Many plants, especially lawn grass, flowers, roses, vegetables, fruit trees, and conifers (needle-leaved evergreens) thrive in bright sun, which provides abundant energy for growth, flowering, and fruiting. But some plants, particularly those native to forests and glens, need shadier conditions. Learn the sun requirements of any plant you intend to grow so you can put it in the right place.
Assessing Light Conditions
Do you have a sunny backyard or one that is mostly shaded by trees? How about your front and side yards? You may have never looked that closely, but before you plant it's important to carefully assess the type of light conditions you have in each part of your yard. Here are a few tips to help you determine light conditions:
- Watch how sunlight and shadows hit the ground to determine how much shade exists during the growing season under deciduous trees (those that drop their leaves in fall). This test helps you determine which shade-loving plants will thrive there.
- Full shade is found under thickly branched trees or evergreens. A garden that's located here will receive little or no direct sun and remain gloomily lit. Only a limited number of plants are suitable for this situation. You should choose flowers and ferns with evergreen leaves.
- Partial shade is found under trees that allow sunlight to penetrate through the canopy and dapple the ground throughout the day. A garden grown under a lightly branched honey locust tree would fall into this category. A larger selection of plants are capable of growing under these conditions than in full shade.
- Light shade is found in places where plants are in direct sun for a portion of the day. This could be found in a garden under mature trees with tall barren trunks. The sun can shine in under the high leafy canopies. Light-shade conditions also exist on the east or west side of a wall or building. Here you can grow many shade-loving plants as well as shade-tolerant plants, which are sun-lovers capable of growing moderately well in light shade.
- Providing a minimum of 6 to 8 hours of direct sun a day is sufficient for most plants that need full sun. The term "full sun" doesn't actually mean plants must be in bright light every moment of the day, only most of the day. The minimum must be met, however, even during the shorter days of spring and fall for perennials, trees, and shrubs.
Lighten Up: Making the Most of the SunNo matter what the plant, it will need at least some sun to help it grow. If your yard is mostly shady, take note of the following tips to help you shed a bit of sunlight to the plants in your garden.
- Try exposing flowering shade plants to a half day of morning sun to encourage better blooming. Extra light can also keep the plants more compact, tidy, and self-supporting. Plants for Sunny Conditions Some people have the problem of just too much sun in their yard, which surprisingly enough, can harm a growing plant just as much as not enough sun. Following are some plants that do well in very sunny conditions.Annuals: portulaca, gazania, gerbera, marigolds, zinnias, dahlias Herbs: lavender, thyme, sage, rosemary
- Grow sun-loving spring bulbs and wildflowers beneath deciduous shade trees to make the most of the sun before the tree leaves emerge. This is a great strategy if you have a shady yard and therefore have trouble getting flowers to grow during summer and fall. Crocuses, squills, Spanish bluebells, daffodils, wind-flowers, glory-of-the-snow, and wildflowers such as bloodroot, squirrel corn, and other local natives thrive in spring sun. When tree leaves emerge and the setting grows dark, many of these spring growers fall dormant and lie quietly below the ground until spring sun arrives again.
- Paint a dark wall white to reflect more light onto plants. Just like the silver solar reflectors used by sunbathers to intensify their tans, a light-colored wall reflects additional light onto nearby plants. Similarly, using a mulch of white pebbles, sand, or gravel will reflect light up through the bottom of plants, a technique often used in gardens of Mediterranean herbs or silver-leaved plants that thrive on plenty of sun.
- Limb-up trees or remove smaller, scraggly, or unwanted saplings and brush to brighten a densely shaded spot. Tall, mature shade trees can have their lower limbs removed (a heavy job requiring a professional arborist) to produce light shade. For even more light, arborists can thin out overcrowded branches in the canopy, leaving some openings in the foliage for sun penetration.
Removing unwanted tangles of young trees, wild shrubs, and other woody growth is a project you can do yourself. Look for self-sown seedlings around trees such as maples, oaks, ashes, and elms. Crab apples will send up vertical sprouts called suckers, turning the tree into a shrub. Get a pair of long-handled pruning lopers to trim out the smaller growth and a pruning saw to remove larger trunks. When finished, you can admire the newly revealed shape of the tree trunk and the ferns, hostas, and other shade plants that can grow beneath it. Be sure not to overthin; you should leave enough saplings to replace older trees as they die.Prune low-hanging branches on a sunny day so you can see how the light changes. This way you can watch the shade lighten. You also can keep an eye on the shadows, which will dance from one side of the tree to the other, changing with the time of day and position of the sun. Their silhouettes can be a beautiful part of the garden, especially in winter when the dark shadows stand out on the white snow.Do not prune oaks in summer. Even though this may be when you are anxious to lighten shade the most, it will make your trees susceptible to oak wilt disease. Prune, instead, in late winter.Learn which side of the garden is best for your plants and get help with your indoor plants in the next section.
Sun Exposure and Indoor Plants
The right amount of lighting is crucial for plant health. There are certain factors to consider regarding direction of the sun's exposure, as well as how to care for your indoor plants.
Consider differences in sun intensity when planting on the east and west side of shade-casting trees or buildings. Even if east- and west-facing sites receive the same number of hours of sun, they will not produce identical results.
- Gardens with an eastern exposure are illuminated with cool morning sun, then shaded in the afternoon. They are ideal locations for minimizing heat stress in southern climates or for plants such as rhododendrons that can burn in hot sun.
- Gardens with western exposure are shaded in the morning and drenched in hot sun in the afternoon. Sunburn, bleaching, and sometimes death of delicate leaves can result, especially in warm climates and when growing sensitive young or shade-loving plants. Afternoon sun can also cause brightly colored flowers to fade. However, the west side of a building is the ideal place for sun-loving and drought-tolerant plants.
Indoors When growing potted plants indoors, supplement natural light with fluorescent or grow lights. Sometimes in winter the weather may be cloudy for days, even weeks. This creates problems for tropical plants, potted flowers, and even foliage plants that need light to remain healthy. The solution is to hang a fluorescent shop light directly over your indoor plants. Special grow lights or full spectrum bulbs (formulated to produce light wavelengths that plants need most) can be used in place of fluorescent bulbs for spectacular results with flowering plants. For extra-easy maintenance, plug the lights into an automatic timer, then set them to turn on for 14 to 16 hours a day and off again at night.No matter how intense or dim your lighting source, or which direction it's coming from, you can still grow beautiful plants with the right know-how.
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