Many factors affect the health of landscape plants. One of the most confusing is light intensity – the amount of sun or shade a plant needs for optimum vigor. How do you determine if a plant you’re thinking of buying will like a certain light condition?
Nurseries attach tags to their plants that provide general information for healthy growth. You may need a plant suitable for your home’s sunny south-facing entrance, and the plant tag says your plant loves full sun. Or you might want a plant for a shade garden you’re planning to install under a mature water oak. The tag says your plant thrives in deep shade.
But what if you want to plant in partial shade? Or part sun? Just what do these terms mean, and how do they affect your decision to place your plant in a certain position?
Seeing the Light About Your Plant’s Light Requirements
An area blessed by full sun means it’s exposed to direct sunlight for at least 6 hours per day. If a wall of your house faces south or west, and there are no trees casting shade on the wall in the middle or late afternoon, you can think of this area as full sun. Western and southern exposures get more light and heat up fast.
Light filtered through leaves (or through a screen like a trellis) is considered partial sun or partial shade. Plants here don’t want or need direct sun. Early morning light (less harsh than that hot western exposure) can be included in the partial designation. Generally, more than 3 hours of sun and less than 6 can be classified as partial sun or partial shade.
Full shade means an area receives direct light less than 3 hours a day of direct sunlight. This condition may occur in a woodland environment, on the north side of your house, or in the narrow side yard between two buildings. Many plants tolerate full shade, but not that many thrive there, so choose your plant wisely.
Full sun loving plants may grow perfectly well in less light, but their flowering or foliage growth will suffer. A plant that thrives in less light might be a better choice. Conversely, if a shade lover gets too much sun, leaves and bark may burn.
Light conditions aren’t static – they’re always changing. Latitude makes a difference. A plant that needs partial shade in the hot south may do just fine in full sun in Washington or Oregon. And don’t forget to factor in the time of year. Due to the angle of the sun, shadows are longer in winter than summer.
When placing your plants, keep in mind that a full sun environment in the summer could turn into a partial or even full shade environment in winter. Familiarize yourself with the various patterns of sun and shade in your yard throughout the day, and factor in the change of seasons. That way, you’ll be sure to match the right plant to its ideal light needs.
Whether you’re choosing a plant for full sun or full shade, or conditions somewhere in between, learn the cultural needs of the plants you want to use before purchasing or planting them. Soil moisture plays an important role. Adequate moisture will increase a plants tolerance for sun.
Take the time to learn the sometimes subtle differences in your yard’s light intensity before you install your landscape. Your plants will thank you for it.