A croton primer

Tue, Jan 26, 2010 at 01:39:53 PM

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
shade.

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.

6 comments - Add a comment

I've noticed more leaf-drop from the cold spell on the curly-leaf variety of croton in my Ft. Lauderdale garden than on the broad-leaf varieties.

I don't know if this is a generalization that will hold true for all curly-leaf crotons, or just those particular ones in my garden.

posted by Michael, Tue, Jan 26, 2010 at 8:42 PM

I only have two curly-leaf crotons, and both are Thai hybrids. One lost leaves and one didn't, so I figured it was the exposure. I'll keep an eye out in the neighborhood.

posted by Georgia, Thu, Jan 28, 2010 at 7:06 AM

I've walked around my fairly large complex (11 acres, 22 buildings) in the Ft. Lauderdale area, where there are many different varieties of croton planted. I'm not an expert on the different varieties of croton, and can tell you that exposure is definitely a factor.

However, all that being said, the greatest damage I have seen to date on scores of crotons on this property, has been primarily to the curly-leaf crotons, and thin-leaf varieties. I have seen lesser damage to broad-leaf varieties, and have noticed ZERO damage to the several Gold-Dust varieties of crotons which are planted throughout the complex.

So, what's interesting to me, is that within the same species, there seems to possibly be variance to cold-tolerance according to cultivar.

posted by Michael, Thu, Feb 4, 2010 at 11:42 AM

As with Dieffenbachias (and maybe Heliconias too), this would be an interesting topic to get some input from commercial growers of croton, as to whether they noticed a difference between cultivars in their stock.

posted by Michael, Thu, Feb 4, 2010 at 12:01 PM

My croton is coming back after being severely attacked by scale and losing its leaves in the cold. The new leaves look very healthy. Has anyone else seen this? Does this mean that croton scale may be abating?

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posted by Joe Cast, Tue, Oct 12, 2010 at 10:56 PM

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Georgia Tasker

Georgia Tasker was the garden writer for The Miami Herald for over 30 years and has written four books on gardening. Her blog is a must read for any gardener.