By Ann Barnes, EMGV

The Challenge: My home’s backyard slopes downward. A previous owner decided to create a more usable backyard by building a retaining wall to create a flatter space near the house. The upper part of the yard features a large built-in bench and a garden bed containing a row of rhododendrons. Further away from the house, the lower portion of the backyard is a wooded natural area, providing quite a bit of shade to the entire backyard. 

Over the years, I had noticed that the upper part of the backyard was often soggy during wet weather. During and after storms, water would puddle near the bench and in the rhododendron bed. The rhododendrons in the center of the bed where the most water pooled, declined, and some died. To try to combat the problem, I hired a contractor to install a French drain. While this was successful in keeping water from puddling around the bench, it did not solve the problem around the shrubs. Every heavy rain caused standing water for hours afterward and left the area muddy.

After losing the third of six rhododendrons, I knew I needed to make more changes to the drainage before trying to plant anything new. A dry stream seemed to be the ideal solution – it would add an interesting focal point to the landscape while directing water away from the shrubs and allowing it to percolate into the ground.

Planning: The new stream needed to channel and contain water away from the landscape bed. Before I could create a design, I needed to make careful observations of where standing water was a problem. Yes, that meant standing in the middle of the yard in the rain marking puddles with flags so that I could do the designing and digging in nicer weather.

Natural streams are irregular and winding, so I outlined a meandering stream path using some garden hoses. The stream is at its widest and deepest near the mid point of the landscape bed, as this is where standing water was most prevalent. The stream width ranges from 12″ to around 3′ After settling on a path for the dry stream, I used spray paint to mark the outline and removed my hoses.  

Since I had had utilities marked for a previous garden project, I knew there were no buried wires in the area. If you aren’t sure, call 811 before doing any digging in your yard.

The Hard Work: From each bank, the stream slopes to a depth of about 3”. I created deeper pools in some areas to encourage rainwater to drain away from the landscape bed instead of puddling at the bases of shrubs. I was careful to leave as many roots of the remaining rhododendrons intact as possible to avoid stressing the plants. Digging the stream in my spare time took a couple of weeks, but a determined team could have finished in a weekend. Once the soil was removed from the stream bed, I turned on a sprinkler to see if the stream was directing water away from the shrubs. Success!

I added a thin layer of gravel along the bottom of the stream as a base. Large rocks had once been the landscape bed’s border. I reused them, arranging them as naturally as possible in and along the stream bed along with a few more I unearthed while digging. Finally, a ton of smooth river rocks were delivered and moved into the dry stream. Using rocks similar to those found in the area will provide a more natural look, so I kept this in mind when purchasing stone for the stream.

Once the stream was complete, I added plants. Matching the existing rhododendrons would have been difficult, so I chose Pieris japonicum, Illicium parviflorum, and a Japanese maple (Acer palmatum dissectum) to replace the shrubs that had died. Shade tolerant perennials, including many hellebores and ferns, were planted and the garden was finished with a fresh layer of mulch.

The “Finished” Product: (no garden is ever finished, is it?)

The dry stream has been very effective at moving rainwater away from the shrubs and perennials and is one of our favorite views from the house.

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Lessons learned: Some online tutorials for creating dry streams recommended lining the stream bed landscape fabric before adding gravel and rocks. I opted to skip this step, but wish that I hadn’t. Soil and debris accumulates in the stream, and has covered some of the river rock. A landscape fabric base would make cleanup and maintenance easier. Currently, it is difficult to know where the bottom of the stream is supposed to be and to be sure I’ve uncovered all buried river rocks. This stream is several years old now, and I am planning to lift the rocks and add landscape fabric under them.

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If you have a larger, sunnier area than my backyard, you may wish to consider building a rain garden instead: 

Rain gardens are shallow bowl shaped landscaped areas that allow rainwater and runoff to filter into the ground. A rain garden can hold water for up to two days and can help prevent erosion. Native plants and shrubs that are planted in the rain garden attract beneficial insects and wildlife. There are some do’s and don’ts for choosing a site for a rain garden, including: 

• Do not place rain gardens uphill of homes, septic systems or wellheads  
• Locate at least 10’ away and downslope of the house foundation, crawlspace or basement (if home is on a slab locate downslope of foundation).  
• Locate 25’ away and downslope of a septic system drain field.  
• Locate 10’ away and downslope of a well head. 
• Avoid underground utility lines BEFORE you dig (Call 1-800-632-4949 or 811 in NC).
• The best location for the garden will be in partial to full sun (at least 4 hrs of sunlight).

Resources:

Rain Gardens:

https://chatham.ces.ncsu.edu/rain-gardens/

https://forsyth.ces.ncsu.edu/wp-content/uploads/2016/03/RGmanual2015.pdf?fwd=no

Dry Streams:

https://s3.wp.wsu.edu/uploads/sites/2079/2014/02/drystreambeds.pdf

French Drains:

http://extension.msstate.edu/blog/how-install-french-drain-0