How To Create A Coastal-Style Garden In Tennessee
The trick is‚ it doesn't have to be by the sea․ It's all about the movement in the plants‚ the color palette‚ and looser plants․ The only thing that you need to do is think about the drainage‚ because Tennessee clay is not like coastal sand․ Gardening in Tennessee (USDA zones 6b through 7b) doesn't preclude having that kind of coastal ambience; it just requires different soil preparation and plant selection than what one would normally encounter on the actual dunes of Charleston‚ South Carolina‚ or Wilmington‚ North Carolina․
This is really a style question more than a climate-matching one․ Coastal gardens are all about texture: feathery leaf shapes that catch the light‚ billowing foliage that moves in the breeze․ The colors are mostly subdued and naturalistic linked silver greens‚ blues‚ lavenders and taupes‚ grays․ You can get that palette in Knoxville and Nashville just like you can in Savannah‚ but here you need to use plants that are adapted to this humidity and heavy clay soil‚ not those that are adapted to beach conditions and not made for an inland winter․
Start with the soil‚ not plants․
Coastally‚ the soil is sandy and offers good drainage․ Tennessee soil is generally moist and can be compacted․ This is especially important in Middle Tennessee and East Tennessee‚ where clay soils predominate․ Two to three inches of composted pine bark or leaf mold should be worked into the entire bed․ If this planting is going to be in a low area that stays wet after a rain‚ build up the bed four to six inches above grade․ This is arguably more important than the plants themselves; after all‚ most airy‚ fine-textured plants that read as "coastal" - ferns‚ fine grasses‚ low groundcovers - rot quickly under standing water․
Groundcovers That Set The Coastal Tone
A typical coastal-style flower bed will typically have some low-growing groundcover which spreads out‚ providing a backdrop of color to the flower bed․ One of the best groundcovers for this purpose is ajuga reptans (Carpet Bugleweed)‚ a compact low-growing perennial with sheets of bronze purple matting foliage and blue-violet flower spikes in spring․ It spreads quickly and can be used for the same purposes as beach grasses to cover sand dunes․ It grows in part to full sun and is drought tolerant in the summer․ In Tennessee‚ it generally takes six to eight weeks after planting plugs to establish‚ and eight to twelve inch spacing allows for full coverage in one season․
For height contrast and texture‚ of course Bracken Fern works wonderfully․ Its fronds have that lacy wind-swept look that you just associate with the beach‚ and it remains much more vigorous in our climate's shade than true beach ferns would in the understory of shrubs and trees․ It will prefer a slightly acidic‚ well-drained soil such as you have just created with the pine bark amendments‚ and‚ as it spreads naturally by rhizome‚ it should be allowed to naturalize rather than controlled into a tight clump․
A Fragrant Anchor Shrub
Every coastal-style bed has to have an intermediate height‚ somewhere between your ground cover and the tall trees‚ but not so tall that you can't see everything you have planted around it․ Carolina Allspice is a great choice for Tennessee gardeners‚ as a native Southeastern shrub․ It's acclimated to our rain and winter‚ too‚ and will bloom in late spring with rust-red‚ wine-colored flowers that smell of strawberries or bananas‚ although I'm sure that would be lost on a non-fragrant landscape planting․ It grows to six to nine feet (1․8 to 2․7 m) tall‚ in the full sun or partial shade․ It will tolerate partial drought once established․ The plant should be brushed past for maximum perfume‚ which is better dispersed when much closer to the plant․
Height And Shade From Trees
If you want the loose‚ somewhat unkempt vertical of the coastal maritime forests‚ no more - Box Elder Tree lets you have it! An honest open branching pattern that screens light‚ but never so much as to stop it․ Plus it grows quickly (two to three feet a year after establishment)‚ so you'll have shade before you know it․ And it tolerates wet soil better than most shade trees‚ so it is a good choice for a site where part of it does not drain as well after soil amendment․ Ultimately the tree can grow up to 50 - 75 feet (15 to 23 m) tall with a broad‚ spreading canopy; however‚ it requires at least twenty-five feet (8 m) of clearance from buildings․
Building The Layers
The trick is to create layers‚ not strata․ So ground cover like Ajuga in front‚ a little bit of Bracken Fern a little further back‚ or here and there through the Ajuga‚ a mid-story shrub mass like Carolina Allspice behind that‚ and above it all‚ a canopy tree like Box Elder․ Not all of these plants are beach dwellers‚ but they should not be planted in rows․ Because they are often drifts‚ plant a loose group of five to seven of the same groundcover or fern rather than scattering one plant among other plants․
Maintenance Realities
Despite their name 'coastal'‚ Ajuga should be divided every two or three years‚ when they become overcrowded‚ by lifting the clumps in spring and
