Spring Newsletter: April, 2014 Issue: 20    
In This Issue
Was 2013 the wettest year?
Rain Garden Facts
Upcoming Workshops
Garden Tip #1 
Be sure to mow your lawn at the correct height. For turf-type fescues and bluegrass have your mowing height to 2 1/5 inches. The higher you cut the lawn the deeper the roots will grow helping it survive dry spells. Do not lime or fertilize your fescue or bluegrass lawns until late summer. 
Garden Tip #2
 Stake tall growing perennials such as foxglove and true lilies to prevent them from lodging.

Does Your Yard Measure Up?

We call it a Tennessee Smart Yard -- a yard that is in harmony with Tennessee's native flora, soil and topography. You don't have to be an expert gardener or landscaper to create a Tennessee Smart Yard. All it takes is a willingness to learn and a desire to build a yard that is based on the nine principles found in our handbook:


Right Plant, Right Place


Manage Soils and Mulch


Reduce, Reuse, Recycle 


Water Efficiently


Use Fertilizer Appropriately


Manage Yard Pests


Reduce Storm Water Runoff and it's Pollutants


Provide for Wildlife


Protect Water's Edge


To find out more information download our free

Garden Tip #3 
 You can selectively prune spring-flowering shrubs such as azalea, forsythia, weigela, lilac, beauty bush and mockorange to control their growth or improve their shape as well as increase their bloom next year.
Rain Garden Plants That We Love!

Now that we see how beneficial rain gardens can be let's talk plants! We have installed several rain gardens in the state of Tennessee and through some trial and error we have come away with a few tried and true native plants that we love to use in the garden.

Blue Flag Iris, Iris versicolor or Copper Iris, Iris fulva
These two Iris varieties are exceptional in rain gardens. Other varieties of Iris do not fair well preferring dryer conditions. Stick with these for rain gardens.

Blue Wild Indigo, Baptisia australis
You might think of Indigo as a prairie plant, but like the Iris not all are created the same. This variety of Blue Indigo does well in medium to wet soils and is very tough in changing water conditions. Perfect for the rain garden.

Fireworks Goldenrod, Solidago rugosa, 'Fireworks'
This hardy native perennial can withstand wet and dry conditions and provides a burst of bright yellow color in the late summer.

Mist Flower,
Conoclinium coelestinum
This is a great rain garden plant. This plant can spread creating a nice ground cover with bright purple blooms in the summer.

Blue Star,
Amsonia tabernaemontana
This is an extremely hardy native perennial usually found around wetlands in TN but does well in drier conditions as well. Has great little blue flowers in the spring and in the late summer to fall the foliage turns a nice amber color.

Ilex verticillata
One of our favorite shrubs for the rain garden. It's one of the hardiet native hollies. Requires male and female plants to set fruit, and females laden with red fruits make a spectacular sight in winter.

We also have a more comprehensive list of native rain garden plants on our website if you are interested in learning more. Click here

Happy spring everyone! We are so glad to see the winter months end! We are starting off this spring issue talking about rain! Rain showers bring May flowers! Our Co-Director Dr. Andrea Ludwig looks at the wet conditions we had over the past year and gives us some facts about just how much of that rain water we can capture in rain gardens. Want to learn more about rain gardens? We have a workshop coming up at the end of this month in Mt. Juliet, TN. Check out the information and see how you can sign up below. Also, we couldn't resist talking about plants, rain garden plants in particular. We posted our favorites and a link to a more extensive list of tried and true rain garden plants for Tennessee. Check it out!  Enjoy that spring weather, and get out in those gardens! I'm sure they have missed you all these months.

Thanks for reading!
The TNSY State Management Team

Andrea Ludwig
Was 2013 the Wettest Year on Record?
by Dr. Andrea Ludwig


It began with almost 13 inches of rainfall in January in eastern Tennessee, then throughout the rest of 2013 it seemed as though it rained every other day. But was 2013 the wettest year on record?  In recent memory, many of us think this to be the case. But, are our collective memories correct?  We can only know the answer to this question by examining the data and looking at historical rainfall records.  

In Knoxville, TN, average annual rainfall is 48". It is 54", 52", and 47" for Memphis, Nashville, and Chattanooga, respectfully. But as we commonly see in climate patterns across the southeast, actual observations from year to year can deviate substantially from the long-term averages. Daily rainfall accumulation is measured at weather stations across the state and made available online by the National Oceanic and Atmospheric Administration (NOAA, www.ncdc.noaa.gov). Total annual rainfall in 2013 in Knoxville, TN, was approximately 67". That was 19" or approximately 37% over the area's average annual rainfall. This comes as no surprise to the residents of East Tennessee who observed first-hand the frequency of rain and flooded streets. But was it really the wettest year on record as it felt? The answer is simply, no. The wettest year on record for Knoxville according to data from the NOAA was 1875, with an annual total of 73.7", or 54% greater than the current annual average. In spite of that, in looking back on 2013 we have good reason to think of it as the wettest year we can remember, because it was the wettest in 30 years. And this was the case across the state, where we saw 56" of rainfall in Nashville and 64" in Memphis, both well above their annual averages.   

Much of this can be attributed to that very first wet month of January.  Looking at total rainfall accumulation on a month-to-month basis, we can see why we think of 2013 as such a wet year. Because of the very wet January, the annual rainfall accumulation was higher than it had ever been in the previous 30 years, with only the exception of 1994 through most of the middle of the year (Figure 1).  

Figure 1

Another reason 2013 felt like such a wet year is because we had a relatively high number of days of recorded rainfall in Knoxville. In 2013, we experienced 90 days with rainfall accumulation of over 0.1". The average for this in the previous 30 years is 83 days. Again, 2013 was above the average, though not by a lot. There were 85 days of recorded rainfall in the Nashville area, while only 72 days in the Memphis area.

Rainfall patterns affect many aspects of day-to-day life, including food crop production, keeping the lawn green, and causing local flooding. The 2013 wet year meant that there was a large amount of water running off of our rooftops and pavements. A typical residential home sheds over 100 cubic feet of water from its rooftop with just 1" of rainfall. This runoff often drains directly into the nearest creek instead of soaking into the soil, as it did before we built on top of it. This means that it causes damage and flooding downstream very quickly, rather than infiltrating into the soil and slowly finding its way to the stream over a much longer period. Scientists and engineers at the UT Stormwater Management Assistance, Research, and Training (SMART) Center are helping develop ways to minimize the negative impacts of stormwater. This includes developing new practices, new tools for design, and new information and training materials. To find out about ways to make your lawn and garden areas absorb more rainfall, check out the Tennessee Smart Yards page for details on lawn care and using rain gardens (www.tnyards.utk.edu). You can also visit the UT Gardens Rain Garden to see how a rain garden soaks in runoff.  We estimate that in 2013 the UT Gardens Rain Garden soaked in over 5,700 cubic feet of runoff. That is enough to fill 2/3rds of an Olympic-sized pool!

UT Gardens Rain Garden

Dr. Andrea Ludwig is an Assistant Professor for the University of Tennessee and Co-Director of the Tennessee Smart Yards Program. Her specialty is watershed science and management with interests in stormwater management, stream and wetland restoration, and non-point source pollutant fate and transport.
Andrea Ludwig
Rain Garden Facts
by Dr. Andrea Ludwig

A rain garden is...a planted depression that is constructed in the pathway of stormwater runoff from rooftops or paved areas to capture and infiltrate it into the ground.

How much runoff will a rain garden soak up?

The average home size in the US is 2,700 sq ft. If we assume the average home is 2 levels, then the average home rooftop is approximately 1,400 sq ft. If a rain garden is designed to catch half of the rooftop runoff during a 1" storm, then an average rain garden will capture and infiltrate up to 430 gallons during that individual storm!  

The table below shows the relationship between impervious surface and generated runoff assuming that there is no storage on the surface. For every 100 square feet of rooftop (or other impervious surface), about 62 gallons of runoff may be generated in a 1" rainfall. 

Regional Rainfall and Rain Garden Retention in Tennessee

The tabular data below are generated from readily available rainfall data from the National Oceanic and Atmospheric Administration (data sets missing multiple days of record, but no more than 14 days annually) and limited to the 2013 calendar year.

Upcoming Workshops

Spring and Summer 2014  
Rain Barrel Workshops 

Come and learn about the benefits of rain barrels
and how to make your own.

May 10th, 2014  11am-12:30pm 
Bloomsday at UT Gardens located at 2518 Jacob Drive, Knoxville, TN
There is an additional charge to get into the Bloomsday festivities
Cost is $40 per barrel
No advanced registration for this workshop, first come first serve.
Only twenty barrels will be available to those who arrive first and want to make one to take home (for a charge of $40 per barrel)
Payment is due the day of the workshop if you are making one (cash or check only)

June 14th, 2014  10am-12pm 
Church of the Good Shepherd located at 5337 Jacksboro Pike,
Knoxville, TN  near Central High School
Cost is $40 per barrel
Space is limited, so register soon! Advanced registration is required
Payment is due the day of the workshop (cash or check only)

July 12th, 2014  10am-12pm

Town of Farragut Town Hall located at 11408 Municipal Center Drive, Farragut, TN
Cost is $40 per barrel
Space is limited, so register soon! Advanced registration is required
Payment is due the day of the workshop (cash or check only)

To register for the June 14th or July 12th workshops contact:

Parci Gibson, Knox County Stormwater Management
Phone: (865)215-5861

When you register, please provide the following information:
  • Which workshop you want to attend (June 14th or July 12th).
  • The number of barrels you want to make.
  • The number of people in your party.
  • Your email address and phone number.  If you don't have an email address, please just leave a phone number. We will only use this information when I send out workshop reminders.

The rain barrel workshop series is brought to you by the Water Quality Forum. The Water Quality Forum is a coalition of partners working together to keep our waters clean. For more information on the Water Quality Forum, please visit waterqualityforum.org or find us on Facebook at Water Quality Forum

Keep In Touch!
Ruth Anne Hanahan and Dr. Andrea Ludwig
TYN Statewide Co-Directors
Tennessee Water Resources Research Center
University of Tennessee
311 Conference Center
Knoxville, TN 37996
See Ya' in the Summer!
Thanks so much for reading!
Check back with us for details on our new projects
and more tips on achieving a healthy home landscape.
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