The effects of the 10-day blast of cold air are showing up throughout South Florida, including our tropical garden. Yellow and brown leaves are revealing how sensitive tropical plants can be to to four days of below 40-degree temperatures, especially after very warm days in November and December.
|Fairchild explorers took a close
look at cold damage in the
The rainforest understory was hard hit, with heliconias, gingers and many plants in the aroid family, such as small philodendrons, showing their dislike of chilling wind and cold. It has been many years since the thermometer plunged that low for such an extended period.
More than 500 plants are showing some damage. Marilyn Griffiths, the garden's plant recorder, is documenting the damage, and the data will be used to follow these plants in the future. Heliconias are being cut and they will sprout back in the spring. Many palms are showing damage to their lower fronds, with some palms gradually dropping them. Senior horticulturist Mary Collins said some palms will not show damage until warm weather returns and they push out new spears that could display some distortion.
Leaves on shrubs and tropical trees that have been scorched brown are being left alone in case there is another cold snap. They can protect other leaves. Pruning now will encourage new leaves to sprout. New, tender growth is always the most susceptible to cold damage.
At the Fairchild Farm, Richard Campbell reports that the avocados and mangos did just fine, but the jackfruit and mamey sapotes were badly damaged. The ground actually got colder than the air, he said, and so the trees were hurt through the roots and from the ground up.
But fear not, most of the garden’s plants will come back as the weather warms up. In the meantime, our staff horticulturists are carefully monitoring plants for signs of fungus or bacterial disease.
|Scorched leaves hanging
from twigs may mean
twig or branch dieback.
Jeff Searle, a nurseryman known for his exotic palms, has been growing crotons rather feverishly over the last five years, and he gave a whole course in growing them for the Tropical Fern and Exotic Plant Society this week.
Cold damage was the hot topic, of course. And he said leaves falling off are a better sign than leaves dying and hanging onto their twigs. Scorched and clinging leaves are not a guarantee that plants will die, but it doesn’t look good if that’s what’s happening. Cut back on watering and keep crotons on the dry side for now, he said.
Generally, crotons like semi-shade and not full sun, Searle told the society. They do best in acid soils. He uses the palm special fertilizer twice a year and sprays his plants with liquid azalea fertilizer once a month. (Azaleas also love acid.)
Yellow and green crotons usually grow larger and faster than the red-leafed varieties. They’ll also do better in full sun. Crotons with pastel leaves do well in shade. (Most crotons thrive in full morning sun or afternoon sun, but not midday sun, especially in summer.)
|Mrs. Iceton is a pastel
croton that does best in
There are about nine different leaf shapes, Searle said, and they range from huge broad leaves
|Irene Kingsley is a croton with
oak leaf-shaped leaves.
(General Paget) to recurved leaves (Ramshorn). In between are oak leaf (Irene Kingsley) and semi-oak leaf (Sybil Griffin), spiral leaf (Dreadlocks), narrow leaf (Stoplight), very narrow leaf (Majesticum), small leaf (Aureo Maculatum) and interrupted leaf (Interruptum), which has a narrow piece of midrib between most of the leaf and a rounded leaf tip. Because crotons are so genetically unstable, different leaf shapes and colors may occur on the same shrub. New to crotons are Thai hybrids, which are wonderfully curly-cued, but very slow-growing.
Croton scale is a new and aggressive problem for the plants. A natural enemy called the mealy bug destroyer does feed on it, but the scale may out-run the enemy. Horticultural oil is recommended for the crawler stage but requires several sprays; Bayer’s Advanced Tree and Shrub insect control can be used as a systemic drench.
Cold damage creeps on little cat feet, it appears. More yellow-then-brown leaves seem to reveal
|This bird's nest Anthurium was
not covered for the cold.
themselves daily. Back in 1980, the International Aroid Society’s journal, Aroideana, published a small field study by Mark Moffler of the degrees of cold damage on aroids he was growing in Tampa. “The self-heading or arborescent philodendrons (Philodendron selloum and P. x evansii) and the birds-nest anthuriums (Anthurium hookeri and A. schlectendalii) appear to be the hardiest,’’ he wrote, while dieffenbachias and aglaonemas suffer in cold and need protection.
|This aquatic aroid sat in warm water but was killed anyway.|
Although colocasias, caladiums, alocasias and xanthosomas may be damaged and “go down in winter,’’ he continued, “they come back in the spring and can provide an excellent landscape accent.”
A lot depends on exposure and overhead canopy, wind protection and other factors. I’ve seen some totally brown monsteras and others that are unscathed. A tiny Anthurium clarinervium, one of those lovely velvet-leafed species, was killed in my shadehouse, while a mature A. magnificum is fine.
Chris Migliaccio, who will teach a Tuesday, Feb. 16 class called “Aroids from A to Z” from 7 to 9 p.m. at the garden, said “Generally heavy leaves are more hardy.” He plans to water less now, about once a week, and fertilize in March.
Deadline for online registration for Chris’ class is Feb. 12, and he will have a much better idea of survival rates then.
|Paris Parise holds a chocolate
cupcake and nibbles on a
A true gift of the rainforest, chocolate has tickled taste buds for hundreds of years. In celebration of this rainforest treasure, all things chocolate were delighting youngsters and oldsters at the garden Friday at the start of the 4th International Chocolate Festival. A teacher’s workday freed lots of eager young chocolate tasters, but children weren’t the only ones to pursue the seductive flavors. A bus of folks came over from Naples, and women in red hats were well represented at lunchtime.
The garden house is full of chocolate makers and chocolate
|Jennifer Hernandez beholds
M&M-covered candy apple.
sellers. Rocky Mountain Chocolate Factory, which really resides in The Falls shopping mall, brought chocolate and caramel covered apples decorated with sprinkles, M&Ms, white chocolate and more. Wendy’s Chocolates had lots of kid-sized cupcakes, and New York chocolatier Oliver Kita brought handmade chocolate Buddhas, Valentine’s boxes filled with such exotic flavors and passion fruit and lychee bonbons, and even chocolate dipped whole caramelized almonds on white chocolate disks. Forget the New Year’s resolutions.
|An entry in the chocolate cake
contest celebrates Yayoi
Kusama's art in the garden..
Sugar Shack entered the cake baking contest with a fabulous concoction of miniature Yayoi Kusama flowers and pumpkins, while the Cruz sisters – Isabella, 5; Victoria, 10, and Christina, 11 – entered cakes polka-dotted with Girl Scout cookies – which they just happened to be selling outside. More cakes were on their way for later entry.
|Christina Cruz disguised as a
Girl Scout cookie.
There are real chocolate trees to buy, along with tea plants and coffee trees; cooking demos, where you can learn to make everything from chocolate chili (Saturday) to chocolate truffles (Sunday); listen to Barbara and Terry Glancy talk about tea (Saturday afternoon, 2:30), and Richard Campbell tell you how to grow coffee in South Florida.
Drink a chocolate martini and go to the chocolate spa.
There couldn’t possibly be a more sensual, satisfying festival anywhere else on the planet.
After three days of dropping
Among the damaged: Pithecellobium, Pseudobombax, Pritchardia, Podocarpus…are all the P-plants doomed? Naw. Ficus, gumbo-limbo (some), African tulip trees, some coconut palms, royal poincianas, the list goes on. The damage likely will continue to appear.
I called Steve Nock, aroid hybridizer and expert who owns
|Borneo giant shows how it
disliked the cold.
Ree Gardens with his wife Marie, to ask about my damaged and drooping philodendrons and other aroids. Cut back to the stem and use fungicide where you find soft tissue, he said.
|The black olive felt outside its hardiness zone this week
and is complaining about it.
Ragtag and bitter winds played hopscotch during last week’s cold spell and now we can watch mulch being made right in our own backyards! Several months’ supply is being dropped on the patio by the West Indian black olive tree. The bougainvillea, sacred bamboo of Bali and, alas, many of the Vanda and Bulbophyllum orchids also are donating to the cause. This is really lemonade from lemons, horticulture style!
For plants, pets and plant lovers, it was a weekend of stress. Trying to get the floodlights and heaters set up in cold drizzle was a challenge. Now comes the next event: helping the garden recover, if we're lucky.
If palm fronds turn brown, remove them. However, if only part of the frond is brown, remove that part and allow the green to stay in place. All available green is needed for photosynthesis. The same is true for fronds with brown spots of cold damage. Get out the copper fungicide (Kocide) and mix 2 teaspoons per gallon of water. Pour this into the growing point – where the spear emerges. Then repeat in 10 days. Copper fights both fungus and bacteria. Don’t use copper more than twice, however, as it may be toxic in excess.Use a micronutrient spray on the fronds once a month until summer. When temperatures warm up in spring, lightly fertilize.
Leaves on tender ornamental plants will show damage, both now and in the weeks ahead. Shrubs may manifest the damage later. Allow the damaged leaves to remain as they will protect other leaves in future cold snaps. New buds eventually will tell you where healthy twigs remain. When new buds begin sprouting later in the year and you want to prune dead branch ends, count back three new buds and make the cut at that spot to avoid distorted foliage.
Since we had a full day of cold rain on Saturday, landscape plants probably have sufficient moisture today. However, you’ll want to monitor this situation as temperatures climb. Watch for wilt, but water lightly.
|Cold bent the leaf stems and
caused water-soaked areas on
this Philodendron McDowell.
Aroids, such as more tropical elephant ears, are likely to complain about the weather by bending those big stems, turning leaves yellow or showing water-soaked areas in the leaves. Use a fungicide spray, but be careful about over-watering. Roots on these plants can lose their ability to take up water rapidly and if sitting in wet soil, they can be hit by rot. Monthly micronutrient sprays will help ornamental plants recover.
Vanda orchids are likely to drop lower leaves as a result of cold, particularly after exposure to the high winds that pummeled us. Mix 1 tablespoon of Kocide with 1 tablespoon of Dithane M-45 in a gallon of water and spray them. Cattleya orchids are better able to withstand cold, but the chilling effect of the winds on these and all other orchids will likely result in slower growth ahead.
Orchids kept inside are much better off. However, don’t forget that humidity is a lot lower inside, especially if you are running the heat. So mist the roots daily while they’re being protected from the elements.
Considering all the bluff and blowing that went on over the last two days, many plants are looking surprisingly all right. For now.
This week is bringing the coldest weather we’ve experienced in nine years.
To help prevent cold damage to your plants, cover tender plants, either with old sheets, paper or boxes. Do not use plastic, as any plastic touching leaves will carry heat into the atmosphere away from the plants.
|At night, a floodlight beams heat into the covered sealing wax palms.|
I have covered the tender palms, such as the sealing wax and Pelagodoxa henryana, with sheets and put floodlights beneath the sheets to help protect them at night. The plastic on the sides of the orchid houses has been rolled down, and we have convection heaters and flood lights going inside all night. You can run water across the floor of your covered house to keep the temperatures up if you don’t have heaters. Mist systems installed beneath orchid benches are one way that commercial growers keep their orchids warm. When the sun warms the interior of your plastic-covered shade house, open a vent near the ceiling to let out hot air.
All the vandas have been moved from their trellis into a covered shade house and are sharing space with bulbophyllums and slipper orchids. We are not watering for the duration, but I will slip beneath the plastic into the house and mist the Vanda roots tomorrow.
Fortunately, I gave all the orchids a fungicide spray last week after stocking up on Dithane M4 and Thiomil (a systemic fungicide) and Kocide, an antibacyerial copper-based product. When warm weather returns, it’s a good idea to spray orchids with a mixture of Dithane M45 and Kocide, 1 tablespoon each per gallon. (Avoid using copper on bromeliads as it can be toxic to them.)
|Sheets in the garden signal
If you live in an area that is touched by frost or freezing weather this week, this same mix can be used on your palms to help prevent crown rot. Just pour it right into the growing point. Another strategy for especially tender small palms is to wrap the crown with sheets of foam to protect the heart.
Watering the ground during the day to allow the sun to heat it is a good idea as well. Don’t water the leaves of plants. If you have hanging baskets in a tree, for example, pull back mulch and water the area beneath the canopy. This will help create a warmer microclimate at night as the soil releases its warmth.
Bring inside those plants you value. I have brought in all the vandaceous orchids in flower or bud (as well as some that are prized favorites), the amaryllis, poinsettias and tender aroids, such as Philodendron tenue and Philodendron regale.
Inside also are the parrots, and they’re not at all pleased.