Beginner's Guide to Selecting the Best Shade Perennials for Your Garden
Shade perennials are plants which need less than four hours of direct sunlight per day․ Finding plants that fit the conditions in your garden is simply a matter of matching the dappled‚ partial or deep shade conditions in your garden to the conditions a particular plant prefers in its natural habitat‚ so that you won't have to do any more than plant it and forget it‚ year after year․ If you don't get it right‚ you'll have patchy‚ leggy growth beneath your trees for seasons․
The good news is that Tennessee gardeners have an easier time than many gardeners of the United States when it comes to shade gardening․ Most of Tennessee is USDA zone 6b through 7b‚ which means that summers are warm enough for plant growth‚ but winters are cold enough to provide chilling hours․ The trick is in picking which of the perennials can survive our muggy summer weather without rotting and our hard freezes with a minimum of damage․
What Makes a Perennial a Shade Plant
To cope with the filtered sunlight‚ shade perennials tend to have broad leaves or to flower early in the spring before the deciduous trees leaf out․ Hence, many woodland species‚ such as trillium‚ bloodroot‚ and trout lily‚ bloom during March and April and then spend most of the rest of the year replenishing their storage organs under the closed tree canopy․
Under your maples‚ oaks‚ and dogwoods‚ however‚ they have larger duties: Their roots hold the soil to the slopes before it is washed away‚ their fallen leaves form the leaf mold that feeds the soil bacteria‚ and their wide-horizoned habits maintain the moisture after the rains have subsided․ That's a godsend in Tennessee when July's clay-laden ground either bakes hard or is still damp from a spring storm․
Real Benefits‚ Not Just Pretty Leaves
They reduce your water bill․ Soil under a tree's canopy retains moisture better than an open lawn․ Shade perennials with dense root mats hold the moisture longer․ Once established (usually after the first full growing season)‚ most shade perennials require supplemental watering only during extended dry spells (two weeks or longer)․
Instead of robbing soil nutrients‚ the plants leave decaying stems and leaves that earthworms and helpful fungi decompose into nutrients for soil each fall when the plant dies back․ It is possible to considerably improve the tilth of compacted clay soil in a deep‚ well-built‚ well-planted shade bed in three to five years without even a bag of amendment․
They protect tree roots․ Mowing and foot traffic compact soil near trees‚ stressing roots more than most homeowners realize․ A groundcover of Partridgeberry or a drift of Heuchera around the drip line can help keep the soil loose․
They require less pruning and dividing than the sun perennials, and many of them‚ growing at a more leisurely pace‚ do not require the same frequent deadheading and pruning in the peak growing season every few weeks․
Best Perennials for Shady Areas Here are some of the best perennials for shady areas: Ferns - Ferns are hardy and work well in shady spots‚ and they come in many varieties․ Hellebores - Hellebores are a great choice for shady areas‚ as they thrive in darker conditions․ Pulmonaria - Pulmonaria are also known as lungworts․
In reliably moist shade‚ Astilbe is one of the more forgiving plants for the new gardener‚ with long feathery plumes of pink‚ red or white flowers from late spring to mid-summer (depending on the variety)․ If planted in a compost amended soil and kept watered (it is not drought tolerant) it should bloom from three to four weeks each year․ In Tennessee it needs to be kept out of the afternoon sun: too much hot sun in the afternoon‚ even if the soil is moist‚ can scorch its leaves․
Coral Bells (Heuchera) bloom later‚ but add ornamental value during the waiting time‚ with foliage ranging from purple through lime green to amber and lasting from spring until the first frost․ Heuchera prefers well-drained but moist soil‚ and does especially well in raised areas or other locations that do not remain waterlogged after rains․ These clumps are divided every three years or so when the center begins to become woody․
Red Trillium (Trillium erectum) - a native woodland wildflower in Tennessee․ Perennial․ This is a plant that you must be patient with․ It may take two or three years to become established and produce flowers‚ which‚ when they do appear in spring‚ will be deep maroon‚ three-petaled blooms․ Growing in rich‚ humus-y soil under deciduous trees will keep the plant in full sun for part of the year․ The following leaves will also give it shade‚ as they will have fallen and yet not opened․ This is not a plant for the instant woodland garden․
Although often overlooked by beginning gardeners‚ low mat‚ partridgeberry is a hardy essential plant․ Partridgeberry roots along the ground‚ forming a mat․ It typically grows under two inches tall and has a small footprint․ The small white flowers are followed by red berries that persist into the winter and provide cold weather interest after most other plants have finished flowering and gone dormant․ It tolerates deep shade better than almost anything else on this list‚ and is appropriate for that dark corner beneath an old oak․
Ferns are not pretty‚ but I have to mention them because‚ unlike the plants above‚ they provide texture in deep‚ dry shade․ Christmas fern and autumn fern thrive in Tennessee clay soil․ If you forget to water them‚ they won't sulk․
Getting Them in the Ground
For shade perennials in Tennessee‚ it is generally best to plant in the fall (September‚ October‚ November)‚ this way, roots will have time to get established during the cool season before the hot summer․ Spring planting is possible‚ but requires more watering during the first summer․
The hole should be twice as wide as the plant's root ball, and the native soil should be amended with compost and mulched with a shredded bark of 2 to 3 inches or leaf litter to simulate their natural forest floor environment․
Astilbe‚ Heuchera‚ Red Trillium‚ and Partridgeberry are sold as fresh growing field hardy and acclimatized to their Southeast growing environment‚ giving them a real head start over nursery-pot annuals, which must still become acclimatized to the soil and humidity of the Southeast․
I would recommend starting with just two or three plants that grow well in your specific patch of shade‚ and then seeing where it goes from there․
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