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Wednesday, June 8, 2011

Water, Water, everywhere but not a....

We've had plenty of rain over the last month, climaxing in a fine thunderstorm on Sunday. Yet, Chicago summer being what it is, we're now basking in sticky 80+ temperatures. The parking lot and gardens went from swampy muck, to grimy standing water, to cracked and dry earth in no time. What's an urban gardener to do?
Quite a lot to, actually. Like most things, an ounce of prevention is worth a pound of cure. Failing that, we can still make the best of our situation. Some tips:

Topsoil: Nothing beats good well-mulched topsoil with plenty of humus. Good humus can retain 80% of its weight in water. Don't think mulch is just leaves or wood-chips, many plants can be used similarly. Squash, with nice broad leaves, can create cool damp micro-climates around their base, slowing evaporation from the soil. (Added benefit, mulch keeps the weeds out!)

Water well! The U of I extension office has some great tips. Among them: 1 inch of water a week is sufficient. (It encourages deep rooting). Water early in the morning to avoid water loss from evaporation and damp leaves at night (Watch out fungal diseases!).

But what about all that gravel, and those mosquito breeding grounds, the pools of standing water? Use that rainstorm as a chance to do some practical observation. Where is water pooling? Can we put some hardy pioneer species there? If not, can we catch that water in a rain barrel, or divert it a bit?

Or...

A classic permaculture solution is a bio-swale. An undulating mound slows water run-off, allowing it to collect and soak into organic matter rather than spill onto pavement. We've been incorporating this into the design of our herb spirals. The interlinked paisley-spirals sit at the top of a gradient across the parking lot. This way, water won't rush down and flood our low-lying beds. This has the added benefit of creating lots of surface area for planting, and room for lots of intersecting edges; potential zones of maximum species diversity and potentially symbiotic plant interaction. This also keeps our bio-swale from looking like a wall and keeping friendly neighbors out. Of course, we have to watch out so that rain-water doesn't cut deep rivulets between the mounds; another reason for the interlocking pattern we've chosen.

Storm-water runoff is one of the biggest pollution problems cities face. The world-over, freshwater is a precious resource. With a little ingenuity, we can turn that waste into a much needed resource. (Next up- how to re-reverse the Chicago river!)

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