Often when I ask people if they get full sunlight on their plants, they respond, "Most of the time." Full sun literally means from sun up to sun down each day. Full sun plants will generally "get by" with 6 or more hours of direct sunlight but this means that the remainder of the day is spent in some state of shade.

So, any site in our landscapes that receive less than 6 hours of continuous, uninterrupted sunlight per day falls into the realm of shade. There is often confusion about the term "shade" applied to our gardens. It is often used as if it were a single condition but as gardeners, we all know that there are variations of shade too.

For convenience, I tend to divide shade into three categories based on the amount of light that reaches the plants beneath each day.

1. Light Shade - Also called dappled shade or partial shade, this shade is produced by trees with a thin canopy of small leaves. A clump of small birch, honey locust or dogwood trees would cast a dappled shade. It might be an area that gets 5 hours of sunlight split into two hours in the morning, two in the afternoon and one in the evening. Many plants will thrive in this amount of sunlight including some of the "sun-loving" types.
    

2. Moderate Shade - This is also known as medium shade or high shade and could be provided by large, old oak trees for example. The first branches may be thirty feet off the ground and plenty of light makes its way through. However, a direct shaft of intense sunlight rarely shines on a particular space for more than an hour or so during the course of the day. Many people feel that this may be the best type for most shady gardens. You could sit under this shade and read a book without any problem but the actual sun rays would only directly hit the book pages for short periods during the day. It is bright but little, if any intensive sunlight hits the plants.
    

3. Dense Shade - This is the deep, dark shade we find close to the north side of a building or under spruce or pine trees or Norway maples. As the sun goes across the horizon during the day, these areas receive no direct sunlight. The only light is that which is reflected from the surroundings. Immediately next to the north side of a building which has an overhang or under densely foliated trees such as Norway maples or spruce trees would qualify for this category.

Remember that all plants need a certain minimum amount of light intensity for them to complete photosynthesis. Some plants can carry on this process in extremely low light but most require at least what we call "bright indirect" light to function properly.

Hosta and impatiens are two species of plants commonly grown in the shade. Both are often called "shade loving" when, in fact, they are shade tolerant. Both will survive in dense shade but may not thrive and grow their best in those conditions. Planted under a spruce, both plants will generally grow very slowly. Given a bit more light, they will thrive. Both can be grown in the full sun but they will suffer unless soil and watering conditions are perfect. So, for most of us, they do best when grown in dappled to open shade.

Light and Moderate shade are ideal places in which to grow hostas and their associated companion plants. Under these conditions (given a water retentive soil enriched with compost), hostas will multiply as fast as the particular cultivar can and will flower at their best.

Dense shade is the most difficult environment for growing plants including hostas. Shade tolerant "woodland-type" plants will survive here but will probably not thrive. They may expand very, very slowly compared to the other shade types. Flowering may be poor or non-existent for some cultivars.