Conservation Specialist
copyright 2010
LIGHTEN UP PLEASE!
I know it is frustrating to identify how much shade you are dealing with- but don’t take it out on me-instead let me help you understand why it is so complicated- but trust me-shade gardening can be wonderful!
First question: What kind of shade do you have and and how much?
Not all shade is equal! There is many shade definitions, factors and interpretations. Although some terms are used interchangeably, they may not mean the same for you! Just the way air temperature in the shade can be a factor like the way full sun in Oregon is not the same as full sun in New Mexico, the amount, the reason, the coolness and even the warmth of the shade can also be a influential factor!
Newbie gardeners and “transplant” gardener unfamiliar with Missouri’s hot summers, fluctuating heat, high humidity and warm shade can easily get confused. Terms such as filtered shade, partial shade, partial sun, filtered sun, filtered shade, open shade and dense or heavy shade can be overwhelming! My best advice- check your source, look for definitions in the website, check the catalog index you are reading or speciality books usually discuss the topic in lenght in the introduction. When in doubt- ask whoever you are talking to-in this case ask me what I mean. This is how I define all the shades of "shade" when I talk about it!
First, it is important to note that shade is not usually constant. Lighting changes with the time of day and from season to season. Shade is also dependant on its source. Any alterations to the site over time can also affect the plant’s performance. As trees grow they cast more shade as the size of the tree’s canopy expands. Simple construction activities also may impact sun light to some degree. Even a companion plant’s maintenance care such as heavy pruning on a large shrub can temporarily change the lighting and water requirements on it and the other neighboring plants.
Green spaces that might be in full sun part of the year may become heavily shaded as the season progresses. Trees leafing out or annual or perennial vines grow and block light. Light is also influenced by the lay of the land (topography). Comparatively, a south-facing slope receives more light than a north-facing slope.
Types of Shade
Partial Sun / Partial Shade are terms that are often used interchangeably to mean 3 - 6 hours of sun each day. The emphasis is still the light level and how it affects a particular location. This is a solid shade that moves with the sun such as the shade from a building or solid structure. A plant listed as Partial Sun usually has a low tolerance for hot sun. The emphasis is put on the amount of sun necessary for good performance without looking worn out in summer heat. It usually means morning sun-afternoon shade is best. Full sun may not be an option for a plant listed as “partial sun”.
Also if a plant is listed as "Partial Shade" or Only Partial Shade"it usually means it is a sun plant that tolerates some shade and still performs well. This is a condition that usually occurrs because of a nearby tree or planting it on the east side of a building. Flowering may be less but foliage may look better mid-season. Please note: Evening Sun does not exist as far as plants are concerned! Sun after 4 pm is at such an angle that it is basically considered light and not a significant contributor to the garden except for viewing purposes. Sonsider such a site as Heavy Shade.
Filtered or Dappled Sun/ Shade / Filtered Shade (Dappled sunlight, Dappled Shade, High Shade ) is suitable for growing many plants --- even plants that prefer full sunlight such as daylilies and iris. It is the sun that makes its way through the branches of deciduous tree and has relatively high intensity. The sunlight and shade patterns are constantly changing from minute to minute during the day. This occurs frequently where trees are limbed up very high or have fine foliage that casts a light lattice work of shadows. This light usually is of high enough intensity that many sun plants will still perform fairly well. Dark colored daylilies and iris hold their color better in this light without getting “slick” or shinny in the afternoon heat.
There are many Missouri natives that perform well with this type of sunlight To see an example of this type of shade observe the light levels under river birch or honey locust trees. Since this shade is rarely fixed throughout the day, spend some time watching the way the light and shadows fall throughout your garden space and use this "light play" to create focal points. Stake out those bright pockets that are the most constant through the course of a day and plant them with glossy, light colored or reflective foliage. This can significantly increase the impact of your garden. For instance, if light catches a particular corner in the afternoon, brighten it further with a yellow Hosta. Deeper shade pockets can be drawn closer with the use of variegated white foliage. Dappled / filtered shade is a wonderful tool for playing with coarse textures and bold leaves. Usually filtered shade does not receive full sun light for any length of time between 10 am or before 3 pm. Frequently light levels are low enough that a camera with an automatic flash will choose its flash option in this light.
Open Shade
Open shade occurs where there is an open expanse where are there are no trees overhead to block sunlight but the plants are in the shade due to the overlap of shadows from multi-level buildings in campus situations. Open shade is well lighted but does not receive direct sunlight- it can be very dry because of rain shadows and post construction compacted soil.
Deep/ Full shade
Deep shade is the most restrictive type of shade. It has less than 3 hours of direct sunlight all season. It may not have any sun and can be very dark. In extreme situations there aren't many plants, except mushrooms, that can survive in very deep shade. You may be able to lighten up full shade by having a few lower tree branches removed by a certified arborist. This is a stress on a tree but will allow more sunlight to get through. I suggest working with existing light levels instead of altering the site.
Deep shade is found in heavily wooded areas and in landscapes where large evergreens or broadleaf deciduous trees such as Maples, Oaks and Hickories occur. Deep shade can also occur in a narrow spaces such as side yard on the north side of the house when another home or building is located close by. This can also be a recessed entry way on the north side of your house.
Other Shade factors
Many shade plants developed in woodland situations, where the soil tends to be rich and slightly acidic from the decaying leaf mold. Because the buildup of decaying plant debris is not removed in natural woodlands, there is always a nice layer of mulch keeping the soil temperature constantly cool and feeding the soil with a steady supply of nutrients. When trying to create your own shade garden with woodland plants, try to recreate these conditions, paying special attention to providing rich soil and organic mulch.
Many shade plants produce large leaves to take best advantage of the low light level. Some shady sites can be quite dry so these bigger leaves can suffer from moisture shortages. Next time you walk in the woods notice how many plants grow in the direction of the strongest light. Sometimes one side of the plant will be thick and full while the other side will be thin and sparse.
Create Tree-mendous Opportunity
Once you understand you might be dealing with dry shade, compacted soil, constant or transitional light periods and a reduced organic cycle you may not be sure you want shade. Believe me –you do want shade and If you don’t have shade- consider adding structures to create a shade garden. Don’t be discouraged by a lack of established shade trees. You can use manmade structures to create your own shady nook. Pergolas and arbors covered with vines will provide enough shade to garden underneath. You could even use a trellis as a wall to cast shadows of shade onto an ideal spot.
Problems Associated with Shade Gardens
Shade gardens are no more work than sunny gardens. Most shade garden plants prefer a moist soil, so you will need to water regularly and mulch. Mossy situations may be telling you more than you think and can be remedied. Be on the lookout for fungal diseases that can develop because of the damp condition. To offset this, don't plant too closely and allow for good air circulation. Snails and slugs will be attracted to the cool, moist shade. Delaying mulching till first of June will help. Trapping and hand picking will need to be done throughout the growing season. (On the plus side, there are fewer weeds in shade, because the lack of sunlight inhibits germination)
Designing a Shade Garden
Design is always a matter of personal taste, but shade gardens lend themselves to understatement. Focusing on foliage and texture rather than flower color, will give you the most natural effect. While there are many plants that will flower in shade, colors will be more muted than in a sun garden. White flowers and variegation will add brightness to a shade garden, however yellow variegation tends to be less pronounced when grown in shady conditions. Delicate foliage and flowers can be appreciated in shade while a plant with a strong form and bold leaves will stand out more clearly.
Community Effort
A natural woodland is layered with plants: a tall canopy of trees, under story trees and shrubs and then a herbaceous plant layer. You may not have room to completely recreate this, but keep this in mind as well as remember it is novel to have single specimens in nature, so grouping and massing like a sun garden will feel more natural as well. The real key to shade gardening success is choosing plants that will thrive in the shade you have.
Shop Talk
Most nurseries group shade plants together, making it easier to make the right selections because they should know what works in this particular region. If you don’t know- don’t be afraid to ask. Catalogues are confusing because a sunny day in Wisconsin isn’t the same here! There are also several plants that might grow in sun, which will tolerate partial shade. They may not grow as quickly or bloom as profusely as in full sun, but they are worth keeping in mind when choosing shade plants.
Best Tool- Your Shadow!
New garden care: New perennials need to be watered during their first and second year as well as during dry spells. Also, walk the area frequently and remove weeds as soon as you see them. It will be easy now that you have cleared and loosened the soil. Chemical control is rarely needed in most situations.
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