Fig. 3.30 7-5-2014 rwm

Plants’ water needs and tolerances determine their ideal Rain-Garden Zone. See plant lists in appendix 4 of Rainwater Harvesting for Drylands and Beyond, Volume 1, 2nd Edition, for more.

The average American household’s outdoor landscaping is the destination for 30–70% of the municipal drinking water piped in for domestic use. However, home gardening can instead be an exercise in conserving water—by simply choosing plants (preferably native, multi-use ones) and planting them according to their rain-garden zones so that, once established, they will receive just the right quantity of high-quality water they need to thrive—for free!

How can you begin—or further—your transition to landscaping with plants steeped in the culture and history of your area, landscaping that enhances rather than depletes your water budget?

In the latest reprinting of “Rainwater Harvesting for Drylands and Beyond, Volume 1, 2nd Edition,” and on my website I have revised appendix 4 by adding a Rain-Garden Zone column to the plant lists. The column indicates the ideal planting zone/location(s) for each plant within or beside a rain garden based on the plant’s water needs and tolerance—best placements listed first. There are three rain-garden zones:

  • Bottom – typically bottom of a basin or swale.
    Prone to temporary pooling of water and cold air (cool night air pools in low spots).
  • Terrace – typically atop a terrace or pedestal within, or on bank of, a basin or swale.
    Shallower and less-frequent temporary pooling than in bottom zone.
  • Top – area beside, not in, a basin or on its banks, where plant’s root crown stays high and dry, but plant’s roots can access water harvested in basin; top of berm.
    Driest and warmest of the three zones (avoids cool air pooling).

Note that the Rain-Garden Zone can also be used as a Greywater-Garden Zone when greywater is discharged into a water-harvesting earthwork or rain garden.

I have purposely tried to keep this Rain-Garden Zone classification simple, so when working with a team planting a rain garden, each plant can be marked on its planting pot (before planting) with its ideal Zone. All plants (in their pots) can then be placed in their ideal rain-garden zones within or beside the water-harvesting earthwork. Once you have everything where you want it, the planting can begin.

Read on here to nourish your understanding and implementation of rain-garden-zone planting techniques, including—for those of you not in Tucson—the simplest, most-enjoyable way to begin your own version of this plant list!

‘Drops In a Bucket’ Blog © 2014


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