Here is a little lesson about how culture can affect plant growth. First, what do we mean by the word culture in horticulture?
Culture is the set of conditions the plant needs to thrive. Proper moisture, soil, sunlight, nutrients, etc, according to each plants’ needs.
Maintenance, on the other hand, is what we humans need to do to provide the proper culture requirements for the plant. Watering, weeding, fertilizing, pruning, etc.
Sun Exposure Can Affect Foliage Color
This plant in the photos at right is Oreganum vulgare ‘Aureum’—Golden Marjoram. Both photos are golden marjoram growing in my yard, but not the same actual plant. The upper photo is golden marjoram planted in an area that gets roughly 6-7 hours of sunshine daily, starting in the morning. The lower photo is also golden marjoram, but it’s planted in a location that gets only 2-3 hours of sunshine daily.
‘Aureum‘ is a Latin word that means gold. But these photos clearly illustrate how a plant’s coloration can change depending on how much sun it receives. Golden marjoram is only truly golden in full sun conditions. Like the golden plant, the greener plant flowered, is evergreen, and grew in roughly the same habit (though it was a bit leggier)—it’s just not very golden.
Other Plants Affected by Sun and/or Season
In general, plants will only attain the size, color and other of it’s normal attributes when growing in it’s preferred conditions. If the tag says the plant will have golden foliage and it prefers full sun, then there is a good chance if you plant it in shade, it will be green rather than golden. In fact, it may not tolerate shade at all, or vice versa. Some yellow-foliage plants are yellower in sunshine, others are yellower in shade.
Some green-foliage plants—like Skimmia japonica—are nicely green in shade, but get bleached to yellow or almost white when in full sun. Other green-foliage plants—like Leucothoe fontanesiana ‘Scarletta’ (Fetterbush) and Nandina domestica (Heavenly Bamboo)—are green in shade, but turn red, burgundy, russet, orange, or bronze with more sunshine in winter. Some azaleas, heaths and heathers do this as well.
Some burgundy-foliage plants—like Berberis thunbergii atropurpurea (Japanese Red Barberry)—prefer full-sun exposure and lose most all of their burgundy color in shade, becoming almost completely green.
Some plants’ leaves—Nandina domestica(Heavenly Bamboo)— or branches—Cornus sericea (Red-twig dogwood)— color up nicely in wintertime in full sun, but they barely color at all in shade.
Many hostas look quite different depending on if they are in full or only partial shade. Many variegated foliage plants lose most of their variegation given a sun exposure that is not of their preference.
So when you are looking for plants with other-than-green foliage (or bark, etc), take care to read the label and do a Google search for more information regarding how the plant will behave if it doesn’t receive it’s preferred sun exposure.
Size and/or Shape
A plant’s size and/or shape may change—often radically according to it’s being grown in sun or shade. Two notable plants in our area (Pacific Northwest) are: Vaccinium ovatum (Evergreen Huckleberry) and Acer circinatum (Vine maple). Both of these plants grow compact and in a very dense, shrub-like form in full sun. And they both will be at least twice as tall, leggy, and vine- or fern-like in full shade. Vine maple gets it’s name from how it stretches it’s branches out reaching for sunlight in the understory of our Douglas fir and big leaf maple forests. Evergreen huckleberry looks more like a very tall (often 10-12′), lacy fern than a shrub in full shade.
And please note that plants generally prefer certain growing conditions. If the plant’s label says it’s ‘drought-tolerant’ or ‘shade-tolerant’, it means that it will tolerate those conditions, but it won’t necessarily enjoy growing in them. Liking and tolerating are usually very different things. Many humans tolerate short periods of being too hot (or too cold), but they don’t at all enjoy being hot (or cold). We can tolerate skipping a meal, but we don’t enjoy it.
Same with plants. Many can tolerate periods of drought, but they would prefer getting regular water (or sunshine, or mulch, or fertilization, etc). Many can tolerate shade, but prefer full sun. Unless the label (information) specifically says something to the effect, does equally well in sun or shade, assume it will not look exactly the same in both exposure conditions.
Here ends today’s horticulture lesson.