Planting for Sustainable Landscaping: A Practical Guide for Tennessee Yards
Sustainable landscaping means designing and planting a yard that works with your local climate and ecosystem instead of against it‚ so you use less water‚ fewer chemicals‚ and less time fighting conditions your plants were never suited for in the first place․ For Tennesseans‚ that means using native plants suited to our clay soils‚ humid summer and Zone 6b-7b temperature swings‚ rather than trying to keep thirsty‚ non-native ornamentals alive through August droughts․
It’s not like having to tear out your whole yard and start over․ Most people just replace the plants that don’t work well with other plants as the beds are renovated or the picky shrubs die․ Here’s how to actually do it‚ with specifics instead of vague sustainability talk․
Start With What Tennessee Soil and Climate Actually Support
Middle and East Tennessee are mostly USDA Zones 6b-7a‚ with West Tennessee in USDA Zone 7b․ Our clayey soil holds moisture and drains so poorly that it drowns plants requiring fast drainage and rewards the moisture-tolerant plants that are accustomed to a period of wet followed by drought․ This is exactly the profile native Tennessee species evolved for․
Best native plants for here that take little care include:
* Other understory trees that tolerate clay and partial shade include Eastern Redbud and Serviceberry․ * Also Oakleaf Hydrangea tolerates both the morning sun and the Tennessee humid climate better than the others * Black-Eyed Susan and Purple Coneflower for full-sun beds: These require little water once established․ * Switchgrass and Little Bluestem on slopes (to stop erosion)‚ which have deep roots that thrive during our summer droughts * Tennessee Coneflower‚ found in limestone cedar glades of the Nashville Basin‚ is a good pollinator plant for rocky‚ thin soil
However‚ a redbud would have to be grown in Ohio nursery stock and shipped south‚ where it would take several years to acclimate to the hot‚ humid climate‚ but locally grown stock will not need that period of time to adjust․ The TN Nursery carries many of these native perennials and shrubs․
Water Conservation That Actually Works Here
The yearly rainfall in Tennessee is relatively high‚ with 50 inches‚ but it is in bursts rather than evenly․ With four inches of rain one week in April and none for three weeks in July‚ sustainable landscaping adjusts for such patterns rather than the unrealistic uniform․
Drip irrigation is more effective than a sprinkler system on a timer because the water is less subject to evaporation and wind drift․ Sprinklers can lose 30-40% of the water․ To minimize evaporation losses‚ drip lines should run early in the morning‚ before 8 a․m․
A mulch of shredded hardwoods or pine bark applied 2-3 inches thick can reduce moisture loss by as much as 25 percent and regulate soil temperature to reduce root stress․ The mulch should not touch stems or trunks‚ which promotes rot and pests when heaped against the bark․
Hydrozone: The trick is to group plants by water needs․ In other words‚ don’t water a whole bed just to keep a thirsty plant alive while drowning six drought-tolerant neighbors․ For example‚ native coneflowers and switchgrass would go in one zone‚ hostas and ferns in another‚ and any plants that like constant moisture in still another․
Build Soil Health‚ Rather Than Fighting Symptoms
While Tennessee is often associated with red clay‚ its soil is in fact rich in minerals․ Compost alone is sufficient to provide structure‚ while the addition of 2-3 inches of compost mixed in first 6 inches of soil at planting improves drainage for clay soils and holds moisture for sandy soils․
Do not use synthetic fertilizers․ They may result in faster growth‚ but do nothing for the soil biology and‚ with high inputs of synthetic fertilizer‚ will discourage the mycorrhizal fungal associations that help plants to access nutrients and water․ Compost‚ aged manure‚ and leaf mold feed organisms directly and can establish a self-sustaining nutrient cycle within 2-3 growing seasons․
If you are starting a new bed‚ get your soil tested at your county UT Extension office prior to adding amendments․ Most tests cost nothing but time‚ or $15 or less‚ and will tell you what your soil needs․
Manage pests without the use of chemicals․
Integrated Pest Management (IPM) means pest identification‚ accepting low levels of plant damage (most plants do not die from minor injury)‚ and treating for pests only when populations are at a level where the plant is at risk․
In Tennessee‚ encouraging natural enemies is effective; ladybugs and predatory wasps can reduce aphid numbers and populations when dill‚ fennel and yarrow are grown close to the vegetables‚ and no insecticides are used․ Installing bluebird and wren houses away from the garden’s center can attract birds that eat caterpillars and beetles during normal foraging behavior․
If needed‚ neem oil can control most insect pests with soft bodies (such as aphids and spider mites) and does not damage pollinators when applied in the morning or late evening hours․
Hardscaping and long-term structure
Hardscapes are also part of sustainable landscaping․ For example‚ permeable pavers or gravel driveways can allow rainwater to soak into the ground rather than traveling to storm drains‚ as is especially needed in Tennessee neighborhoods with clay soil‚ ponding‚ and erosion․ Stone or brick reclaimed for use in retaining walls reduces the amount of material that needs to be quarried and is often cheaper․
Similar timelines can be found by:
Native perennials usually take a full season to establish root systems‚ so don’t judge the water needs of a new coneflower bed based on the first summer․ True drought tolerance is not realized for the first year․ Oakleaf hydrangeas become low-maintenance in 2 or 3 years when they have reached their full size․ The only ““cost”” of waiting for a sustainable landscape is time․ That time pays off in reduced watering‚ fertilizing‚ and pest management in as little as three years․
Perhaps start small‚ and just try converting one bed this fall․ Then see how it performs in the summer before expanding․ The native plants offered at TN Nursery are also easier to install‚ because they were grown from seed that is ecologically suited for the existing soil and weather rather than experimenting with mass-marketed big-box nursery plants․
