Friday, July 18, 2014

No-dig gardening: establishing paths and beds via sheet composting combined with a sterile medium such as Pro-mix (includes update on the sedum pathway)

A previous post (September 14, 2012) described how I established a little secondary path with no digging at all, directly over existing sod, by using cardboard, newspaper and sterile planting medium (pro-mix, wood bark) dotted with pavers, edged with limestone blocks and planted with Angelina sedum.

The path as first established in 2012-note sprigs
of Angelina sedum in sterile planting medium
The path today (two years later.)* The sedum is
fully established, and has lived through two winters.
This idea worked very well.  As predicted, a few weed seeds have blown in, and a few blades of grass poked up along the edges (in the cracks between where the newspaper/cardboard was laid and the limestone blocks which made up the path).  However, also as predicted, the sterile medium made pulling the weeds out very easy.

Based on the success of the path, this year, I established a new no-dig bed using the same system: composting the grass under cardboard, topped with a sterile planting medium and edged with limestone blocks.  This time, I planted forsythia bushes with an understory of perennials, as well as sedum.

As a first step, I closely mowed the grass under where the bed was to be. Next, I loosened the soil for the forsythia bushes using my favorite digging tool: a pick-ax** Next, I laid cardboard down, then laid limestone edging, same as in the sedum path, then laid pro-mix on that and heavily watered the entire assembly.  The next day,  I easily made holes in the still-wet cardboard over where the loosened native soil was, then planted the bushes in the ground, through these holes in the cardboard, just as I would do if planting in open ground.  The native soil and promix were somewhat mixed together, but the roots are mainly in the underlying soil, with the promix (which is, at most 2-3 inches deep) is mainly around the crown. (In the below photos, the bushes are surrounded by chicken wire to keep rabbits from gnawing the new plants).

Although the bush roots are in contact with the native soil through the holes in the cardboard, the perennials are simply planted into the pro-mix.  A capful of time-release osmocote with minerals, and a teaspoon of organic fertilizer was mixed into the promix by each perennial, as promix has essentially no nutrition in it.  As the underlying cardboard rots away, the perennials' roots will work their way through (the perennials will show they've reached that point by taking off in growth--this will probably occur next spring).  In the meanwhile, daily or every-other-day watering is needed, since pro-mix dries out easily.  Oh, I should mention that the pro-mix is covered with cocoa-hulls, as was the sedum pathway.

Using sterile planting medium in conjuction with cardboard and an edging makes it easy to create no-dig paths and beds directly over existing sod. The next post in this series addresses a different variation on this theme: top-dressing an existing bed with sterile planting medium. I'll put a link here when that post goes live.


*The pink flowers on the left belong to "lipstick" alpine strawberry plants,  a ground cover on the adjoining flower bed.
** Pick ax: much easier than a shovel for loosening soil.  Using the ax, not the pick, swing overhead to chop straight down, taking a wide stance.  Make others stand back--WAY the heck away from you. Make sure, too, that the ax head is seated before each swing, and that there is nothing overhead (tree branch) to tangle the swing of the ax. Search you-tube or ask someone who knows the correct use of a pick ax if at all unsure--a minimal goal for successful gardening is to go to bed with your skull intact, and the same number of toes as you woke up with.

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