November 12, 2010

Whatever Happened to All the Poinsettias in Florida Gardens ?

Poinsettia hedge

A modern poinsettia inflorescence

a montage of poinsettia varieties

an "old style" poinsettia hedge with narow bracts
 These Mexican natives thrived in our climate of hot,rainy summers, and cool, dry winters. I remember seeing pictures of people proudly showing off their Poinsettias, usually on the south side of their homes, ablaze with color in winter. For many homeowners, they were just ordinary landscape plants with sticky sap, needing pruning every late Summer and little care after that. Gardeners would propagate them easily by cuttings in the spring, and the plants grew to magnificent dimensions. In dry winters I saw thousands of homes with great splashes of red in the landscape.

I noticed that a lot of people looked at my blog about what happened to Hibiscus in Florida. The comments about the disappearance of old Hibiscus reminded me of the nearly total loss of Poinsettias. I've been asking University of Florida Extension agents  for a long time about the mass disappearance of these gaudy yet iconic plants. The answers seem simpler than I would expect:
  1. insects and nematodes have decimated the plant 
  2. the stalwart varieties that used to be grown as garden plants are highly susceptible to modern insects and nematodes. 
  3. modern insects chew up the stalwart poinsettia varieties, and the insects are highly resistant to "conventional" insecticides. 
  4. new poinsettia varieties don't grow as landscape plants as well as the old ones do.
This is a classic case of how the "old varieties" are unable to keep up with modern diseases and pests. Or, said in a different way, the pesticide-resistant pests have wiped out plants that have been here for decades, if not centuries. There are new insect pests in Florida of Gumbo Limbo Trees, Crotons, Ficus, Coconuts and a wide range of other stalwart varieties of landscape plants. The big question would be how to arrest this trend of new pests annihilating old plants. The only long term solution is to breed and select plants resistant to the pests and diseases. The Catch-22 is that by the time the breeders get around to producing new plants, we have a new range of pests and diseases introduced to overcome.

If you wish to grow some of the old style of Poinsettias, use a very well drained organic soil, in a location with all-day sunlight. The organic soil will help retard nematodes ( omnipresent microscopic parasitic worms in the soil) which thrive in dry sandy soil. Plant new plants in May or June, and fertilize monthly with palm fertilizer. Tend to pest problems with organic pesticides like soap/ oil sprays to control whiteflies and mealybugs. Prune the plant heavily every 2 months to induce a lot of branching, then stop pruning by Labor Day. Reduce irrigation after Labor Day to the point where you water the plant only when it wilts. Poinsettias and Bougainvilleas can be tended to on the same schedule, and can grow side by side.

Give your Poinsettia plenty of room, some gentle neglect, attention to pests, and diligent pruning, and it will reward you with a brilliant show of color for months. Perhaps we can start a renaissance of Poinsettias, with a modern twist.

Craig Morell
Pinecrest Gardens               

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