Planting in Dry Shade
Posted: November 20, 2012
Most of us who live in suburban areas, and try to plant a garden under a tree, meet limited success. The reason our garden doesn't grow well can usually be attributed to dry shade. What exactly is dry shade?
Have you ever been outside when a sudden shower has you running for cover? If you run under a tree, you notice you don't get nearly as wet. You are benefitting from the umbrella-like canape of the tree. Good for you, but bad for the plants trying to grow there. Add to this the thirsty roots of that same tree drinking up available water before the smaller plants have a chance, and you begin to understand what may be the problem with your struggling garden.
Adding organic matter to the soil is one of the best remedies for almost any gardening problem including this one. But, be careful. Piling soil on the ground under a tree can smother its roots and kill the tree. Likewise, excessive digging under a tree can severely damage its root system.
You can, however, safely add a two to three inch layer of compost or mushroom soil to the soil beneath the tree. Then select small plants, so it is not necessary to dig deep holes. That way you will disturb the tree roots as little as possible. Keep the garden well watered, and the next year add three more inches of soil amendment.
There are some plants that are better at accepting dry shade than others.
However, for your garden to really thrive, you will always have to water and fertilize it more regularly than you would most other gardens. Not only does your tree drink up the lion's share of the water, it also gobbles up the nutrients. I like to use a natural fertilizer because, although it's true that plants can't tell the difference between natural or chemical, the natural fertilizer actually builds your soil where the chemical does not.
An excellent idea for caring for a shade garden is to rake the leaves off of it and shred them in the fall, then put them back on the garden. Leaves falling onto your garden in the fall can become wet and matted and actually smother your smaller plants. But if you rake them out of the garden using a flexible rake (I use a small hand-held rake called a "Yard Butler"), then shred them (this can be done with a lawn mower with a bagger), you can apply them safely back onto the garden area like mulch. This practice will feed your plants, protect them from heaving, and help retain soil moisture.
If leaves fall onto your lawn, it is not necessary to rake them. Run over them with your non-bagging mulching mower and let the shredded leaves scatter over the grass. Do this regularly as the leaves fall, and you can digest up to 18 inches of leaves with no raking. Your lawn will remain healthy and thankful for the extra nutrients that the leaves provide.
Looking for a suggestion for a good looking plant combination for your shade garden? One of my favorite shade plants is Brunnera 'Jack Frost' . This year it was chosen 2012 perennial plant of the year. It is a large leafed perennial resembling a hosta, but it has silvery leaves with dark veins. Pair it Heuchera (Coral Bells) 'Silver Scrolls' which has a silver leaf with red veining, and deep red highlights. I love the 'Silver Scrolls', and it is less expensive because it is an older cultivar.
For a garden with a green and gold theme, try combining Hosta 'Sum and Substance' with Variegated Solomon's Seal along with the Heuchera 'Georgia Peach' for a deep red accent.
Ground covers also work well in your shade garden. Creeping Jenny (Lysemachia nummularia, 'aurea') is a bright yellow ground cover that stays close to the ground. It can really brighten up the shade or the sun garden. Another wonderful bright yellow ground cover for the shade is Vinca Minor 'Illumination'. It has bright yellow leaves which are edged in green. I love Spotted Dead Nettle as a ground cover in the shade. It has a variegated leaf with a pink or white flower in May. Keep in mind that anything called a "ground cover" gets its name because it spreads and multiplies. They all need to be restricted at some point.
Here is a list of additional plants that will tolerate dry shade. Lenten Rose, Lily of the Valley, Columbine, False Lamium 'Herman's Pride', Liriope, Pulmonaria (Lungwort), Bergenia (try 'Lunar Glow'), some Hostas (Sum and Substance is the best I have found so far), Epimedium, and Nandina Domestica. For vines try: Climbing Hydranges, and Golden hops.
This list would not be complete without including bulbs. Bulbs need sun to bloom, but when planted beneath deciduous trees, they bloom early before the trees leaf out in the spring so they do get their sun. Once the bulb completes its photosynthesis process after blooming, it actually prefers dry soil all summer.
My final suggestion for dry shade gardening is the use of pots. A couple beautiful pots placed among the ground cover in the shady area makes a very lovely picture. Two advantages are that you just have to water the pots, not the whole garden as often, and you can enjoy plants in the pots that won't tolerate the dry shade. Begonias, Caladiums, and Coleous are all good choices for the shade in pots. Going back to the idea of the Brunnera and Heuchera, I would add a bright blue glazed pot containing the red flowers of Dragon Wing Begonia mixed with Licorice plant (Helichysum). Take a trip to your favorite greenhouse, and they will point out some excellent shade flower suggestions.
Barb Mrgich is a Penn State Extension Master Gardener from Adams County. Penn State Cooperative Extension of Adams County is located at 670 Old Harrisburg Road; Suite 204, Gettysburg. Call 334-6271.