just wrote, perhaps, the most inane comment ever. Link removed.]

  9. Jeffrey J Hoover says:

    Whoof! Plastic cylinder holding back spinning metal blades of death with a wide open throttle? Yikes!

    Um cage of steel mesh? 55 gal drum?

  10. Mental P Mama says:

    Now that is impressive. Are you coming out here to help your sis in her foray at our community garden? I have high hopes;)

  11. Amie says:

    That is the biggest damned cuisinart I have ever seen! What an ingenious idea! Hope you see a huge return via awesome soil and super healthy vegs.

  12. In The Loop » Blog Archive » Blue Blade; Destroyer of Favas says:

    […] by Bill from his Bay Area community garden […]

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