A Little Something About Sun Exposure

By: Deb Pavlosky
Often times, when we are trying to help our customers select plants, we ask about sun exposure.  What is the sun exposure in the area?  I hear it and say it multiple times every work-day.  And, that’s because it’s important to know.  Before you can select plants for your home landscape/garden, one of the things you have to know is how much sun exposure you get in the areas you want to plant.
It sounds like a simple question, but often times the answer is very complex.  So, I hope you find this helpful…
First things first – Telling us the direction your home faces doesn’t give us the whole answer.  Yes, the sun rises in the East and sets in the West every single day, but we need more information than that your house faces southeast.  Is there a large tree that shades your whole yard most of the day?  Is the bed narrow and along the house and therefore shaded by the house most of the day?  We need you to actually look and see how many hours of sun you get and in what part of the day you get it.  Hours of sun – yes, it matters!

Plant Requirements:

Full sun – 6 or more hours of direct sunlight per day
Full sun + drought and heat tolerant – 6 or more hours of sunlight per day and it can probably handle our mid-day/afternoon summer sun
Part Sun – Between 3 and 6 hours of direct morning sunlight per day or filtered light all day
Part Shade – Between 3 and 6 hours of direct sunlight per day or filtered light all day, but needs protection from intense mid-day sun
Full Shade – Less than 3 hours of direct sun and needs protection from intense mid-day sun.  Many plants requiring full shade do well growing in filtered light, but can not take our mid-day intense summer sun at all.
Filtered Light – aka Dappled light, just refers to sunlight that is “filtered” by a shade tree or other plant or structure from above.  The plant gets some light, but never full-on direct sunlight.
Medium to Low Bright/Indirect Light – this typically refers to houseplants being grown indoors in bright light, but not being hit by direct sunlight through a window.

So, Let’s talk a little bit more about Full Sun:

Full Sun sounds brutal, but this is actually the amount of sun needed by most flowering/fruiting plants.  If a plant is labeled heat or drought tolerant, it can even handle mid-day to afternoon summer sun here!!!  If it’s not, it may still be ok (vegetables and citrus and roses and fruit trees will be just fine), but let’s hope you have full sun in the morning hours.  Some plants (and most people) need a little protection from our afternoon sun in the middle of the summer.  If you put a plant that needs part sun, part shade or full shade in a full sun location, that plant will probably burn and it most likely will not survive long.  So, in the converse, what happens if you put a plant that requires full sun in a less than full sun location?  Well, it will probably still grow, but it may not flower or fruit and may become very leggy as it tries to reach out to get the sun it needs.
So, here in lies the rub – You look at a plant’s tag to get information about the plant.  It says full sun, but does it really mean OUR full sun?  Sometimes not and this is where having a little plant knowledge and savvy goes a long way.  Many plants will grow here that will also grow in zones well to the north of us.  A good clue is to look at the zones on the tag to see how far north it grows.  The farther north the zones are, the more likely full sun really means full sun in the morning hours only here.  The farther south the zones go, the more likely you will have to protect it from freezing in the winter.  Of course, all generalizations are just that.  Ask questions if you aren’t sure.
As a rule of thumb, it’s always a good idea to gradually move plants from one sun exposure to another even if you know they can take it.  Any plant can experience shock if moved from part sun (where you have been hoarding it along the side of your house until you have time to plant it) to full sun.  Make this move gradually, over a period days, to give your plant some time to adjust.
And here’s another thing, it does not matter whether the hours of direct sun are sequential or if the plant gets direct sun at different times throughout the day.  Many times there are structures or trees or fences or something blocking the sun at some point during the day.  But, as long as your plant gets the required hours of sun each day, it does not matter if it gets them all in a row or if the hours of sun are spaced out in some way through the day.
So can you have a single landscape bed that has different zones of sun exposure in it?  Absolutely!  Nothing is perfect in this world and often some landscape beds get more sun along one edge or more shade at one corner because of a tree or other structure.  Yes, you have to take that into account too!
And in the end, sun exposure is just one key factor affecting plant growth and performance – don’t forget about watering, drainage (different than watering), soil type, wind and salt exposure (especially important along the coast), nutrients/fertilizer and age.  Suddenly picking plants for your garden is very complicated.  Well, once again, that’s why we are here to help!