Van Dycks

For some time I assumed it would take a botanist to be able to figure out whether a particular plant would be happiest in sun or in shade. I figured they probably hooked each plant up to some sophisticated machine that would show them something we mere laypeople couldn't possibly comprehend - and from there tell us where the plant would be happiest.

Of course, later I realized that it was usually much more simple than that. Every plant is native to some place, where it can be found naturally growing under whatever conditions it most prefers. All you really had to do was pay attention to that. So if you know that hostas are generally found in Japan, in shady areas, and usually near running water, you can assume safely that hostas like a temperate climate like that of Japan and most soil.

Of course, A little experimentation and a lot of mistakes by unknowing gardeners soon showed up that hostas would grow in dry soil as well as damp. People either knowingly or otherwise planted them in drier areas and found that they survived quite well. Still others planted them in sunny areas and found that some did quite well there - where others simply shriveled or bleached or burnt. So they started paying attention to the differences among those that grew in sun and those that didn't and found that those with gold colored leaves could take sun - and those with blue turned plain green - and most of the rest really seemed to prefer at least part shade to do their best.

OK - so knowing where a plant grows naturally may not tell us the whole story. But it's a clue.

But what if you don't know that? Have you any idea, for instance, where hyacinths grow wild? Or fritillaria?

And if you don't - how else can you tell?

If you're lucky, you will have a tag or something attached to the plant when you receive it that will just tell you. But tags have a way of getting separated from the plants to which they belong - and then you need to rely on other clues.

Such as leaf size. Leaves that are tiny are great for sunny areas because they don't lose a lot of moisture to evaporation. Large leaves, with their huge surfaces areas, can lose a lot of moisture on hot sunny days, and so will never be as happy in full sun as their small-leafed counterparts.

For the most par,t the leaves of plants for shade are thinner than full sun plants, simply because they won't need the thickness to hold in that moisture that the sun deprives them of. If you find a very thick-leafed plant - like a cactus, jade plant or other succulent type, you know it's a sun plant - the leaves actually carry a supply of water for the plant.

Of course, there are always exceptions. Many hostas have very thick leaves - partly to make it harder for slugs to eat them (slugs are too lazy to attack anything that takes a lot of chewing). Also, the blue hostas feel thick because they have a sort of waxy coating - which is what makes them appear silvery blue. But sunlight will melt that wax coat right off - and the hosta will not only look plain green, but will start to scald.

Color can also be a clue - albeit a confusing one. Gold hostas, for instance, are the one color that will take full sun. But gold is one of the more common foliage colors for shade plants - a mechanism that allows them to be seen in dim light conditions. That gold color is there to attract bees and pollinating insects that otherwise might not notice them.

Most shade plants will have pale colored flowers - or, in some cases, extremely bright ones. The same principle applies - they are colors that will attract pollinators. Sometimes a plant that normally prefers sun will have a flower in a deep bright color - and you may notice that the color fades or spots in that sun. Daylilies are famous for that - most love full sun, but the bright reds and purples will bleach out and actually prefer a bit of shade.

If you see a plant that is silvery colored, you can almost guarantee that it is a full sun plant. If you look closely, most silver plants are actually green, but finely covered with tiny hairs. The hairs are what make the plant look silvery - and the hairs are there to help the plant retain moisture while growing in strong sunlight.

By the same token, many of the dark leafed plants that are so popular now are actually shade plants. In their case, it is more like camouflage, to protect them from being picked in the wild to the point of extinction. Oddly, though, these shade plants don't produce their best, deep dark colors unless they are grown in sun. But they won't be happy there unless they get plenty of water. Sunlight causes plants to leave moisture through their leaves - so it stands to reason that if you make up for that moisture loss the plant will be happier than it might otherwise be.

Or look at Colocasia 'Black Magic'. It looks coal black in sunlight. But is also considered to be a bog plant - one that grows happily in very moist soil.

Have you noticed, during the droughts that have plagues so much of the country over the past few years that shade gardens survived better than those in sun? That's one of the main reasons. Their moisture content didn't evaporate as fast as the plants in sunny areas.

Another characteristic of shade plants is that most of them tend to be shallow rooted. That means that even with a minimum of rain, the roots get the moisture they need, whereas plants with deep roots may only receive a drink at the top, while the roots that go more deeply remain dry. Shade plants generally developed these shallow roots to allow them to survive under large trees which often have gigantic root systems that they have to compete with. They tend to be sensitive to moisture levels - but a home under a tree is a great natural place for them, as they get mulched naturally by leaf litter, which helps hold moisture into the soil.

By contrast, a taproot is actually the sign of a sun-loving plant. Taproots can go very deep - deep enough to go into the earth in search of moisture at lower levels. (If you're not familiar with a taproot - think if carrots. A carrot is actually a taproot. But some plants send down roots that get far longer than any carrot that I've ever seen. Usually the deep, deep taproots seem to belong to weeds. They are not only drought tolerant but impossible to dig out.

Bulbs, corms and tubers are also root systems. Some bulbs are fairly shallowly planted and others are quite large and need to be planted deeply. But with few exceptions, bulbs like to be in a dry area - except during their natural growing season. That is why they do so well under trees. They get moisture during the spring rains (April showers remember?) And they also get plenty of sun then, because the tree hasn't leafed out yet. After that they like it to be dry - and the tree roots tend to grab the moisture before the bulbs can - which is fine with them for the entire rest of the year.

Finally, have you ever noticed that most shade plants are relatively low growing? That's because they don't feel the compulsion to reach up for the light the way the sun lovers do. In the natural process of evolution, the sun loving plants developed the capacity to grow upward so they would get the sun - shading out their lowlier companions, who adapted to the lower light conditions.

What it all boils down to is that you can usually rely on a few clues about any one plant that will allow you to make a reasonable guess about where it will be happiest. Leaf thickness, depth of roots, height and color plus size of leaf are all clues - and when you see three or more clues that a plant probably likes shade, or prefers sun, you know that it is where the plant will be happiest.

Shade plants, however, can often adapt to sunny conditions if kept moist, whereas sun plants in shade tend to become stunted and unhappy. They need that sun for proper photosynthesis, and without that grow pale and wan and miserable.

When in doubt, if you can't find any information about your new plant, try for a situation where the plant will get about 5-6 hours of sun - a reasonable compromise. Remember that afternoon sun is hotter than morning sun - so if you think yours tends more toward being a sun lover plant it where it will get its 6 hours in afternoon.

And -as always - when a plant seems unhappy try moving it. Sometimes even a difference of a foot or two can make the difference between an unhappy or indifferent plant and a great one.