Hello All,

I hope everyone had a wonderful summer. School started last week and people are just getting use to their new schedule. The normally sedate summer Miami traffic has degenerated back to the maniacal form of movement where a red light means speed-up so you can pass through cross street traffic like fast thrown pencil moves through the spokes of a spinning bicycle wheel. Anyway, I hope you are readjusting to the fall schedule. Since it is going to start cooling off, I thought we might look at how we protect plants from the cold. Of course, this is Miami so by cold we mean temperatures below 40 °F (that is about the temperature inside your refrigerator).

For plants that don’t have enough sense to come in out of the cold, we can send them to their room. This is the banana room (picture below). Tropical plants, ones who like it hot all year round, will start to get cold 

damage when temperature’s drop into the low forties (40 °F). That is because tropical plant enzymes (proteins that will grab a specific compound and hold it still, then grab a different specific compound and hold it still so that the two different compounds can combine to form something a plant really needs),    . . . tropical plant enzymes don’t like cold. For example if a plant needs to make starch, it has to take two smaller sugar molecules called glucose and bond them together. The enzymes (it takes more than one) are shaped so that they can only grab a glucose molecule. If it gets too cold the enzymes loose their shape and can’t grab glucose, so no starch is made. In Florida, temperature’s can get into the low forties during winter nights. To keep it nice and warm for bananas, we grow them in these open-air rooms. In the day, the sun heats up the walls. At night, the walls release that heat and banana can stay warm. This method works if the temperature does not get too far below 40 and only lasts for a few days.

Another trick for plants that can’t come in from the cold, is to spray water on them. When water turns to ice it releases heat known as the latent heat of fusion. As the air temperature drops to around 34 °F, you spray a fine mist of water above plants. If the temperature drops to freezing (32 °F) water turns to ice and releases enough heat to keep the temperature near the plants from dropping any lower. This trick works at temperatures a few degrees on either side of the freezing. By-the-way, freezing does not necessarily kill the plant. Freezing damage usually occurs because plant cells thaw unevenly, cracking cells open and allowing all the good stuff inside to leaks out.

Some outdoor plants can be moved indoors when the weather gets cold. We put them in our greenhouse or in a room that gets the right amount of sunlight. Plants that grow in the open are put on a windowsill that gets a lot of light; plants that grow in the shade are put on a counter that does not get direct sunlight. A greenhouse usually has clear glass walls and ceiling. Light comes through the glass and heats up the greenhouse. Whereas, the light can penetrate the glass, heat cannot. Once sunlight heats a greenhouse the glass walls trap heat inside and keep it warm despite cold temperatures outside.

This is our cacao greenhouse. Cacao is a mid-story forest plant (larger trees grow around it blocking some of the sunlight). Because cacao likes partial shade we painted the glass panes white so the right amount of sunlight enters.

When it gets a little too chilly we give plants a blankie.

Or when they go outside we wrap them in a nice warm sweater.

When it gets too cold in the greenhouse, we turn on a heater.

The grass in trays at the bottom is sugarcane.

The fan helps circulate the warm air.

Small plants get a little jacket. It is clear, like the greenhouse walls, to trap heat. This plant only needs protection for the sensitive aboveground growing parts.

These plants need protection down to the pot surface. During a south Florida winter the ground tends to stay warmer than the night air. Plants that have a growing point below the surface can have their top parts dieback. Underground parts survive freezing temperatures in the warmer soil. In spring they can regrow.

Some of our Madagascar palms like this stylist red-striped cover.

Some go with a conservative white stripe.



But regardless of what color of protection they like, tropically evolved creatures like avocado, cacao, and people need to keep warm when temperature gets near freezing.

Newsletter #5 "The Pit"

Hello family, friend etc.

I know it has been a long time but i have been very busy here. Last time I promised to take you down into a pit but first let’s talk about how some of these pits form. As a surface feature Florida is very young, just a baby landform. It was born roughly 10,000 years ago. The bedrock below Florida was formed under water by all sort of ancient marine or sea creatures like clams (fossil clam shells are everywhere). They would die and settle on the sea floor. Here they would become cemented together to form rocks. This happened over millions and millions of years so there are very thick deposits of these rocks. Ten thousand years ago sea level reached current levels and the rocks were exposed at the surface. Because Florida is so young, only a few inches of ‘dirt’ (wind blown sediments) have been deposited over these rocks. The rocks have a lot of calcium carbonate in them (baking soda is similar to calcium carbonate), which as rocks go will easily dissolve in water. It rains a lot in Florida! After a couple of thousand years of teeny-tiny bits of rock slowly dissolving and being wash out to sea, the remaining rock has lots of small holes and tunnels in them. Eventually the rock will not be strong enough to support itself and collapse to form a pit called a sinkhole.

I like that story, it is true but two things I should admit: 1) the pit we are going to visit is man-made. In the 1920’s they dug out the rocks to build some of the older buildings here. We have not planted anything interesting in the natural pits (just tree after tree after tree of avocado). So I’ll show you a man-made pit.  2) Rocks and soil particles slowly dissolving and getting washed out to sea is why the sea is salty!

People like to plant Fruit trees in these pits; the soil is better and the trees are protected from the wind. Usually we get more and bigger fruit from trees planted in sink holes than from trees planted above on the flats.

The first picture shows bedrock at the surface, just above a man-made pit. Picture two shows the pit wall with thousands of small holes created by water dissolving calcium carbonate in the rock. Picture three is fossilized sea creature (I tell people it is a sponge but I really don’t have a clue what it is). This rock was too cool to be used as a brick in a building so they put a bunch of these around a small garden in front of my old office.



Bedrock on surface



bedrock along pit wall



 

Fossilized sea creature



This is the edge of our lychee and jackfruit pit. It is about ten to fifteen feet to the bottom.



Jackfruit Pit



 The first tree we will visit is Artocarpus heterophyllus or the jackfruit (picture below). The benefits of jackfruit were promoted Ashoka the Great of India (274 – 237 B.C.), the world’s most famous vegetarian. And why not promote jackfruit if you’re going to be called the Great? Jackfruit is the world’s largest fruit. The fruit can weigh up to 80 pounds and be 3 feet long. It is the main flavor component in juicy fruit chewing gum. Before old Ashoka the Great began telling people about how good jackfruit was, the king was called Ashoka the fairly mediocre.

(Artocarpus heterophyllus) Jackfruit

The actual fruit is so large it grows directly on the trunk or branches big enough to support it.

 

And what story about south Florida would be complete without a palm tree?



Cocos nucifera (Red Spicata palm)



According to the National Tropical Botanical Garden’s website

“The trunk is very strong and elastic, and is able to bend in heavy winds. In times of hurricanes the coconut palm has been a lifesaver. People lashing themselves to this flexible tree have avoided being swept out to sea. This palm is the most useful plant of the tropics. It is said that more uses are made of it than any other tree in the world. Besides drink, food and shade, it offers the possibilities of housing, thatching, hats, baskets, furniture, mats, cordage, clothing, charcoal, brooms, fans, ornaments, musical instruments, shampoo, containers, implements and oil for fuel, light, ointments, soap and more.“

You can read more about this palm at their website:

http://www.ntbg.org/plants/plant_details.php?plantid=11820

The last tree we will visit in our pit is the lychee (Litchi chinensis) from southern China. Fruit from this tree become ripe for only a short time in late spring. Under its leathery skin there is a clear (grape-like) sweet pulp. It is verrrrry tasty but only available for a short time (around June in Florida). As a result, in first century China the Emperor developed a version of the pony express to deliver fresh lychee to his wife. This variety is called Brewster, named after the Reverend W. N. Brewster a Methodist missionary who introduced it into the U.S. in 1903. In China they call it Chen Family Purple.

Lychee (Litchi chinensis)

Lychee fruit

Peal off the red skin and suck the clear pulp from around the large black seed.

Since it has been a very cold and snowy winter up north, next time we will look at how we protect tropical plants when it gets so bitterly cold the temperature drops below 40 degrees.

Goodby for now.

stewart