Thursday, December 18, 2008

Okay, So I'm a Bit Obsessed

But it isn't my fault really. Charleston is just such a great laboratory for observing microclimates. Like this tropical hibiscus blooming today in downtown Charleston long after the hibiscus in my yard just across the harbor were killed by the frost. This particular plant bloomed all last winter and never had any frost damage at all and is now reaching for the second floor of the building.
This plant, though, was born with a horticultural silver spoon in its, ah, mouth:
  • It is planted up against a heat-retaining brick wall.
  • It is located just a few hundred feet from the Charleston Harbor where the heat retained by the water warms the air a bit. The entire penninsula of Charleston is warmer than surrounding areas because the two rivers that flank it provide a slight warming to the air.
  • It is located in downtown Charleston which is warmer due to the effects of the urban heat island.
I'm very jealous. The hibiscus in my yard won't bloom until next fall because they will have to come back all the way from the root IF they come back at all. What a difference a few miles can make.

Thursday, December 11, 2008

Broms of December

The surprise of tropical color on a gray winters day should be enough to convince anyone in the coastal South to grow bromeliads. I've watched many a woman stop in her tracks and ask me what that beautiful flower is and may she have a piece. Aechmea gamosepala has that effect on people. The blue flowers on a pinkish-purple spathe screams "hello" while the thornless leaves are gardener friendly.

The above picture shows the plant crawling up a live oak trunk providing both the shade and shelter from frost that this plant needs. White frost will damage this plant but I've seen it undamaged by 22f under an evergreen canopy. Just place it at the base of a tree and this plant will make itself at home with a minimum of care. As a small ground cover it is so dense few weeds can penetrate.

Another great one is Aechmea distichantha (above), with its bright pink spathes that remain brilliant for months after the flowers fade. The plant is wickedly thorny and depending on the variety can be huge, with leaves over two feet long tipped with a spine that can penetrate leather.

Easy to grow whether in a crotch of a tree or as a specimen on the ground all the plant requires is part shade and a well drained site as do all broms . Under the canopy of a tree the plant has taken temps down into the upper teens undamaged. There are three different forms on the market that vary in size from 1' tall to a variety that has curved leaves that are 3' long. The bloom season varies but it is always at the darkest time of year.

Saturday, December 6, 2008

The Tropics Are Just a Live Oak Away

The tropics are just a live oak away? Okay, maybe not. There are no coconut palm lined beaches magically appearing on the other side of my live oak tree. There is no secret door in the trunk that magically opens to a warmer, sunnier place. But.....there are tropical plants that thrive under the live oak.

Charleston straddles USDA Plant Hardiness Zone Ho-Hum (or 8b), with minimum temperatures of 15-20 degrees, and USDA Plant Hardiness Zone Ooh-La-La (or 9a), with minimum temperatures of 20-25 degrees. What grows in Zone Ooh-La-La? Think tropical hibiscus, some bromeliads, an expanded range of palms, tropical ferns. I want that! So I keep shoving more marginal plants under the protective canopy of my live oak.

The happy little collection of strobilanthes, aechmea, vriesea gigantea "Nova", and monstera in this November 30 photo was unscathed by the scattering of freezing temps that had knocked back other tender plants in exposed areas of my yard. Will they all make it through the winter? Who knows. I have serious doubt about the monstera and even the sturdier plants in that group may die if we have an exceptionally cold weather. In the meantime though, I love having that bit of color hanging on in my yard.

A live oak can help gain those few precious degrees that mean a tropical that would normally die is instead root-hardy (hopefully the case with the monstera) or that a tropical that normally would only be root-hardy is evergreen (for example, the Persian Shield). On a cold night, the closed canopy of the live oak acts like a cozy down blanket by trapping the warmer air radiated up from the ground. That same "blanket" also prevents plant cell damaging frost from settling on leaves and stems.

How much of a difference does it make? Seeing is believing. In a downtown Charleston park, this Persian Shield, lying just a few feet outside the dripline of a Live Oak, was top-killed by freezing temps a few days ago:
But just ten feet away, under the protective cover of the same Live Oak, this Persian Shield is untouched by the cold:

And because it hasn't been killed back in years, it has these great big leaves:

Same story with this groundcover which is also outside the dripline of the Live Oak:

And again just ten feet away, is the same plant, same day:

I have no idea what this little groundcover is. Any suggestions? I do know that under that tree it is perennial.
Of course, it isn't only live oaks that afford some freeze protection. This Blue Daze is sheltered by the lorapetalum in the background but just a few feet away ten more Blue Daze are all top-dead:

If these plants all thrive this winter, my azaleas and holly ferns had better watch out... Zone Ooh-La-La will be moving on in!

Friday, December 5, 2008

Christmas Cheer Charleston Style

Poinsettia in Charleston

While we winter weather wimpy Charlestonians were turning our thermostats up and complaining about a few hours of freezing temperatures, this garden poinsettia maintained its focus and was thus able to pull off a few blooms just in time for the holiday season. Now as anyone knows who has ever mistreated their brand-new florist poinsettia, they don't like the cold, much less a freeze. But this poinsettia was protected from the freeze by the top-secret frost protection gizmo of....

Deep eaves

very, very deep eaves that kept white frost from settling on the leaves. Lots of tropical plants in Charleston that were unlucky enough to not have such protection were knocked back by freezing temps a couple of weeks before this picture was taken. The old Navy base where we found this plant has been closed for years so it is pretty safe to say this plant has been neglected.

We both remember when there were several poinsettias in the ground in downtown Charleston which for the most part, modern landscaping has eliminated (the plants, that is...not Charleston). And that is quite a shame as poinsettias are part of Charleston history. Their discover, Joel Poinsett, was born right here. He served in a number of political roles including being our first minister to Mexico (that was an early form of ambassador and yeah, I had to go googling for that detail) which is what he was doing when he found this member of euphorbia family growing in southern Mexico.

I think the moral of this story is to experiment with planting some marginally hardy plants under hard shade in the form of an overhang, an evergreen tree like a live oak, or even an evergreen shrub. I'm obsessed with the topic of frost protection right now so stay-tuned...more to follow.

Wednesday, December 3, 2008

Camellia sinensis at CawCaw

It looks like a bit of spring but instead it was a crisp, fall day when this image of a tea plant (camellia sinensis) was taken at CawCaw Interpretive Center, a Charleston County park. Early in the twentieth century there were scattered attempts to grow tea commercially just south of Charleston. Today, at this former site the land has returned to forest but the tea has survived and naturalized.

The park is a beautiful slice of the Carolina low country with abandoned rice fields that are now fresh water marshes filled with alligators and birds or swamps now dark with trees and dwarf palmettos.

The tea grows on the higher, drier areas, sometimes just a single plant but other times as a hedge running through the woods. Flowering occurs in October and November on plants that are 4 to 5 feet tall. The forest above them is composed of oaks and spruce pines and allows a moderate amount of light to penetrate.

Caw Caw is a beautiful park developed as a nature reserve for walking among the diverse habitats that can occur in a small area. It is easily accessible and a true joy to walk.