The Guerrilla Gardening Guidebook – Soil Conditions

© chriscondello 2013

“Sunset Clover” – Hamnett Place Community Garden – Jeanette Street – Wilkinsburg, PA – Clover growing in the lawn of a local community garden… Clover is often one of the first plants to take root in a recently disturbed lot… If it is not… Then you should be planting it… A nitrogen accumulator that benefits the topsoil through decomposition…

Soil conditions

This post is part of a larger body of work titled ”The Guerrilla Gardening Guidebook”. For the introduction and table of contents please click here

When guerrilla gardening in urban environments, all soil should be considered contaminated fill until you have a good reason to believe otherwise. Lead has been banned from household paint since 1978, all homes built before this time are possible sources of contamination. For this reason I always recommend testing your soil before breaking ground. Empty lots typically had structures on them at one time, the way the building came down can affect the level of contaminants left in the soil. For example… A wood frame house that burnt to the ground will have a greater effect than a brick building that was professionally demolished.

When a building is built, or a road bed laid, the extent of the excavation extends well beyond the actual perimeter of the building or road. The excavation will be considerably larger to facilitate construction. The subsequent soil that is used to fill this hole back up is never black compost-gold, it is always the cheapest material available. Therefore all of the “no-till” concepts are pretty much thrown out the window. Soil structure less than 50 years old, in my mind, is exempt from the idea that tilling will disturb the existing layers of soil.

Much of the soil I find in my neighborhood is a mixture of yellow and red clay, shale, slag, coal and sand… Only occasionally do I find black topsoil deeper than a few inches, and the places I have found topsoil deeper can often be explained by a past homeowners love of gardening. Tilling is often necessary, and amendment required.

Oftentimes, the brown spaces near streets and sidewalks are only filled with stone and sand. Plants will often be seen growing in these desolate spaces, but they are only growing in a thin layer of garbage and debris that has broken down at the surface. Cut the weeds to the ground, cover them in newspaper, and fill it with as much rich, organic material as you can fit. Plantings go right in this layer, when putting this bed to rest do your best to mix your new layer with the existing one… The following year repeat…


“Forget-Me-Not” – Lamar Avenue – Wilkinsburg, PA – Growing in the decaying garage at the end of the alley behind my house… Freemasons began using the flower in the 1920’s as a symbol not to forget the poor and desperate… Perfect flower for Wilkinsburg…

If food is in your garden plans, get a soil test done regardless of cost. If you are reading this and thinking it is not really required, Google “lead poisoning” before reading any further. Plant roots often reach much deeper in the soil than you would think, a few inches of compost placed on top of 12 inches of heavy metal contaminated fill does nothing to protect you from the possibility of lead poisoning. If the space is relatively small, you could always excavate by hand and fill the hole with organic material. The issue of what to do with the soil is typically the bastard of the situation, there’s really no good answer… Phytoremediation would be my answer… Read my post about it here

The urban areas targeted by the average guerrilla gardener are commonly vacant lots that at one time contained a structure. Demolition contracts typically go to the lowest bidder, and corners often have to be cut. In my neighborhood, the second and third floors are typically ripped off and placed in a dumpster. The rest of the structure is then pushed into the basement, and covered over with a few inches of the cheapest fill available. Brick buildings are the worst, they can make the tines on even the best rototiller look like butter knives.  The only advice I can give you is get a shovel, mattock, and pry bar, and start digging… Remember to save the bricks for borders later!

The good news of the soil situation is, you can always build up. Raised beds with a barrier between the existing soil and the bottom of the bed are often the only choice. This will effectively stop the plant roots from accessing contaminated soils below, as well as keeping the edible leaves high enough off the ground to stop contaminated splash.

Soil should look, smell and feel alive, the living organisms are what work to eliminate contamination. The incorporation of organic material is often the starting point of remediation. If your soil is lifeless and dead, add organic material… It is the key ingredient to a healthy garden.

Organic material is available from all kinds of sources, I often just rake

plant petunias and question everything – chriscondello

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