THE COASTAL GARDENER:Summer heat is perfect for tropical plants to thrive

The long, hot days of summer are taking their toll. Many of the plants that were so glorious just a couple of months ago are now stressed in the heat of August. Roses have only an occasional short-lived flower. Lavenders are stringy. Groundcovers are parched. Gardens and gardeners both are strained at this time of year.

But one group of plants is thriving: tropicals.

The hotter the better for plants originating in the hot, steamy jungles of Africa, South America or Asia.

These plants, from the world’s equatorial regions, evolved in a climate of high day and night temperatures, humidity and moisture.

While unhappy during the cool half of Orange County’s year, they thrive during our warm summer. Unlike most of the plants in your garden, now is the time for tropical plants.

Common examples of tropical plants in our coastal gardens are plumeria, elephant ear, canna, banana, ginger, staghorn fern, bromeliad, anthurium, scheflera, philodendron, mandevillea, most palms and jasmine.

Many other plants you may not suspect as tropical are bougainvillea, asparagus fern, avocado, impatiens and begonia, even Bermuda and St. Augustine grass.

Surprisingly, nighttime temperatures may play the most significant role in the fast summer growth routine of most tropical plants.

During our warm, balmy nights of July, August and September, our tropical plants are growing nearly nonstop — even in the middle of the night.

Plant cells divide and leaves expand around the clock as tropical plants store the afternoon’s solar energy, fuel for their busy photosynthetic factories.

In simplistic terms, plants are either tropical or temperate. Tropical plants populate the regions of the world near the equator.

In tropical regions there is little seasonality. Winter temperatures aren’t much different than summer temperatures. In contrast, temperate plants occupy areas farther from the equator and closer to the poles.

These plants are accustomed to a cool season and a warm season, to varying degrees, mostly depending upon their latitude.

Understanding the differences between tropical and temperate plants is often seen as a milestone in a gardener’s education.

Rosemary, birch, olive, hawthorn, daylily, pittosporum, boxwood and thousands of other plants in our gardens are temperate plants. These plants either slow down or stop growing completely during Orange County’s hot summer months. But temperate plants also include peaches, apricots, plums and other stone fruits, Japanese maples, phormium, azalea and camellia, and our native plants.

To the novice, it looks like these plants are growing; they’re green and they have lots of leaves. Looks can be deceiving.

They’re not growing, at least not much.

If you need proof, tie a string an inch from the end of a branch on a few of these plants in your garden. Check the string again in November. Not much change.

But while the masses of your garden, the temperate plants, are resting a bit, tropicals are not.

They have no time for rest, not now, not during their favorite time of the year — summer.

However, to grow well, tropical plants do need one thing , in Orange County at least, only a gardener can provide. Summer water and lots of it.

To accompany their love of warm temperatures, tropical plants have grown dependent upon water. Surprisingly shallow roots, leaves that transpire water quickly and almost no water storage ability leave them dependent upon a ready supply of water. Provide your banana, elephant ear, canna, philodendron, mandevillea or palm with plenty of water and they will grow big, lush and strong.

While gardeners wilt under the heat of summer, tropical plants couldn’t be happier.

ASK RON

Question: When is the best time to prune a camellia?

Karen

Answer: Camellias do not require much pruning. But if you do need to shape the plant a bit or head back its growth, you’ll need to do it right away. Flower buds begin developing in the next month or so. Any pruning after this will destroy next year’s flowers.

The very best time to prune a camellia is immediately after the last flower has faded. For most Japanese camellias this will be sometime between February and May.