Over the course of each and every season, a myriad of gardening questions are thrown my way. I am always happy to answer them all because that it is what I truly enjoy – helping in any way I can, attempting to steer each unique gardener towards unbridled success. There are no black thumbs after all, just duller green ones that require some polishing to bring out the hidden shine. One consistently common issue that many gardeners inquire about is dry shade. More specifically, what to plant under established trees and in turn how to get plants established successfully in those drier, shady garden locations.
Planting anything in an established landscape can be a bit more challenging, especially in and around the root zones of trees. Coming out of our drier summer months, soil can lack any and all moisture. First and foremost we need to rehydrate these areas, incorporating compost or similar amendments to get the ground ready for fresh planting. A soaker hose can help with this, as can a simple sprinkler. Water may run off the soil surface to start, but as this hydrophobic soil absorbs moisture, water will eventually start to penetrate. This is not a 15 minute thing by any means, I am talking soaking for hours if needed. Doing this will also prepare this area for the future as you will be soaking these dry shade gardens infrequently season after season, year after year, particularly in the dry summer months. Even with rain, garden locales under trees (or for me under eaves) don’t get to soak up much of that rainfall. Monitoring moisture in these areas is critical for the establishment of plants and by utilizing drought tolerant plants and natives, less and less irrigation will be required over time.
Once your area is rehydrated, it is planting time. Be sure to dig holes twice as wide and deep as the container they come out of and amend your native soil with up to a third of compost. If this is an established garden, especially under a tree, be careful digging near roots. Cutting some to create a pocket to plant in is perfectly fine, but avoid cutting any major roots that anchor your tree. I have done this many times, and at worst maybe the spot you picked gets shifted a bit to avoid any major roots. Sometimes smaller (like 4-inch, quart or gallon size plants) are not only easier to get holes dug and started in these tougher situations, but they are also more budget friendly. Utilize a good organic transplant fertilizer to help their root systems to establish quickly and mulch them as well to conserve water. When planting under trees, be sure not to pile mulch on that tree’s trunk, instead keep the soil level the same and then feather that mulch out deeper around your new specimens. Drought tolerance comes with time, so keep them watered until established! When feeding these plants down the road, applications of the appropriate granular organic food each March and June will help, especially under trees. Always keep in mind that the tree is going to grab much of the water (and food) that is provided under it.
After looking around your landscape, note areas that are mostly shade and that tend to stay very dry. How much sun does that specific spot really get? Is it deep dark shade? Or is it getting filtered light, like the typical woodland setting? Maybe it gets a blast of sun when it is lower in the sky, like early morning or late evening? How far is that tree limbed up, or should I prune it up even higher? Knowing exactly how long and when the sun will hit a location will be key to matching the right plants to their right places. A few suggestions for drier shade and part shade gardens are discussed below…
Shrubs for dry shade: If you have deep dark shade, taller shrubs like Japanese Aralia (Fatsia japonica cvs – 6+feet) and Japanese Laurel (Aucuba japonica cvs – 6+feet) can both add dramatic impact with foliage color and fend for themselves at the same time. On the smaller side, native forms of Oregon Grape can all take a bit more sun, including Mahonia aquifolium (4-feet), Mahonia repens (<1-foot), and Mahonia nervosa (<1-foot), depending on your desired height. There are also the super easy types of Sweet Box, Sarcococca ruscifolia (6-feet), Sarcococca confusa (4-feet), and Sarcococca humilis (<2-feet). These are all low maintenance and provide excellent winter blooms with fragrance. Even Daphne, which prefer it dry and struggle in wet, can thrive under trees with some sun – especially Winter Daphne (Daphne odora cvs. – 4-feet). Another attractive shrub that can take a bit more sun and thrives with drought is Leucothoe (3-feet or less), a lovely evergreen with nice foliage color that intensifies over the winter. These are great space eaters in the garden, bushy and easy to grow in partial sun. Another useful (and deliciously edible) native shrub for understory use is Evergreen Huckleberry (Vaccinium ovatum – 4-feet), which has lovely red new foliage and excellent dark berries to snack on.
Perennials for dry shade: There are lots of drought tolerant perennials to choose from for shade or partial sun, including a few that stay evergreen in our climate. Lovely winter blooming Hellebores (<2-feet) are at the top of my list, with lots of options for foliage and flower available. Coral Bells (Heuchera cvs), Foam Flower (Tiarella cvs) or Heucherella (a cross of the two species) offer bright foliage color options and blooms for most of spring, summer and fall. In shade the limey, variegated, yellow, and orangey ones all tend to thrive and stay evergreen. Bishop’s Cap (Epimedium cvs) are some of my favorite low maintenance perennials, slowly spreading (under a foot tall) to cover up some ground. They have lovely spring foliage color and turn bright reds and burgundy in fall. This color holds through winter and then they bloom (color varies by variety) in early spring, adding even more interest. This plant to me is the perfect choice for mass plantings in dry strips and under trees. I still have these in both situations in my own yard and they continue to grow nicely with minimal care or water. I also use plenty cultivars of Hostas, as you can add bold foliage, big or small, in a lovely array of color combinations and shapes. These exhibit excellent drought tolerance as well for a true perennial in these shade or partially shaded areas.
Groundcovers for dry shade: There are a number of good groundcovers that will eat up some space if that is the goal. Natives like Bunchberry (Cornus canadensis), Salal (Gautheria shallon) and Redwood Sorrell (Oxalis oregana) are acclimated nicely to our dry summer weather. You might also investigate colorful options of Carpet Bugle (Ajuga cvs.) or even Spurge (Pachysnadra sp.) which are both evergreen. Perhaps a bit harder to find is Creeping Honesysuckle (Lonicera crassifolia), a fun specimen that is evergreen and sports nice cream/yellow flowers followed by berries for wildlife. One more that I adore is Inside Out Flower (Vancouveria hexandra), a beautiful shady native that has done very well in my landscape in deep shade under old Rhododendrons. Any of these groundcovers can fill in some space under trees, provide texture and color, and help keep your weeds at bay.
Walk around your yard and see where you may have some dry shade, and ponder what you would like to get established in these areas. I am bringing this topic up now as we close in on fall, mainly because autumn (with its warm soil and impending rainfall) to me is the single best time to plant anything. This is even a more important time for those difficult areas; slopes, underneath trees and those back corners where it is challenging to get the hose to over the summer. Once rains begin in autumn, Mother Nature is there front and center to aid in getting our new treasures established. A visit to the local garden center and a conversation with a Certified Professional Horticulturist will help you with both planning out your drier shade gardens and selecting the perfect plants to thrive in them. I think you will be surprised at the botanical options for these areas, and with a little work to get them planted properly you can achieve success. Replace that half dead grass, those weeds and the struggling plants with colorful, attractive specimens for dry shade that will make you proud and thrive for years to come.
