Sun Exposure

By Diane Lehr

UC Master Gardener of El Dorado County

This article appeared in the July 31, 2024 Mountain Democrat

I am sitting here, pen in hand, writing an article about sun exposure and our community is in day ten of a heatwave. Yes, this could be an easy article to write because too much sun is on everyone’s mind. I am going to tackle the effects of too much sun on plants, the possible prevention steps for plants, and for us as insatiable gardeners.

Plants do need sunlight to grow, it is part of the equation of sun, water, and soil. The amount of sunlight can be based on the genus of the plant. Cactus will tolerate more sun than a more delicate hydrangea, which I secretly call “Hydrate me.”

When deciding where to plant, read the tags or labels placed with the plant. Full sun plants need at least six hours of direct sun daily. Part sun plants thrive with between three and six hours of direct sun per day. Part shade plants require between three and six hours of sun per day but need protection from intense mid-day sun. Full shade plants require less than three hours of direct sun per day. Also on the plant tag is the USDA Hardiness Zones in which the plant can thrive. You can find your Hardiness Zone here: https://planthardiness.ars.usda.gov You just need to enter your ZIP Code and you will find your Hardiness Zone.

Periodically, look at your garden from sunup to sundown to see how the sun travels over it. Are there trees, walls, or gazebos that may be casting shadows on your garden? Know which parts of your garden get only morning sun, or those areas that are in full sun during the hottest part of the day.

The danger to plants from too much sun has various symptoms including sunburn, sun scald, wilting, leaf scorch, leaf tip burn, and bud drop. All these issues can be caused by excessive heat and/or lack of sufficient water. To use water wisely, water in the very early morning or after the sun goes down for the maximum benefit and to lower the loss of moisture from evaporation. Shade cloths are effective tools to protect your plants from the too-bright sun and keep the surrounding soil cooler, helping it to better retain moisture. Consider the type of mulch you use because inorganic mulches such as stone and gravel retain heat more than organic mulches such as bark and chips.

Most importantly, take care of yourself in the heat. Wear a wide brim hat and one that has a flap to cover your neck. Use a broad-spectrum sunscreen with a sun protection factor (SPF) of 15 or higher. Wear long sleeves and long pants to protect you from sun exposure. Several clothing manufacturers make light weight UV clothing that repels the sun’s harmful effects. Stay hydrated and garden only in the early morning or early evening.

We will get through this heatwave, and by the time this goes to print, perhaps we’ll be praising the 90s!

Master Gardener classes are offered monthly throughout the county. You can find our schedule at: mgeldorado.ucanr.edu/Public_Education/, and recorded classes on many gardening topics here: mgeldorado.ucanr.edu/Public_Education/Classes/

The Sherwood Demonstration Garden is open through Spring and Summer on Friday and Saturday from 9:00 - Noon. Please check our website for further information about activities at the Sherwood Demonstration Garden at: ucanr.edu/sites/EDC_Master_Gardeners/Demonstration_Garden/

Have a gardening question? Master Gardeners are working hard to answer your questions. Use the “Ask a Master Gardener” option on our website: mgeldorado.ucanr.edu or leave a message on our office telephone: 530-621-5512. We’ll get back to you! Master Gardeners are also on Facebook, Instagram, and Pinterest.

For more information on the UCCE Master Gardeners of El Dorado County, see our website

at mgeldorado.ucanr.edu.