The Guerrilla Gardening Guidebook – Water


“Urban Rain Garden” – The Garden Table Urban Garden – Rebecca Avenue – Wilkinsburg, PA – Looking in the background you will notice a brick cutaway in the berm running along the abandoned house… I built that there because the gutters above leak profusely during rain events… The rain garden is my answer to the flooding that used to result because of this… Flooding that before this rain garden regularly covered 50% of the lot…


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

Whiskey is worth drinking, but water’s worth fighting for. Water is the great garden equalizer, any guerrilla gardener will tell you lugging water 4 gallons at a time in the middle of a heat wave sucks. Did you know you have to do this, like, every couple of days? Vegetables require regular water for the first month, then periodic water depending on the amount of rain that falls. Ornamental plants also require water during the first month of establishment, perennials that make it through the first year may never need supplemental irrigation. Annuals will need water throughout the entire course of their life, regular in establishment and periodic after.

There are options other than lugging water, observation during rainfall is often the key to success. Leaky gutters, when coupled with a rain collection barrel is just one example of collection without physical contact or alteration… A screen placed over the top will keep leaves and debris out. Where a roof does not exist, create one. One inch of rain, falling on a 1000 square foot roof will produce 600 gallons of water. One inch of rain on a small shed sized roof will fill a small rain barrel.

Even a rain barrel has its limits, with most commercial models topping out at 50 gallons. The important thing to remember is without a downspout, even a thousand rain barrels won’t do you any good. The answer to this problem is often as simple as meeting the neighbors, you would be surprised how receptive someone can be to a rain barrel when it does not involve any money or work on their part. If saving the local stream does not seal the deal, offer vegetables.

Storm water run-off is a huge problem in urban areas, pavement is quick to shed water and storm drains quickly drain that water to the local stream. In a pollution, litter and chemical free world this would be a perfect system, but we are not any of these things and therefore our watershed suffer the consequences. Urban lots consisting of compacted fill often do not soak up rainfall. Depending on the grade of the lot, much of that water is allowed to run right off it into the street. Every effort should be made to keep this water in the garden, or slow it down enough to allow it time to absorb into the earth.


“Grand Arrival” – Whitney Avenue – Wilkinsburg, PA – The sewers on our street our filled to ground level with litter and debris… This is the result of a Summer thunderstorm… As you can see by the photo not everyone thinks this is a problem…

Rain gardens and bioswales, when placed based on your observations of water flow, can effectively harness run-off for plant use. Water flowing down hill can be effectively stopped using a miniature bio-swale, excess water can then be routed to a central rain garden. Essentially this system is nothing more than small trenches dug perpendicular to the flow of water, the downhill side can be reinforced with a small dam made with the soil removed from the trench. This trench is then filled with loose organic materials, and covered in stones or wood mulch. This trench can then be routed to a central rain garden, with the garden beds radiating outwards from the collection garden in the center. My theory behind this is that the rain garden would distribute the collected water down the connected gardens, working essentially like a wick style irrigation system.

The plant-based answer I would give to the water problem is to use plants that don’t require supplemental water. Xeriscape plants like sedums, thyme and Echinacea often require no water beyond the time of planting. Any succulent will grow in the worst soil you can find, or the driest conditions you can throw at it. Some plants, like “Stella Dora” day lily are very common in parking lots, not only are they drought tolerant, they can be accidentally cut to the ground and still grow fast enough to continue blooming after a few short weeks. Native plants should be where your research begins, many of them have already adapted safety responses to the occasional drought or dry spell. Much more on plants later…

Properly amended soil holds more water than flat lifeless dirt, the amount of water your soil can hold has a direct relation to how much organic material it contains. Leaf mulch and grass clippings are often readily available in urban neighborhoods, these can be mixed into the soil, or layered on top to slowly decompose… You would be surprised how much organic material, when left on the surface of a garden, will be consumed and moved by the earthworms below… Learning about earthworms made me a lazy gardener… That’s right… I’m blaming it on the worms!..

Mulch is a material placed over the soil to reduce water loss through evaporation. Mulch is typically an organic material such as wood chips or hay, whatever is available locally is typically best. A mulch layer should be applied generously, keep in mind that water lost to evaporation only means you will have to replace that water later. When possible, a thick layer of mulch on top of your new topsoil layer will greatly increase the water holding capability of your garden.

plant petunias and question everything – chriscondello

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