Year-Round Gardening: Choose the right plant for the light conditions
When selecting perennial plants for your landscape, most gardeners think first about cold hardiness zones. While that is a great first consideration, the light conditions in your garden are equally important. Plants have evolved to thrive in different light — plants that thrive under the thick canopy of a forest will not do well in harsh sunlight and vice versa.
Proper light conditions are important because the very survival of plants requires the right conditions for photosynthesis. Photosynthesis is the conversion of water and carbon dioxide into carbohydrates. Sunlight is the energy source for this process. If the light is not right, the plant will not thrive.
Plants vary widely in terms of light needed and tolerated. Shade plants are anatomically adapted to be more efficient at photosynthesis in limited light and feature thin, large surface area leaves. By weight, they contain more chlorophyll than their sun-loving counterparts. Think about plants like hosta, coral bells and ferns, plants valued for their big, colorful, foliage. Sun-loving plants in general, have thicker but smaller leaves. The smaller leaf surface results in less water loss during the hot part of the day. An extreme example of this adaptation is cactus: The leaves are thorns. More common examples are succulents, roses and penstemon.
Plant tags usually indicate how much direct sunlight the plant requires each day:
Full sun is 6 or more hours.
Part sun is 4-6 hours.
Part shade is 2-4 hours.
Full shade is 2 hours or less.
The sunlight should be measured in late June, around the summer solstice.
To evaluate your garden, on a sunny day when you will be at home, observe the planting site once each hour, starting in early morning, and note how much sunlight is on the site. By the end of the day, you will understand the sun conditions.
Pay attention to what time of day the garden is sunny. Shade plants may tolerate some sun in the early morning but wither under the hot afternoon sun. Likewise, plants that are sun loving may be fine with morning shade if they get hot afternoon sun. Plants that get too much sun can appear bleached or even scorched. Plants that do not get enough sun may not flower abundantly and can look spindly and weak.
Pay attention to sun conditions as your landscape matures. Trees that cast little shadow when planted will shade much larger parts of your garden when mature. Likewise, if trees are removed, a shady area can be suddenly sunny. If you are unsure about a plant’s needs, do some research before you buy. Be as specific as possible when gathering information, using the genus and species of the plant. Common names can be imprecise. It is worth the effort to ensure the plant’s success in your garden.
Submit gardening questions to csumg2@elpasoco.com or call 520-7684. The in-person help desk is open 9 a.m.-noon and 1-4 p.m. Mondays and Wednesdays at 17 N. Spruce St. Find on Facebook at Colorado Master Gardeners – El Paso County.
Plants with large leaves and interesting variegation are great choices for shade gardens. Even when not in bloom, these plants provide interest and texture. The plant pictured is Pulmonaria “Shrimps on the Barbie.”