Updated: Aug 13, 2020
There are two deterrents when designing a shade garden, the first being a limited plant palette due to a lack of light and the second obstacle of determining just how shady the new landscape exposure is. Then there’s the dominance of green foliage and the abundance of flowers in spring, followed by a dearth of colour for the rest of the year. Last but not least in the long list of impediments are those pesky trees creating that shade and their root systems which makes planting difficult at the best of times. Over my forty years of being a professional gardener I’ve learned which plants work under these conditions albeit largely through trial and error; so I thought I’d share a few tips to guide you towards a successful shade garden.
The Degree of Light
You need to determine the light exposure before you start purchasing plants, as there are many shrubs and perennials that thrive in open shade but fare quite poorly as the light diminishes. I break it down into three categories; partial shade, open shade and dense or full shade. Partial shade exposures receive 3-5 hours of direct morning or early evening sun in summer. Open shade gardens have dappled sunlight (through tree canopies) or bright indirect light throughout most of the day, while full shade exposures are those areas under trees or between tall buildings that receive no direct sunlight. Any afternoon sun exposure (from 12-4pm) should be avoided, as shade tolerant plants will often scorch or bleach-out in strong sunlight.
Understory & Feature Trees
It might seem odd to consider adding trees to a garden already shaded by the same, but if the existing ones are tall conifers with high canopies that allow a little dappled sunlight, then a few understory specimens might be appropriate. Your best choice here is our native Vine Maple (Acer circinatum) which is well adapted to low light and often has a multi-stem growth habit. Green Japanese maples (Acer palmatum) with intricate leaves such as ‘Koto no Ito’ or ‘Seiryu’ also work quite well but don’t expect any dramatic fall colour; red or burgundy-leaved forms should be avoided as these just fade to green in the shade. The hard to find Wedding Cake Tree (Cornus controversa ‘Variegata’) makes a stunning tiered specimen in open shade, just give it enough room to reach its full potential (20-25’ spread at maturity).
Acer palmatum 'Koto no Ito', Cornus controversa 'Variegata',
Flowering & Foliage Shrubs
Probably the biggest disappointment for most gardeners planning a shade garden is a lack of flower colour in regards to shrubs, but with partial shade exposures there is some hope. Let’s start with the hydrangeas which bring us midsummer to autumn colour; I find Hydrangea serrata the most shade tolerant species, with ‘Bluebird’ being an old-fashioned favourite and ‘Tuff Stuff’ a newer compact cultivar. The Oak-Leaf Hydrangeas (H. quercifolia) come in a close second and it might surprise you to learn that down in the southern states the Annabelle types (H. arborescens) are popular shade plants.
For earlier spring blooms and evergreen foliage try Camellia japonica, Lily-of-the-Valley shrub (Pieris japonica), some rhododendrons such as ‘Snow Lady’ or ‘PJM’, as well as the underappreciated Mountain Laurel (Kalmia latifolia) with its intricate buds and two-toned flowers. Some deciduous shrubs to consider are the very shade tolerant Japanese Rose (Kerria japonica ‘Pleniflora’), the beautifully scented Carolina Spice Bush (Calycanthus floridus), Enkianthus campanulatus which is native to open woodlands in Japan and many of the deciduous azaleas, including the hardy ‘Northern Hi-Lights’.
Of course I would be remiss if I didn’t mention a few standard shade shrubs such as Aucuba japonica with its evergreen variegated foliage and occasional red berries. Japanese Aralia (Fatsia japonica) works well in those fence corners with its bold tropical foliage and ultimate height of around 8-10’; it also comes in variegated forms. The mid-sized (3’) Skimmia japonica makes a great foundation shrub with male plants such as ‘Rubella’ and ‘Rubinetta’ carrying red flower buds throughout the winter and females such as the self-fertile ‘Reevesiana’ producing showy scarlet berries. For fragrance try the evergreen Christmas Box (Sarcococca) which comes in the shorter humilis (18”) or the arching ruscifolia (3-4’ tall) with their jasmine-scented late winter blooms. All of these standards thrive in deep shade.
Our native Oregon Grapes (Mahonia aquifolium, nervosa and repens) all work well in open shade, providing vibrant yellow blooms for the hummingbirds, edible blue berries and even bronzed winter foliage.
Aucuba japonica 'Variegata', Calycanthus floridus, Camellia japonica 'Jordan's Pride', Hydrangea serrata 'Bluebird', Kalmia latifolia 'Carousel' & 'Olympic Fire', Kerria japonica 'Pleniflora', Mahonia nervosa, Azalea 'Northern Hi-Lights', Rhododendron 'PJM', Sarcococca ruscifolia
Groundcovers Are Your Best Friend
When designing a garden with limited light and shallow soils, sometimes your best option to fill those difficult spaces is with a groundcover. While I no longer recommend using Lamium or English Ivy due to their invasive nature, I still plant Periwinkle (Vinca minor) where gardens don’t interface with nearby forests - as the white, burgundy and purple flowers are quite attractive. Japanese Spurge (Pachysandra terminalis) makes a nice 8” tall evergreen carpet and comes in both variegated and glossy (‘Green Sheen’) forms. Our native Redwood Sorrel (Oxalis oregona) makes a dense green shamrock understory with white flowers and a purple reverse on the foliage. Lily-of-the Valley (Convallaria majalis) provides the best of both worlds with fragrant white flowers and dense green foliage, although the red berries are quite toxic. Sweet Woodruff (Galium odoratum) has a reputation for being a bit aggressive but it usually grows well below most ferns and perennials. Another native plant worth looking at is Bunchberry or Cornus canadensis, a slow-growing perennial with tiny white dogwood blooms followed by clusters of red berries.
Cornus canadensis, Oxalis oregana, Pachysandra terminalis 'Variegata', Vinca minor 'Illumination'
Perennials and Summer Dormancy
Hostas and ferns are obvious choices when planting a shade garden, but don’t settle for the ordinary as ferns come in many colours (revisit my ‘A Ferntastic Voyage’ blog) and there are some truly spectacular hostas out there such as ‘Rainforest Sunrise’. The rest of the perennial palette can be a little focussed on spring flowers, with Bleeding Hearts (Dicentra), Trillium, Fawn Lily (Erythronium), Wood Anemone (A. nemorosa), Corydalis flexuosa and Solomon’s Seal (Polygonatum) all providing early colour but often going summer dormant. A little more persistent are the evergreen hellebores (such as the ‘Ice ‘n Roses’ series) and the Hakone grasses like Hakonechloa macra ‘All Gold’. Sites with open or part shade work well for the often difficult to grow Blue Himalayan Poppy (Meconopsis betonicifolia) or Masterwort (Astrantia major) which makes an excellent cut flower. For late summer blooms look to the Toad Lilies (Tricyrtis) which come in delicate purple, yellow, white and spotted blue flowers.
Anemone nemorosa 'Green Fingers', Astrantia major 'Star of Fire', Blue Himalayan Poppy, Dicentra spectabilis 'Alba', Gold Heart' and 'Valentine', Erythronium / Fawn Lily, Trillium grandiflorum, Hakonechloa macra 'All Gold', Helleborus 'Ice 'n Roses Red', Hosta 'Rainforest Sunrise', Polygonatum multiflorum, Tricyrtis 'Blue Wonder'
The Vertical Element
When it comes to vines I stick to the basics, as most species rated for shade simply stretch towards the sun (leaving a bare base) or refuse to flower. So consider open shade the minimal light requirement under which both Climbing Hydrangea (Hydrangea anomala) and the closely related Schizophragma will thrive, although they are deciduous. Variegated Persian Ivy (Hedera colchica ‘Dentata Variegata’) is a non-invasive evergreen with large leaves generously edged in creamy-yellow; for a closer look at these options, visit my ‘Vines and the Vertical Garden’ blog posting.
Well I hope that gives you some inspiration for your shade garden, just don’t expect all of these options to be in the nursery at one time as they are usually stocked seasonally.
All Images Copyright 2020 MK Lascelle