The Biscayne Times

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Aug 21st
Warmer Winters, Early Blooms PDF Print E-mail
Written by Jeff Shimonski, BT Contributor   
April 2018

Climate change evidence is in the leaves

IPix_YourGarden_4-18t looks like another winter has passed with little cold damage to our plants. As evidence, the photo that accompanies this article -- it shows a blooming Cattleya orchid whose flowers are a bit small and with a couple of stunted petioles. But with a very brief morning temperature of 49 degrees, the flowers came out anyway.

This orchid is happily growing on the trunk of a palm about six feet high and is exposed to windy conditions. My orchids never used to bloom before April or May because of the colder temperatures and the longer duration of those colder temperatures. But these past few years, everything seems to be blooming months earlier.

The same cold issues would occur with the blooming of bromeliads. At Parrot Jungle we’d always plan to have bromeliads begin to bloom around Easter, when colder temperatures would start to subside.

I did get a bit of cold damage this month on some of my more tropical plants. My small potted cacao, or cocoa tree, better known as Theobroma cacao, completely defoliated. I should have brought it inside on those nights when the temperatures dropped into the low 50s. I’ve eaten the fruit raw in the tropics, and it is delicious; but we’ll need much warmer winters before mine successfully sets fruit here.

My cashew nut, Anacardium occidentale, is also growing in a container, and while it didn’t drop its leaves, they did burn. A few days later, while inspecting trees at an older homesite, I noticed a good-size cashew nut tree growing in the backyard. This tree had no cold damage, and the canopy was full of healthy foliage.

The obvious thing difference, besides the cold temperatures, of course, is that I left the potted plants exposed on my porch, instead of heeling them into warm mulch or taking them inside. Years ago at Parrot Jungle, this was obligatory practice. The roots of potted plants suffered greater exposure to cold temperature than if they’d been planted in the ground. Imagine all that exposed plastic surface wicking away any heat within the pot.

Now with orchids, ferns, the occasional cactus (yes, some of them grow on trees), and bromeliads growing as epiphytes on the trunks and branches of trees or on the trunks of palms, I always made sure to soak the trunk, any exposed roots, and the plant itself with water about midday, when temperatures are at their warmest, before a cold night.

It’s important to soak the bark near the epiphyte, as the bark will absorb the moisture and this aids in retaining heat that may make the difference between a severely cold-damaged plant or a plant with just superficial cold damage. Even without pending cold, soaking or watering the bark is important for creating a moist environment for the plant’s roots.

I used to see lots of leaf drop on many tree species with cold spells. The next day after a strong cold front, our various ficus species would drop most, if not all, their green leaves. I haven’t seen that happen in a while, and certainly not this year.

Don’t mistake this green-leaf drop caused by cold with a normal leaf drop that occurs when many tree species replace their leaves. Our sausage trees at Parrot Jungle used to drop all their leaves with a strong cold front in December and wouldn’t begin growing new leaves until spring. The blooms always came out first, before the new leaves.

Trees blooming in winter, without a canopy of foliage, is normal. Our winter corresponds with their natural dry season. The leaves drop, the flowers emerge and get pollinated, the fruit forms, and then new leaves appear.

This makes sense from a natural history point of view. The foliage would only obstruct the view of flowers and would make access to them by animal (bats or birds) or insect pollinators difficult. Foliage and flowers together mean less fruit set -- not a good thing for the tree trying to propagate itself.

With our warmer winters, you can now see frangipani trees, royal poinciana, and other species with full sets of leaves with flowers. The leaves are dropping incrementally while new leaves are emerging. This occurs especially if the winter is particularly rainy or if the irrigation system is running on overtime in the yard or adjacent yard.

There’s no normal dry season anymore. I’m seeing lots of sausage trees with both foliage and flowers in winter. It used to be so easy hand-pollinating sausage tree flowers without a canopy of foliage to get in the way of the ladder or cherry picker bucket. Imagine how difficult it is for bat pollinators to access the flowers now.

 

Jeff Shimonski is an ISA-certified arborist, municipal specialist, retired director of horticulture at Parrot Jungle and Jungle Island, and principal of Tropical Designs of Florida. Contact him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

 

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