Sustainable Shady Dry Gardens
Drought tolerant gardens are becoming increasingly popular for some excellent reasons. First of all, they reduce our dependence on water during the dry summers, when regional rainfall is minimal. Once established, with husky, wide-reaching root systems, these plants can fend for themselves, needing little or no supplemental water except in extreme circumstances.
Second, drought tolerant plants tend to prefer compost over fertilizers. This makes them easy to please with an annual mulching program and more independent and less needy when life gets complicated. Thus, dry gardens reduce the use (and overuse) of high-nitrogen feeds that tend to end up in our streams, ponds, rivers, and major water ways like Puget Sound.
Seldom Bugged By Bugs
Thirdly, many drought tolerant plants are not very palatable to pests. Plants that resist moisture loss often have hairy, leathery, or dense foliage that doesn’t make for easy snacking. Pests from deer to aphids and slugs tend to prefer a diet of tender greens that are more easily penetrated and less fibrous.
Lastly, a well chosen palette of drought tolerant plants can create a handsome and enduring garden that holds its looks and character with very little care. There is still plenty to do for those who love tinkering in the garden, but for those who are getting older (and/or busier), sustainably designed dry gardens can offer freedom from the tyranny of prima donna fusspot plants.
Some Basic Principles To Consider
Most of what has been written about dry gardens concern dry, sunny sites. Many sites offer ideas about of plants suitable for sunny sites, but less is commonly available for shady gardens. There is no reason why dry gardens won’t work in shady sites as long as a few simple principles are taken into consideration.
Our native woodlands offer an excellent model for dry shade gardens, since our paucity of summer rainfall means that natives need to get a grip or die. Some native flowers resolve the drought issue by going dormant in summer. Many shrubs and perennials have developed thick foliage and wide roots that help keep plants hydrated even in dry times.
In dry shade settings, I choose lots of native woodlanders, especially evergreens like huckleberries, sword ferns, and salal that provide structure through the seasons. Many Mediterranean, middle Eastern, and Asian bulbs also flourish in a dry shade garden, from crocus, hyacinths, and Greek windflowers (Anemone blanda) to many kinds of lilies and rare aroids (Jack-in-the-pulpits).
Front Loading The Care Package
Quite a few plants are fairly drought tolerant if given a good start. Amend soil well with plenty of aged compost, and soak planting areas well, not just each planting hole. Immerse each plant in a bucket until no more air bubbles appear, making sure the soil is completely saturated before planting. After planting, water in well and top mulch with moist compost or aged dairy manure (it’s seedless). For the first two years, be especially attentive to watering needs during hot spells and prolonged dry periods.
Many rhododendrons are surprisingly able to handle summer drought once their rot systems are well developed. With rhodies, the rule of thumb is that the larger the leaf, the less sun they can handle gracefully. Among the large leaved types, Rhododendron campbelli and the Loderi hybrids such as ‘King George’ are very drought tolerant once established, as may be seen in old, long-neglected gardens where they have lived undisturbed for decades. Our native Western rhody, Rh. macrophyllum, is not surprisingly another fine performer in dry gardens.
Among the more compact types, many of the yaks (Rh. yakushimanum hybrids) are good dry garden candidates, as are many of the 2-3 footers. Whatever the leaf size, all need an excellent start with at least two full seasons of supplemental water and an annual deep mulch of compost to thrive in dry garden settings.
Add Some Shady Companions
Under their feet, consider adding evergreen ferns, from our native sword and deer ferns to autumn ferns and many other members of the Dryopteris clan. Deciduous ferns that peak in summer and can take dry shade include our native lady fern as well as royal and ostrich ferns. White-veined Japanese painted ferns bring a gleam of light into dusky corners. Here again, a year or two or care earns many years of benign neglect with good results.
Foliage perennials can contribute far longer than those which offer showy but fleeting flowers. Once established, hostas are good dry garden performers, again needing plenty of compost mulch to keep them thrifty. Tough as nails, Brunnera ‘Jack Frost’ offers striking white-veined leaves and fluffy blue flowers that look lovely in shady woodland settings. Rodgersia, Mukdenia, and Acanthus offer bold foliage that holds its own amongst shrubs and small trees.
Perennials For Dry Shade
Flowering perennials for dry shade include hellebores of many kinds, which tend to have attractive foliage in summer and carry their dangling bell flowers in winter and spring. Japanese anemones bloom in shade or sun with aplomb. I often plant the various wood spurges such as Euphorbia martinii, E. amygdaloides, and the evergreen E. robbiae. This last is a running groundcover that is best used where room is plentiful and the understory sturdy, since it is the quintessential thug, but it is an invaluable carpeter for a tough spot.
For textural contrasts, mix in some evergreen shade grasses such as Carex morrowii, a charmer with many color forms striped in yellow or white to bring a gleam of silver or sunny gold to a shady corner. A deciduous Chinese forest grass, Hakonechloa macra, does well in dappled shade and comes in six or seven variant forms, from solid green through various stripings to solid gold.
Great Ground Covers
Some of my favorite deciduous ground covers for shady areas include Northwestern natives like bunchberry (Cornus canadensis), wood strawberry (Fragaria vesca), wood sorrel (Oxalis oregana, which also has evergreen forms), and bleeding heart (Dicentra oregana). Evergreen choices include kinnikinnick and several creeping Oregon grapes (Mahonia repens and M. nervosa), both of which boast fragrant yellow flowers in late winter or early spring. I often use members of the bishop’s hat clan (Epimedium), which come in a wide range of sizes, textures, and flower colors.
This brief introduction will I hope entice you to explore the wide and exciting range of dry garden shade plants more fully. Good places to get more ideas are in shady old parks and cemeteries and neglected older homes with long established plantings. Good hunting!