Dry Shade Gardens
Dry shade is probably the most difficult environment for gardening. The environment is typically created by large trees, which coincidentally have large roots. The roots not only consume growing space, but of course they are sucking up as much moisture and nutrients as possible to support the trees.
There are a few things a gardener can do to improve a dry shade situation enough to help support other plants. Harnessing water is critical. To do so naturally, think along the lines of rain gardens. Whatever water becomes available needs to be encouraged to pool and seep into the soil slowly. Pay close attention to where water runs out and away from the area. Sometimes the very slightest slope goes unnoticed, carrying away valuable moisture. Terracing such an area can dramatically reduce runoff, sometimes a very small stone wall is all that is needed. Altering the grade of the area by piling on nutrient rich, moisture retentive compost and amendments can be accomplished at the same time. Do not attempt to “dig in” the amendments to avoid damaging tree roots.
Although lack of sunlight can also create difficulties gardening in dry shade, altering the shade environment by pruning and thinning overhead branches not only requires constant maintenance, but can sometimes adversely alter the appearance of your trees. Trees should of course be pruned and thinned regularly to improve air circulation, sunlight availability and healthy branching anyway, but dramatic alteration to increase the sun that reaches under plantings is difficult to do properly and to maintain. Planting selections appropriate to the site is much preferred to minimize maintenance and plant loss.
There always seems to be some trial and error when it comes to finding plants that thrive in dry shade. Be careful to search for plants that tolerate consistently dry conditions. Drought tolerant plants sometimes only tolerate the dry conditions for temporary conditions of drought and may not survive the consistently dry environment. Also avoid plants that do not compete well with extensive tree roots. And of course, choose plants that tolerate dense shade.
HOW TO CHOOSE PLANTS FOR DRY SHADE
Choose plants with bright foliage
Choose plants with lots of texture for added interest
Woodland natives can offer sturdy plants for dry shade, but watch out for invasive multipliers
Use plants that need a little more sun at the outer edges of the shaded site
Use plants that need a little more water where water pools best or where lawn sprinklers reach
Dry shade tolerant shrubs can quickly add volume, height and interest
Try vines that clamber up tree trunks or pillars
Remember that a plant that thrives is always prettier and more lush looking than a pretty plant that struggles and looks pitiful
Also keep in mind that species and cultivars within a genus of shade plants do not all respond the same to an environment. For example most hosta prefer moist soil and will not typically tolerate dry shade. But I have had great success in very dry shade with Gold standard and Sir Frances William. Likewise the genus Cranesbill (hardy perennial geranium) has many species, not equally tolerant of dry shade. The Bigroot Geraniums, Geranium macrorrhizum, seem to be the most tolerant.