Crotons : Codiaeum (koe-dih-EE-um or koh-dee-EYE-um)By Marie Harrison (can2grow)
June 3, 2010
Crotons (Codiaeum) are members of the Euphorbiaceae family. The number of species varies according to which taxonomic authority is consulted. APG II of the GRIN website lists one species, but two varieties are given. Dr. Frank Brown ED.D, author of A Codiaeum Encyclopedia, Crotons of the World, also states that there is only one species. Wikipedia mentions about 16 species. However, the different opinions do not disturb most gardeners, for the number of cultivars from which one can choose is astronomical.
Crotons are native to southern Asia, Indonesia, and other eastern Pacific islands where it grows in open forests and scrub areas. It is important to remember that croton is the common name of the species, and that the scientific name is Codiaeum. The genus should not be confused with another group of plants with the scientific name of Croton, which are also in the Euphorbiaceae family. The genus Croton contains more than 700 species of herbs, shrubs, and trees, some of which are native to North America. In this article, where croton is not in italics, the word refers to the genus Codiaeum.In nature, croton is a broadleaf evergreen shrub that grows up to 12 feet tall. Leaves are large, leathery, and glossy. The first croton (Codiaeum ‘Mollucanum') had all green leaves. From it a sport was produced that had variegated leaves. This second cultivar was C. ‘Aureo Maculatum', which in turn sported another cultivar, C. ‘Punctatum'. Since seedlings of crotons do not come true to form, seedlings of these three cultivars produced many new variations. Ultimately, hundreds of selections are now available worldwide as a result of sports, seedling variability, and extensive hybridization.
Crotons are usually grown for the colorful foliage that may include white, purple, orange, yellow, red, or pink. Colors may follow the veins, the margins, or they may be in blotches on the leaf. Star-shaped flowers are tiny and inconspicuous and hang down in long racemes. Bees seem not to care for the flowers, but they are popular with ants upon which they depend for pollination. Like other members of Euphorbiaceae, the stem bleeds a milky sap when cut.
Crotons are tropical plants, so they do best with warmth and humidity. Best leaf color develops when planted in shifting sun. If planted in deep shade, the colors will be mostly green. In too much sun, the colors will fade. Soil should be well- drained, but enriched with generous amounts of organic matter. Plants thrive when fertilized regularly with a general purpose fertilizer or one formulated for acid-loving plants, such as azaleas and camellias. In the landscape, a high nitrogen fertilizer is preferred during the growing season to promote leafy growth, but during the cool season, a fertilizer that has more phosphorus and potash strengthens the plant and protects it from seasonal cool spells. Even so, severe damage can result if the temperature falls down around 46°F for an extended time.
Water regularly during the growing season, but back off a bit during the winter. Never let the plants dry completely out. They will announce their need for water by wilting.
PestsCrotons may be attacked by scale insects, thrips, mealybugs, and mites, but their worst enemy seems to be the red spider mite. This harmful spider pierces the leaves with sharp mouth parts and causes the colors in the leaves to fade. A severe infestation can diminish the strength of the leaves significantly, and may even cause them to fall off. Often the spider mite population is kept under control in the landscape by a sprinkler system that keeps them knocked off. Severe infestations are usually seen indoors where the leaves are not frequently rinsed by the irrigation system or rain. Most of these insects can be controlled with a strong jet of water from the hose. If the infestation is severe, use a product that is formulated for the specific insect that you need to control.
Crotons in the landscape and in containers tend to get leggy with age, and they are likely to produce the most foliage at the top of the plant. Cut leggy plants back to encourage new growth. Good results can be obtained by pruning about one-third of the branches and then waiting until new grown has started before pruning the next third of the plant. By the time the final third is cut, a newly compact and bushy plant should be well on its way. Pinching out new growing tips will encourage branching and result in a fuller specimen.
New plants can be started by air-layering, by cuttings, or by seeds. Cuttings root easily when placed in damp soil. When you prune, try rooting the cuttings for additional plants.Crotons exhibit in a wide variety of leaf shapes.
Crotons in the Landscape
Crotons make attractive hedges and potted patio specimens in tropical areas. They make attractive foundation plants, accents or specimens, and they grow great in containers. Where crotons are not hardy, grow them in containers and move them inside during the winter. Place the container in a bright window with a southeast or southwest exposure, but not in direct sun. Protect from drafts and fluctuations in temperatures.
However you choose to grow crotons, rest assured that they will draw many compliments from admiring onlookers. They are among the world's most colorful and strikingly beautiful leaved foliage plants.
'Spirale' - spirally-twisted red and green leaves
'Andreanum' - broadly oval yellow leaves with gold veins and margins
'Majesticum' - 10-inch long linear leaves with midrib veins yellow maturing to red
'Aureo-maculatum' - green leaves spotted with yellow
‘Angustissimum' - narrow leaves with yellow margins and ribs
‘Aucubifolium' - broad yellow, red-blotched leaves
‘Interruptum' - twisted, yellow leaves with red midrib
‘Sanderi' - broad leaves, irregularly blotched
‘Weismannii' - narrow, wavy-margined leaves, variegated with yellow, red petiole
Nine leaf types are generally recognized, though there are variations of all of them.
1. broad leaf croton - large and broad leaves
2. oak leaf croton - looks like a true oak leaf
3. semi-oak leaf croton - indistinctly lobed, many variations
4. spiral leaf croton - leaves that are twisted, either right, left, or partially
5. narrow leaf croton - a width of about 2 to 4 inches and length usually 2 to 4 times the width
6. very narrow leaf crotons - usually ½ inches wide or less and are long and droopy
7. small leaf crotons - have the original shape, but maximum length is about 2 inches
8. interrupted leaf croton - unusual because the leaf blade stops, the midrib continues for about 1", then leaf blade continues
9. recurved leaf - leaves curl back on themselves, scarcest leaf type