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Saturday, May 31, 2014

Weeds to Riches

A Glimpse Back to 2012: "Before"
This is the earliest photo I have of this site, located just above the main garden. 

St. John's Wort can be a great medicinal plant, but when it is set free in the wild, it takes over with no regard for what it is overriding. (Here it is seen with an orange hue as the flowers begin to set seed.) Unlike knapweed, St. John's Wort does not stick to areas where the soil has been disturbed. I have watched it swallow up native sagebrush plant communities. In the past there was a lot of houndstongue here too, most of which I pulled manually in 2010 and 2011 before learning about sheet mulching. However, my attempts at pulling the St. John's Wort made it clear that I needed to take a different approach. Enter many truckloads of cardboard and a whole bunch of barley hay...

After applying a generous dressing of fresh manure for heat, then laying cardboard down and layering the barley hay on stop: smothering works! I used barley hay because it was available for free, and because it came with a cover crop seed built in. (Funny how this made it undesirable to others, but doubly useful for me!)

Little by little, the St. John's Wort retreats.

2013: The barley seed has sprouted and I've planted a few tiny rhubarb plants from my neighbor's garden. I've also moved some extra strawberry plants in from the main garden area and added more apple trees.

The rhubarb is growing, and the first smothered area is taking on new life... but in the foreground you can see there is still a lot of St. John's Wort to contend with.

I saw no reason why this project couldn't happen during winter, so I gathered up as many leaves as possible in the valley and brought them home at every opportunity -- for mulch on top of the cardboard.

This time around, I went without manure. While this method lacks the heat component, it also avoids introducing new weed seed to the site. The manure worked great for helping rot the St. John's Wort plants under the cardboard (and for building rich soil), but I did find new weeds cropping up as the cardboard decayed. I'm always up for tweaking the process and comparing results. 

Slowly the weeds made way for cardboard and leaves. I also added an above ground hugelkultur bed, but that is a topic for another day. 

In some places I experimented with using old cotton fabric sheets instead of cardboard, and they were a lot easier to work with, with the added benefit of being much more durable. 

I am thankful for all the people and businesses who have shared cardboard and leaves with me!! Thank you!

Early May 2014:
The snow is gone, and so is the St. John's Wort! 

I added Ponderosa Pine branches from some forest thinning that my husband did. These branches turned out to be critical to the success of the cardboard/leaves method, as we had some strong spring winds that began blowing the hard-earned leaves away! As I ran about laying more branches on top, they did the trick in securing the leaves to the ground. *Whew* This ain't Kansas, but the winds sure can blow sometimes. 

I'll take layers of debris over weeds any day. There can be concern about fire hazards when layering debris. However, if you irrigate, pine needles and leaves turn into beautiful compost. Even without irrigation, over time this is a soil-building process.

This is how it looks today, May 31, 2014. The orange hue you see now is from pine needles, which will rot and make the soil richer -- helping other, more desirable, plants to grow. 

Zooming out a little, you can see the context of the larger area. The posts form cages around apple trees, six different varieties. What was once a choked-out noxious weed zone is now supporting rhubarb, strawberries, horseradish, garlic, lettuce, valerian root, and asparagus. I didn't actually intend to make a garden here, but after hauling in loads of manure to help rot the weeds out, and after seeing the space open up, it naturally became our "garden annex." 

Weeds to riches, no doubt about it!


  1. Julie,
    very interesting to read and see the pictures! Thank you for sharing this. Looking forward to the next post!
    Greetings from far away in the Netherlands! Tanja Thomas

    1. Thanks, Tanja! Thanks for checking it out. Greetings from North-Central Washington! Zijn goed.

  2. Excellent account. Very interesting about the St. John's wort. I'm more curious about your use of manure under the cardboard to provide heat. How much manure did you use and what kind? Just curious how that all works. I'm building sunken beds in Colorado and someone else mentioned using manure to create heat in the sheet mulch layers...I'm just not sure WHICH layer to add the manure in and how that works. On the bottom?

    1. Thank you for your comment, Crystal. I use horse manure because it's what I have available and it is well-known for being hot. How much is really dictated by your supply more than anything, but also to a lesser degree based on how soon you want to plant it and how fresh vs. aged the manure is. It will scorch your plants -- I learned that the hard way even though I had read about this happening. If you're going to plant it in less than two months, I would put the manure lower down in the layers. If you are doing it in the fall for spring planting, it can be closer to the surface and you can be more liberal with it.

      I like to put it as the layer directly under the cardboard so that it can help rot weed seed on the surface of the ground. The nice thing is, there is no set recipe. I used to follow a prescribed recipe for what to layer in what order, but over time I have found that many different variations can work great. If you are doing it mainly for weed control, then fresh manure is best because it's hotter, and you can't use too much. Just be aware that when the cardboard degrades, you will have weeds sprouting from the manure that you need to deal with. I just plan on covering certain areas every other year with cardboard, and it builds wonderful soil, or not using manure at all if I don't want to revisit a site anytime in the next few years. You can also do two layers of manure, one down at the bottom and one directly below the cardboard. Introduce a few earthworms if you don't have any, and they will multiply like crazy. Good luck and please keep me posted!


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