GROWING BROMELIADS OUTDOORS

Transcription

1 GROWING BROMELIADS OUTDOORS Bromeliads are very useful landscape plants in Hendry County. Since bromeliads require minimal care, they are an asset in the landscape. If left to multiply freely most bromeliads will crowd out weeds. By and large most bromeliads are hardy to the 27 degrees occasionally seen in LaBelle. Only certain types of bromeliads, Vrieseas and Guzmanias, require protected positions in LaBelle. Bromeliads are generally epiphytic. However, because of the sandy free draining soils of much of Hendry County these epiphytes will grow well in the soil as terrestrial plants. Most of my bromeliads are growing in the ground. Note I grow only a few tillandsias, which generally won t grow in the ground. A fascinating use of bromeliads is to grow them as tree decorations on the trunks and limbs of trees. Typically the plants are tied onto a limb or a trunk using nylon filament or aluminum wire (DON T USE COPPER WIRE, IT KILLS THE BROMELIAD). I prefer aluminum wire and a little glue as birds seem to like monofilament for their nests. After a while the plant attaches itself firmly to the tree with aerial roots and the wire can be removed. Some bromeliad species grow right up the tree trunk while others will form a large clump on a limb. An old live oak filled with these plants can be quite a sight. VARIETIES OF BROMELIADS Few families in the plant kingdom surpass bromeliads with their wide variation in size, shape, and foliage color. Bromeliads are in the pineapple family (Bromeliaceae), a family native to the American Tropics. Two widely known members of this family are pineapple (Ananas comosus) and Spanish moss (Tillandsia usneoides). The majority of bromeliads grown are epiphytes. In their native habitats, they attach by special root structures to trunks and branches of trees and derive their moisture and nutrients from the air and rain. Some are called saxicolous because they attach themselves to rocks, while the rest are terrestrial and grow in the ground as most plants do. Plants in the family Bromeliaceae vary widely in shape, size and color. Even species of a single genus often differ drastically in appearance. Most bromeliads cultivated however, are alike: without stems and with a central flower spike and strap-shaped, leathery, arching leaves arranged in a rosette. Most species are grown primarily for their colorful foliage and exotic shapes. Many others are grown for their huge and often bizarre flowering spikes. Variations in foliage are as wide as those in flowering, and leaves may be green, gray, maroon, spotted or striped. Leaves range from grass-like and less than 2 inches long in some tillandsias, to broad and several feet long in billbergias. The upper leaves of many species change color when plants are about to flower. The gray-green, grass-like foliage of Tillandsia ionantha turns pink, and deep purple-blue flowers arise among the pink leaves. "Inflorescences (the flowering parts of a plant) may arise from the "cup" or be borne within the "cup." The "cup" or the "vase" is a water holding tank or reservoir formed in the center of many bromeliads by a rosette of overlapping leaves.

2 Flowers are often small but colorful; however, the showy portion of the inflorescence is frequently made up of brilliantly colored bracts borne below each flower. Bracts maybe separated, large and leaf-like or overlapping, forming dense spikes. Usually, the bright bracts remain on the inflorescence while fruit matures. The combination of highly colored bracts and often contrasting colored fruit, which remains on the plant for several months, adds to the aesthetic value of bromeliads. CLASSIFICATION The bromeliad family (Bromeliaceae) consists of 51 genera and about 1,500 strictly American species. They grow from the dry deserts of southwestern United States to equatorial tropical rainforests of the Amazon. Based on growth habits and other characteristics, Bromeliaceae is divided into the subfamilies Pitcairnioideae, Tillandsioideae and Bromelioideae. Members of the subfamily Pitcairnioideae are mainly terrestrial plants with heavy spines on their leaf edges. They grow in soil or on rocks and do not have a leaf rosette that traps water. The genera belonging to this subfamily commonly cultivated are Dyckia, Hechtia and Puya. These are generally desert plants rarely grown outdoors in Hendry County except as rock garden subjects (they grow well with agaves and are hardy). The genera Pitcairnia is unique to bromeliads in that it grows more like a daylily with broad, grass-like stalks which are generally spineless. It typically prefers a moist but well drained acid growing media and is rarely planted outside in LaBelle. The subfamily Tillandsioideae contains the least number of genera but the largest number of species, of which many are cultivated. Plants in this group have smooth or entire leaf margins, unusual foliage markings and colors. Some species produce fragrant flowers. Plants in the genera Guzmania, Tillandsia and Vriesea are the more commonly cultivated members of this subfamily. These genera are the most sensitive to cold and generally need some winter protection, such as being shaded by a large tree or being within four feet of the house. Bromelioideae, the third subfamily, has the most bromeliad genera grown in the garden. It encompasses 30 genera with the widest range of plant forms, and accordingly the largest number of cultivated species. Subfamily members are mostly epiphytic, leaf edges are almost all spiny, foliage has attractive markings and patterns, and the leaves are usually arranged in rosettes which may be cup-shaped. Aechmea, Billbergia, Cryptanthus, Neoregelia, Nidularium and Quesnelia are the most popular genera of this subfamily. These genera tend to be relatively cold hardy and survive in LaBelle even when exposed to the elements. COMMONLY GROWN GENERA Aechmea. Most of the 150 species in this genus are epiphytic, have deep cups to hold water and outstanding foliage all year long. The leaf edges are spined. The spines of some of the sun loving varieties are really wicked. Aechmea fasciata, one of the most popular bromeliads, is often called the urn or living vase plant because it appears to have provided a vase for its predominately pink inflorescence (it generally doesn t have

3 spines). These are very common landscaping bromeliads often grown in full sun in Hendry County. Their flower spikes can be wonders to behold. Some varieties also have yellow, orange, red and deep burgundy foliage. They also have variegated foliage. Aechmeas like foliar fertilization. Ananas. The commercial edible pineapple (Ananas comosus) is a member of this genus. There is a variegated form of this species (Ananas comosus variegatus) that has green, cream and pink striped leaves that form rosettes 2 feet or more across and be either well spined or spineless. These are true terrestrials that cannot be grown in trees and require fertilized soil to grow well. The spined variegated form is a common landscape plant in Hendry County. They can grow in full shade to full sun. The more sun they have the more colorful the leaves are. We can grow pineapples to maturity in LaBelle, you just need to pick them before the raccoons get to them. Billbergia. Billbergias are tall and urn-shaped with spiny edged leaves. They are usually epiphytic and the foliage is often attractively variegated, banded or mottled. Fancy mottled purple leaved hybrids grow especially well in trees, where their mottled leaves and color can be appreciated from below. Although short-lived, inflorescences are very colorful. They are hardy and grow well in the sandy soil of Hendry County. They are common landscape plants, especially the common grey green (Billbergia nutans) form of the plant which is a definite hand-me-down plant. Billbergia pyramidalis is so common it is decidedly the most common bromeliad in South Florida. Its pale green leaves give it an almost weedy appearance but when it blooms in mass in August with its flamboyant pinkish orange flowers it is anything but weedy. It is called the "hurricane bromeliad" because of its August bloom. Cryptanthus. These plants are small, terrestrial, sometimes stoloniferous with flat, basal, symmetrically arranged, variously colored brown to black to brick red to green leaves with zones of grey fuzz and sometimes strips. They are grown mainly as foliage plants but their tiny white flowers, emerging low in the rosette of leaves, are very attractive. The leaves do not form a cup and don t hold water. Plants of this genus are commonly referred to as "earth stars" because their leaves grow low and parallel to the ground in a star-like arrangement. These plant grow naturally in swamps and don t do well in most of our sandy soils. They typically need to be grown in pots with African violet type water retaining media and kept moist. Guzmania. Bromeliads in this genus have thin, glossy, strap-like, smooth-edged leaves which form a water-holding rosette. There are thin brown, purple or maroon lines which run parallel along the length of the leaves. Clusters of red, white or yellow flowers appear from behind orange, yellow or red bracts on a terminal spike. They are mostly epiphytic, however, a few are terrestrial. All grow well in our sandy soil in a protected position. Guzmanias are the yellow, orange and red bracted plants so commonly found at home improvement store next to the orchids. Guzmanias are unusual in that the pups come up within the leaves of the mother plants, making division much more difficult. It is easiest simply to grow these as a clump of many plants. Not widely planted in LaBelle because of its tenderness to frosts.

4 Neoregelia. These epiphytic bromeliads develop blue or white flowers just above the water level in the cup. The central portion of the leaves surrounding the flowers can turn all shades of red and orange. The spiny-edged leaves may also have red spots, markings and linear variegation. Some of the species (Neoregelia spectabilis) develop red leaf tips and are often called "painted fingernail." These painted fingernail plants are one of the most common bromeliads found in the soils of Hendry County, especially as hand-me-down plants. Members of this genus are grown largely for the many colors of their foliage. There are bright red, orange and even pink hybrids with all sorts of spots and white streaks. If these plants (and other foliage bromeliads ) are fertilized they often lose their color in their leaves. Some of the pinks and light red hues lose their color if exposed to any direct sunlight. Any large neoregelias showing the painted fingernail on their tips of their leaves (many hybrids show these red tips) will generally grow in full sun and are quite hardy. Nidularium. Plants in this genus are often confused with those in the genus Neoregelia. They both have bird's nest type flower heads; however, Nidularium inflorescence shows the bracts rather distinctly while the inflorescence is buried in the leaf rosette of Neoregelia. I.e. Nidularium has a neck below its flower rosette. These medium-sized, epiphytic plants have broad, flexible, lightly spined leaves that form an open rosette. These are rarely seen in Hendry County although they grow well in the sandy soil in a sheltered position. Quesnelia. Another light green weed bromeliad common throughout Hendry County with a pink flower very similar to Billbergia pyramidalis. The major difference is that this plant flowers in the winter. Tillandsia. With nearly 400 species this genus is the largest, most diverse and widely distributed genus in the bromeliad family. Most are epiphytic, except for a few species that grow on rocks. Plant species vary in size from tiny to large. Some species have leaves that are tough and string-like; others have soft, thin, strap-like leaves. In still other tillandsias the lower part of the leaf is spoon shaped. Often, the leaves are covered with a gray fuzz or scales. Spanish moss is a tillandsia with a tiny green flower. The inflorescence is spectacular in some species consisting usually of blue flowers with brightly colored bracts. The entire plant will often turn red or pink at flowering time. Tillandsias as a group require high air circulation and will not grow on the ground. Most people who collect them grow then on wood suspended in trees or a greenhouse. They like foliar fertilization. Florida has some eight species of native tillandsias. Vriesea. With more than 200 species this genus is the second largest but most hybridized and cultivated genus in the bromeliad family. These are medium size, mostly epiphytic plants with soft or firm, variously green but often spotted, blotched or distinctly marked leaves. The usually long-lasting inflorescences have yellow, green or white flowers and brightly colored bracts. The inflorescences may be upright like a spear, pendulous or even curved. Plants in this genus are very susceptible to injury from cold

5 temperatures. They will grow in sheltered locations in the sandy soil of Hendry County but they are rarely encountered. LIGHT Bromeliads tolerate a wide range of light intensities, including low light, for long periods without ill effects. The plants, however, will look better when they receive proper light. Although optimum light levels vary considerably, the following characteristics are helpful in selecting a spot for a particular plant. Generally bromeliad species with hard, thick, gray, gray-green or fuzzy foliage and wicked thorns withstand the highest light levels, while species with soft, green, thin thornless leaves grow best under lower light levels. In most instances, a bromeliad will indicate by its growth habit whether light levels are satisfactory. A yellowish or pale green plant may indicate that the light level is too high. Conversely, a darker green than normal, with a more open or elongated shape, may indicate low light levels. It is difficult to categorize bromeliad genera into optimum light levels, because light requirements of species within a genus may differ. The following generalizations can be used as a guideline, however, when selecting bromeliads for a particular site. Plants in the genera Dyckia, Puyas, Hechtias, Ananas and the hard-leaved species in Aechmea and Billbergia grow best at high light levels. Plants in the genera Guzmania, Neoregelia, Nidularium, Cryptanthus and Vrieseas can grow under lower light levels. In general, the larger and more spiny the plant the better it will withstand high light conditions including full sun. AIR CIRCULATION Bromeliads, due to their epiphytic nature, require good air circulation. Fresh air supplies them with carbon dioxide and moisture. Plants grown in stagnant air are more apt to be attacked by scale insects and fungal organisms causing the bromeliads to deteriorate rapidly. This is especially true of Tillandsias. Tillandsias MUST be grown in the air where air circulates freely around them. They will not survive near or in the ground. WATER Bromeliads are extremely tolerant of low-moisture conditions and will survive prolonged periods of drought. When the relative humidity is low (during winter months) plants must be checked and watered more often. Many bromeliads are formed of a rosette of broad leaves which creates a "cup" or "vase" in their centers. It is best to keep this cup filled with water at all times if growing outside. Epiphytic bromeliads, such as those found in the genus Tillandsia, are often grown secured to a board or bark. Because tillandsia have no distinct cup to collect water, they absorb moisture from the air through their scaly leaves. FERTILIZATION Actively growing bromeliads respond to applications of liquid foliar fertilizer. During the winter months, or under conditions of low light, they require little or no fertilizer. I foliar liquid feed all my bromeliads on a regular schedule with a complete foliar fertilizer and have never had any problems with fertilizer build-up in the cups. Controlled-release

6 fertilizers can be incorporated uniformly applied on the soil surface around established plants. Avoid putting any granular or pelleted food in the cups, foliage burn will result. Bromeliads usually grow much better with a continuous nutrient supply. Note that variegated leaved plants (zones, spots, stripes, mottling, etc.) will often lose their variegation when fertilized. PROPAGATION Bromeliads can be propagated by removal of "pups" or "offsets" from the "mother plant" (asexual). Bromeliads slowly die over a period of a year or two after flowering. However, several pups usually develop during the flowering cycle and usually emerge from the soil near the base of the plant after it has flowered. This pupping can be encouraged by running a knife through the middle of the mother plant, right down its core. Multiple pups will generally start growing following this procedure. The pups should be separated from the mother plant after they have developed a small rosette of leaves similar to the mother plant about one half to two thirds the size of the mother plant. To remove a pup, use a serrated knife, pruning shears or small saw. Coarse hacksaw blades may also be used for this purpose. Push the saw blade into the growing medium, between the pup and mother plant, and cut through near the base of the mother plant. The young pup may or may not have developed a root system of its own. Don't be alarmed if it hasn't. On plants growing in sandy ground simply stick the pup in the ground where you want it to grow and it will develop new roots on its own. Alternatively you can just leave the pups in place and allow the single plant to become a large clump of plants. The mother plant, especially if helped along with a small amount of foliar liquid fertilizer in its cup, will continue to produce pups until it dies. These pup plants will normally flower in 1 to 3 years. Propagation by vegetative means (pups) is by far the best and most satisfactory method for home gardeners. Growing seed is a long and difficult process. Since most popular plants are complex hybrids they often don't produce viable seed. And 99% of the time the color and flower of the seedling doesn't equal that of the parent. DISEASES Many problems commonly attributed to diseases are the result of unfavorable growing conditions. Low temperatures (40 F and below) and overwatering can cause the crown of many bromeliads to rot. Also, plants subjected to mechanical injury, insects or sunburn may be invaded by one of many fungi. This invasion usually appears as a dark spot on the leaf, either with sunken or water-soaked areas, or frequently with a radiating yellow area. Fungicides of any type should be used with extreme caution on bromeliads, just as on orchids. Bromeliads appear to depend on some beneficial fungi for water and food and fungicides can upset this balance. Note that copper containing fungicides should never be used in bromeliads. Even minute amounts of copper kills bromeliads.

7 INSECTS Few insects bother bromeliads, and those that do can be controlled. A number of scale insects attack bromeliads. Appearing as small round or oval objects on the leaves, scale insects multiply rapidly. They make plants unsightly by producing yellow spots on the leaves where the insects suck plant juices. Mealybugs and root mealybugs, both characterized by their cotton-wool protective covering, may also attack bromeliads. When mature, mealybugs vary from 1/5 to 1/3-inch long and some species have long wax filaments extending from the rear of the body. They damage bromeliads by sucking plant juices. Systemic insecticides are the most effective defense against scale and mealybugs. There is a weevil which has been introduced from Central America which has decimated the native tillandsias. Thus far this weevil has only rarely attacked nonnative hybridized bromeliads. It seems to prefer the subfamily Tillandsioideae. But if plants are attacked the weevil grub eats out the living core of the plants and the plant just falls apart. The only defense is using systematic insecticides often. Spider mites may also attack bromeliads. They are about 1/50-inch long when mature and may be greenish, yellowish, reddish or virtually colorless. Commonly found on the undersides of leaves, they suck juices from plants through their needle-like mouthparts. A 10- or 15-power hand lens is very helpful in detecting infestations before severe damage occurs. Tiny cobwebs are a sure sign of spider mites. Spider mites can be controlled with soap and alcohol washes and are rarely found on outdoor plants, being generally well controlled by natural predators. A NOTE OF CAUTION There are some genera of bromeliads that are so spiny I rate them as downright dangerous. One common such genera is Bromelia. The most commonly planted species is Bromelia balansae whose center becomes bright red when in bloom. This plant is used as cattle fencing in South America. It makes barbed wire look harmless by comparison. Once planted, it will spread and take over an area. It s very hardy, fast growing and difficult to eradicate once it gets going. I do not recommend planting it. BROMELIAD SOCIETY There is a bromeliad society which meets down in Fort Myers on the third Sunday of every Month. It is the "The Caloosahatchee Bromeliad Society" and further information can be obtained from David Bogert at This article is based on an article by Robert J. Black and Bijan Dehgan of the University of Florida IFAS Network David Bogert DLBoge2@gmail.com