Marin IJ Articles
|November 4, 2000|
by Maggie Agro
Every garden has some shade. If your home has a north side, or if the sapling you planted is now a mature tree, you have shade. And no matter what folks tell you, shade is a good thing. Many plants thrive in the shade, and it's that lush, cool respite from the heat that draws us to a woodland setting. Muir Woods is always cool and teeming with vegetation.
A lot of people claim that their plants always die in the shade, but the shade isn't the problem, it's the soil. If the shade is under trees, remember that a tree's roots are hungry and will devour all of the nutrients and water. Soil around trees often becomes hard and lifeless as a result. You've got to revive and replenish that soil with lots of humus, decomposed organic matter. It can be compost, sterilized and well-rotted manure, shredded leaf mold (last year's leaves), peat moss, and decomposed kitchen waste like coffee grounds and vegetable waste.
Think about the floor of a forest with the leaves and decaying matter that cover it. Humus lightens the soil and holds water and eventually becomes part of the soil. It's a good reason to start a compost heap if you haven't already. If you get leaf mulch from your city's recycling plant, be sure to let it sit as compost for at least 3-4 months before you use it, in order to kill any weed seeds and roots that it might contain.
A good way to determine if your soil needs humus is to dig a hole about 10 inches deep and fill it with water. If the water isn't absorbed almost immediately, your soil is either hard-pack clay or already too wet. The cure is the same for both. Add plenty of humus, try to work in at least one inch of the present soil and try not to walk on the area. If it is a walkway, install stepping-stones. Another way to tell if your soil has enough humus is to look for the presence of worms. If it's without worms, you need more humus.
You can also buy a home-testing kit to determine the acidity and nutrient level of your soil. Directions are included and will tell you that neutral is a pH of 7. Below 7 is acidic, sometimes called sour. Above 7 is alkaline, sometimes called sweet. Shade should fall between 5.5 and 6.5. Leaf mold or composted pine needles can acidify soil and lime can sweeten it.
A shade garden should be damp all of the time. An underground drip irrigation system or a soaker hose will pay off in the long run. Over time it will conserve water because it puts the water at the roots and minimizes runoff. It will prevent wet flowers and foliage, a good breeding ground for disease.
You can modify light by careful pruning of trees to let the light through. You can cut limbs that grow too close to the ground to provide more light and enhance air circulation. Prune shrubs from within to thin out the middle and allow air to circulate and light to penetrate.
If you plant under trees, try to plant near the drip-line, as roots may be too large nearer the trunk. Don't rototill because tree roots grow close to the surface. Cutting smaller roots won't hurt, but use a sharp spade or lopping shears to avoid tearing them. Another important consideration is the type of shade that you have. There are many degrees of shade:
When you look into purchasing plants or plucking them from the wild, you will find that the foliage and overall form of shade plants is their strongest feature. When making your selections, vary leaf shape and color. In deep shade, try using silvers and light greens to brighten up dark spots. Give the eye a tapestry of shape, texture, and varied greens. When you look into a well-planned shade garden, you discover the play of broad leaves with small leaves, round with angular, light with dark.
There are some wildflowers that work well and, usually, reproduce themselves. The only drawback with wildflowers is that most die back in the winter. Some good choices are: Solomon's seal, baneberry, bishop's cap, Dutchman's breeches, fringed bleeding heart, bloodroot, iris cristata, jack-in-the-pulpit, lady's slipper, trillium and many varieties of violets and wild geraniums, and wild ginger.
Q. Where can I find specific information on shade plants?
Tip of the Week
This article appeared in the Marin Independent Journal on November 4, 2000.