My garden has shade in the morning and only 4-6 hours of full sun in the afternoon. Should I choose plants suited for full sun because its only exposure is the afternoon hot sun?
Thank you for contacting the Toronto Mater Gardeners.
Plants require sunlight to produce food through photosynthesis. Different plants need different amounts of sunlight to produce a sufficient amount of food to grow and maintain health and vigor. The amount of direct sunlight your garden receives daily directly influences the types of plants that will grow successfully.
Equally important as the amount of sun a plant receives is the strength of the sun’s rays. This varies with the time of day, the season, and the sun’s distance from the equator. Early-afternoon sun is more intense than morning or late-afternoon sun. In Canada, the sun shines most intensely June through September.
Most sources agree that full sun refers to 6 or more hours of direct sunlight. The important thing to note is that length of sunlight does not have to be continuous. Your plant can receive 4 hours of sun in the morning, shade mid day and 4 hours in the afternoon when the sun is the hottest. While many plants require full sun to set buds and flower, some cannot handle the intense heat and/or dry conditions that often come with 6 hours of afternoon sunshine.
If a plant is listed as partial sun it means the plant should receive a minimum of 4-6 hours of sun, the emphasis being on it receiving 4 hours. You may need to experiment with plants that are listed as partial sun. If the plants are placed is a partially sunny area and are not growing well or setting flowers it is probably because they require more direct sunlight.
Partial shade refers to the plants receive 2-4 hours of sun per day. If a plant is listed as partial shade, the plant will need some relief from the intense heat of late afternoon sun.
Your exposure certainly falls in the minimum requirement of full sun and partial sun. The areas which recive 6 hours of afternoon sun I would choose “full sun” plants. Those areas which are receiving only 4 hours of afternoon sun I would chose plants labeled as “partial sun”
The following links are excellent resources : Distinguishing Degrees of Light and Shade, Perennial garden Design, Full Sun, Partial Shade, Full Shade, Understanding the Terms