I'm sure someone better at explaining and understanding will come along, but I will try to help best I can in the meantime.

Partial shade and partial sun are more or less the same sort of thing. The real difference might be which an area gets more of, shade or sun. Partial means sometimes, part of the time, the area is sunny, part of the time it's shady. Full sun would be direct sunlight for all or most of the day.

While full shade would mean in shade all day, there are degrees of shade. Your description of the side of your house is deep or heavy shade. I've put a link at the bottom of this post that might help you understand it better. The author uses natural habitats to describe the varying degrees of shade.

If you're trying to understand where you can grow specific plants based on the tags on plants you might do better to research the specific plants. I don't find plant tags to be nearly specific enough. For instance, roses usually say full sun, but you can grow roses anywhere that gets at least 6 hours of sun per day including spots that are in shade a good part of the day if the spot gets the requisite 6 hours of direct sunlight.

For areas that get sun it can also matter what time of day. The sun's light is most intense, strongest, when it's most nearly overhead. The more of our atmosphere the light travels through the more it is filter and weakened. When the sun is nearer the horizon, sunrise or sunset, it's travelling through more atmosphere and isn't as strong. Plants who grow where what sunlight they get is midday are getting more light based on intensity even if they aren't getting the light for as long as plants who grow where the sunlight they get may be hours long but only when the sun is lower toward the horizon.

I hope I haven't made your confusion worse. I'm sure one of the more experienced gardners who might do a better job of explaining will show up to help soon.

Debra

Here is a link that might be useful: Distinguishing Degrees of Light and Shade

Rebecca,

It can be pretty confusing, but I though Debra, and the article she linked, both gave great explanations.

The situation is further complicated, though, by what part of the country you live in and by how intense the summer sunlight is and by how hot the temperatures get. The same plants that would tolerate full sun from sunrise to sunset in July in Pittsburgh, Pennsylavania, for exmple, would not necessarily be happy with the same conditions here. Because our sunlight is so intense and our summer heat is also intense as well, plants here often do well in less sun than you'd expect.

FULL SUN: Full sun is direct, unfiltered sun with a total absence of shade for at least six hours a day. It can mean direct sun from sunrise to sunset but some so-called full sun plants will struggle in true all-day-long full sun in our climate and are happier if they get some shade. About the only plants I've grown that are happy in full sun with little to no irrigation are gomphrena (aka globe amaranth), portulaca and purslane. In a drought year, they may not survive but they'll outlast everything else.

Examples of plants that tolerate full sun in our climate most of the time, and sometimes need irrigation, include coneflowers, rudbeckias, zinnias, coreopsis, heliopsis, angelonia, and some salvias. Honestly though, in my yard, even these flowers are happier if they have a little shade during the hottest part of the day. In some cooler climates, flowers like pansies, violas, and diascia can take full sun all day long, but not here in the hot months. The time of year does have an effect, especially on flowering annuals and perennials....full sun in March is different from full sun in May and full sun in July is different from both of them in terms of how it affects the plants.

PARTIAL SUN/PARTIAL SHADE: These two are often used interchangeably. Partial Shade usually means the area gets no more than 4 to 6 hours of direct, full sun daily. Plants that need partial shade are usually happier if they get their sun early in the day or late in the day but are shaded in the middle of the day. Partial Sun usually means the area gets at least 4 hours of direct sun and 6 is better. Plants that need partial sun also do better if the sun is not mid-day sun, but they can tolerate mid-day sun better than plants that need partial shade. See...it is a very subtle distinction.

FULL SHADE: An area is considered full shade if it gets less than 4 hours of direct sunlight per day, so these areas have very little direct sun and full shade plants can tolerate early morning/early evening sun but not mid-day sun. Full shade plants are usually happy in dappled shade too. Buildings or fences, for example, can cause full shade that is not dappled. Full shade doesn't mean it is a dark area though, just not a sunny one. All plants need to have some light, even if it is only filtered light.

DAPPLED SHADE: These are areas that have a mixture of sun and shade, generally because of nearby deciduous trees. Dappled shade is very similar to partial shade but dappled shade plants do best with very little if any direct sun. When we think of dappled shade plants we think of woodland type plants like wild bloodroot, wild violets or Jack-in-the-pulpit.

HEAVY SHADE: This is as close as you will get to an absence of light. I think of heavy shade as the type of dense shade you get if you are walking through a conifer forest. You will see very little dappled light....just shade, shade, shade. We have an area of heavy shade at the back of our property that consists of very old, very mature Eastern Red Cedars that vary in heigh from about 35 or 40 feet in height to about 60 feet or taller. It is so dark under those trees that virtually nothing grows in the shade under those trees. If you have that kind of a heavy shade area, you really cannot plant anything much under it.

In applying the above to your specific landscape as defined in your original post, I'd say that your shady area between the house and fence is full shade, put probably not heavy shade. Your area that gets sun from noon until sunset (if I remember correctly) is full sun if it gets at least six hours of direct, unfiltered sunlight.

There are plants for every type of lighting except for heavy shade, and there's some that do OK in some types of heavy shade, but if you have heavy shade you have to experiment to see whether anything can grow in the type of heavy shade if you have it. Most folks who live in/landscape in heavy shade have lots of mulch, or prune up the tree branches quite high above the ground to try to turn their heavy shade into full shade or dappled shade.

I've linked a brief article below that I think describes the difference in sun, shade, etc., pretty well in as few words as possible.

Dawn

Here is a link that might be useful: Sun/Shade

Any place that gets sun from noon on, I consider full sun in Oklahoma. Afternoon sun is much stronger than morning sun.

Lisa