Research about sansevieria

SANSEVIERIA
The genus Sansevieria, a member of the agave family (Agavaceae) contains approximately 60 species indigenous to Africa, Arabia, and India. Several species and their cultivars are grown commercially for use as interior foliage plants. Indoors they may be used in floor level planters, small specimens, dish gardens and other combination planters, and occasionally in hanging planters. Sansevieria use depends upon growth habit, texture, and color of the plant.
Sansevieria trifasciata and its cultivars have been important foliage plants in Florida since the late 1920's. More than one-half of the sansevieria produced in Florida during the 1930's were shipped to Europe. Today bare-rooted plants are imported from the Caribbean Islands and Central America because of their low production costs. In 1956 sansevieria constituted 16 percent of the total foliage plant mix produced in Florida, but by 1975 they accounted for only 3 percent.
The 3 categories of sansevieria produced by Florida growers are bare-root divisions from established bed-grown plants, bare-root plantlets removed from rooted leaf cuttings, and finished container-grown plants.
SPECIES AND CULTIVARS
Most commercially important cultivars were selected from Sansevieria trifasciata. A few out-of-state specialists list 20 or more sansevieria species and cultivars in their catalogs.
Sansevieria cylindria, the spear sansevieria, has a thick rhizome supporting rosettes of 3 to 4 leaves, each 2.5 to 4.5 feet long by 0.7 to 1.2 inches wide. The medium green leaves with dark green cross-banding are nearly cylindrical and slightly thicker from front to back than from side to side. Small plants propagated from leaf cuttings have some reflexing leaves in each rosette. Rosettes from established clumps produce predominantly straight, erect leaves.
Sansevieria parva, sometimes called Kenya hyacinth, is a relatively fine-textured species with narrow, reflexing leaves about 8 to 16 inches long and 0.5 to 1 inch wide. Rosettes are composed of 6 to 12 medium green leaves with dark green cross-bands.
Sansevieria trifasciata, also called snake plant, mother-in-law's tongue, or common sansevieria, has up to 6 leaves per rosette. Mature leaves are dark green with light gray-green cross-banding, and usually range between 2.5 and 3 feet in length and 2 to 2.8 inches in width. Leaves which develop under bright light out of doors or in bright greenhouses have prominent light cross-bands, while those which develop under 2000 foot-candles or less, or are held under low light intensities, have nearly solid dark green leaves. Most plants sold as Sansevieria zeylanica are S. trifasciata. True Sansevieria zeylanica has little appeal as an ornamental.
Sansevieria trifasciata `Bantel's Sensation' or white sansevieria, is marked with an alternating and variable pattern of longitudinal white and dark green stripes. Leaves are stiffly erect and both narrower and slightly shorter than those of the species. Some leaves with wide green sectors may have transverse-banding of lighter green similar to that of the species.
`Bantel's Sensation' is a sport of S. trifasciata `Laurentii' which was discovered by Gustav Bantel of St. Louis, Missouri and patented (Plant Patent No. 796) in 1948. (A United States Plant Patent is granted for a term of 17 years from the date of its issue). Its slow growth rate has limited its production to a few growers specializing in unusual plants.
Sansevieria trifasciata `Futura' is similar to S. trifasciata `Laurentii' but has shorter, broader leaves, more leaves per rosette and, typically, a narrower yellow margin, approximately 0.1 to 0.2-inch wide. The growth habit of `Futura' closely resembles `Moonshine'. `Futura' is a relatively new cultivar which is well received by consumers. When `Futura' is propagated from leaf cuttings, practically all plantlets formed are green with silvery green cross-bands, but lack the yellow marginal stripe. However, they do retain the broad-leafed, robust growth habit typical of `Futura', and in this guide are called `Robusta'.
Sansevieria trifasciata `Golden Hahnii', golden birdnest sansevieria, has attractive green leaves with a combination of marginal and internal yellow stripes of variable width which are parallel with the veins. Discovered by Sylvan Hahn `Golden Hahnii' was issued a plant patent (Plant Patent No. 1224) in 1953. Producers have not attempted to grow `Golden Hahnii' extensively because the pattern of variegation is rather unstable and growth rate is slow.
Sansevieria trifasciata `Hahnii', birdnest sansevieria, has attractive short, dark green, reflexed leaves which form a vase-shaped rosette. Leaves have similar banding patterns as the species, but `Hahnii' and the other birdnest cultivars of S. trifasciata are not known to flower. Birdnest sansevieria, a sport of S. trifasciata `Laurentii', was discovered by William
W. Smith, Jr. in the Crescent Nursery Company, New Orleans, Louisiana in 1939 and was patented in 1941. The patent (Plant Patent No. 470) was assigned to Sylvan Hahn, Pittsburgh, Pennsylvania.
Sansevieria trifasciata `Laurentii', the goldband sansevieria, has an upright growth habit as the species but features a showy golden yellow leaf margin which is somewhat variable in width and position. `Laurentii' was introduced from the Belgian Congo. Although there are several relatively new cultivars of sansevieria which are increasing in popularity, goldband sansevieria has been and is still by far the most popular ornamental sansevieria.
Sansevieria trifasciata `Laurentii Compacta', the compact goldband sansevieria, is a selection maintained by a few producers. `Laurentii Compacta' has shorter leaves with darker green coloration between the gold bands than `Laurentii'.
Sansevieria trifasciata `Moonshine', Moonshine sansevieria, is a relatively new cultivar which features broad, nearly solid, light silvery gray-green foliage with a tracery of dark green around the margin. Plants grown in deep shade have darker leaves. `Moonshine' plants, also sold as `Moonglow', usually have 3 or more upright leaves giving individual divisions a vase-like form as the leaves diverge slightly from the center of rosettes. `Moonshine' is identical in growth habit and vigor to `Futura' and `Robusta'.
Sansevieria trifasciata `Nelsonii', Nelson's sansevieria, is a sport from S. trifasciata `Laurentii' which was patented (Plant Patent No. 633) by Oscar Nelson of Miami, Florida in 1944. Its solid dark green leaves have a velvet-like sheen and stiffly erect habit of growth. Leaves are shorter, thicker, and more numerous per rosette than the species. Its slow growth rate makes it relatively rare in the trade. There are two nearly identical forms, one of which is `Nelsonii'. `Nelsonii' propagates true to type from leaf cuttings while the other form, also sold as `Nelsonii', must be propagated by rhizome division because leaf cuttings yield S. trifasciata. The latter type is most widely distributed.
Sansevieria trifasciata `Robusta', the robust sansevieria, resembles `Futura' but lacks yellow leaf margins. Leaves are about 30 percent shorter and 1.5 to 2 times wider than S. trifasciata, with essentially the same color and pattern of leaf cross-banding as the species.
Sansevieria trifasciata `Silver Queen', silver queen sansevieria is an upright cultivar similar to the species. New leaves are nearly solid silvery gray-green with thin dark green margins. Older leaves darken, and plants in low light darken sooner.
Sansevieria trifasciata `Silver Hahnii', the silver birdnest sansevieria has medium silvery gray-green leaves with indistinct transverse green bands through silver coloration and fine dark green margins. `Silver Hahnii' originated as a sport of `Hahnii' in New Orleans and was patented (Plant Patent No. 1220) in 1953 by Sylvan Hahn. Its growth habit is nearly identical to that of `Hahnii'.
PRODUCTION
Plantings in Open-Field
Propagation by Division
Open-field sansevieria production is concentrated in the southern part of Dade County near Homestead, where severe cold injury is rare. Most open-field stock beds in Dade County are planted in limestone soils classified in the Rockland association. The solid limerock surface is fragmented with a heavy rock plow and crusher to a depth of approximately 4 inches prior to planting. Most of the limerock soils range in pH from 7.5 to 8.5 and are very well drained.
Sansevieria are planted in beds 3.5 to 4.5 feet wide. New beds are usually planted with single-rosette divisions on approximately 10- to 12- inch centers. Plants branch at and just below the soil surface and reach full production 1.5 to 2 years after planting, depending upon initial plant spacing, fertilization rate, irrigation schedule, and quantity of plants harvested before beds are fully productive.
Harvesting bed-grown sansevieria is a selective thinning process. Single rosettes of desired size are severed from the remaining clump by hand with a weeding knife or similar cutting tool, and lifted from the bed. Fully productive beds are harvested 5 to 6 times per year to prevent crowding of young plants which distorts new rosettes. Beds which become excessively crowded or are severely damaged by cold or hail can be rejuvenated by mowing 2 inches from the ground. Some sansevieria stock beds in Florida have been in continuous production for approximately 50 years.
The surface of harvested bare-root plants should be dry before packing to reduce the chance of bacterial soft rot in shipment. Tall cultivars are separated into 6 grades of 3-leafed divisions according to height; 6-9, 9-12, 12-15, 15-18, 18-24, and over 24 inches Graded bare-root plants are usually wrapped individually in newspaper and packed tightly in cardboard shipping cartons. Proper packing techniques reduces damage from plants shaking loose or cartons being crushed.
Plantings under Structures
Propagation by Division
In central Florida and parts of south Florida sansevieria are grown in greenhouses or in shadehouses lined with polyethylene and heated during winter. Plants are grown from division of stock or from leaf cuttings, depending upon the cultivar and size plant desired. Stock bed width and harvesting procedures are similar to open-field production. One exception is that the sandy soil is usually rinsed from roots prior to packing, a procedure not usually required when plants are grown in limerock.
Sandy field soils used for ground beds should be amended with 15 to 20 percent peat incorporated into the upper 4 inches to improve water holding and cation exchange capacity. The pH of most sandy ground beds in central Florida ranges between 5.5 and 6.8.
Research has shown that S. trifasciata growing in beds of sand and peat in central Florida will yield 24 or more plants per square foot per year, with an average weight of 0.29 pound per plant. Nonvariegated plants are generally more productive than variegated cultivars of the same species.
Propagation by Cuttage
Some nurseries grow small plants from leaf cuttings in either ground beds or raised benches. Leaf cuttings of nonvariegated cultivars are usually stuck in early spring and yield small plants in autumn under shadehouse conditions.
Cutting size is determined by plant growth habit and propagator preference. Propagators of dwarf types such as S. trifasciata `Hahnii' utilize entire leaves 3 to 4 inches long, while leaves of taller types are cut into 4- to 8-inch sections. Shorter sections yield fewer plantlets per cutting and require more time in propagation.
There is little if any benefit from use of rooting hormones on sansevieria. Cuttings must be stuck with their basal ends down approximately 1 to 1.5 inches into a well drained but moist medium. Since the upper and basal end of cuttings taken from the mid-section of taller types is difficult to determine visually, it is often desirable to mark or notch one end of the cuttings consistently to aid in sticking. Cuttings stuck upside down will not develop roots. A mixture of sphagnum peat and coarse sand (3 to 1 by volume) or a similar mixture is satisfactory for rooting in raised benches. Cuttings can also be rooted in trays 3 to 4 inches deep. Roots initiate and begin to develop within 4 to 6 weeks if the medium is kept warm - between 70 to 75øF - and one or more leaves emerge from the propagation medium surface within another 3 to 4 months. The propagation medium should not be kept wet, or cuttings may become infected with bacterial soft rot. Root and shoot development occurs more slowly at lower temperatures; temperatures below 60øF should be avoided. Depending on cultivar, cutting size, section of leaf used, and its physiological conditions, leaf cuttings will usually produce 1 to 5 plantlets. Plantlets should be broken or cut from the leaf cutting when they reach the desired sized. Variegated cultivars such as `Laurentii', `Futura', `Golden Hahnii' and `Bantel's Sensation' must be propagated by rhizome division rather than leaf cuttings to retain desired variegation.
Since several sansevieria cultivars are periclinal chimeras, they do not propagate true to type from leaf cuttings. Types which should be propagated from crown division only and those which may be produced from either crown division or leaf cutting are indicated in Table 1. The first few leaves to develop on sansevieria propagated from cuttings are juvenile and lack the typical foliage shape characteristic of mature plants. Juvenile leaves on many sansevierias are shorter and more reflexed than mature leaves. Plants from rhizome divisions usually produce leaves typical of mature plants.
Table 1. Propagation techniques for selected species and cultivars of Sansevieria. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Plant name Plant techniquez Comments
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Sansevieria Crown Leaf
division cutting
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
S. cylindrica + + -
S. parva + + -
S. trifasciata + + -
S. trifasciata + O Usually reverts
`Futura' to `Robusta'
S. trifasciata + O Usually reverts
`Golden Hahnii' to `Hahnii'
S. trifasciata `Robusta' + + -
S. trifasciata `Hahnii' + + -
S. trifasciata + O Usually reverts
`Laurentii' to S. trifasciata
S. trifasciata + O -
`Laurentii Compacta'
S. trifasciata + O Usually reverts
`Moonshine' to `Robusta'
S. trifasciata `Nelsonii' + + -
(original cultivar)
S. trifasciata `Silver-Queen' + + -
S. trifasciata `Silver Hahnii' + + -
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
z Plants propagate true to type = +;
plants do not propagate true to type = O.
Propagation by Seeds
Although several species can be propagated from seed, this technique is not employed because the large number of seeds needed by commercial growers is not available and normally plants can be produced faster by cutting or division.
Potted Sansevieria Production
Potted plants are available in container sizes from 2.5-inch square to 14-inch diameter, depending upon the cultivar. Most container-grown sansevieria are produced in shaded greenhouses where temperature, nutrition, diseases, and pests can be controlled. Small plants propagated from leaf cuttings are most suitable for use in 2.5- to 4-inch containers. Plants used in larger pots are normally propagated by division of bed-grown stock.
No particular grades exist regarding number of sansevieria rosettes per container. Most growers use enough plant material in each container to give a balanced appearance to the finished product. Plants should be grown until roots have become well established before they are sold. Usually 3 to 5 weeks is sufficient. Plants from open-field stock beds in limerock usually have fewer roots and establish more slowly than plants from beds or benches containing peat. Container-grown sansevieria should not be permitted to become root-bound, because they soon send rhizomes through container drainage holes or split the sides of plastic pots. Extended holding of container-grown plants increases production costs.
The environmental factors which influence growth of sansevieria are discussed under 3 categories - physical, chemical, and biological.
Physical Factors
Temperature. It is not customary to attempt cold protection of field-grown sansevieria because most fields are not equipped with permanent overhead irrigation systems.
Good growth of sansevieria is observed at temperatures of 70 to 90øF which can be maintained in most greenhouses. Frequently plants grown in central Florida shadehouses are carried with minimal heating through the winter season. Temperatures in these structures should not be permitted to drop 40 to 45øF.
Research has shown that plant nutrition influences the sensitivity of sansevieria to chilling temperatures. Application rates of nitrogen in excess of 50 pounds per acre month markedly increases the level of chilling injury.
Light. Sansevieria receive different light intensities depending upon season and system of culture. Open-field beds in Florida receive full sun which ranges from approximately 8,000 to 14,000 foot-candles at mid-day, depending upon season. Light intensities for finishing acclimatized sansevieria in shadehouses and greenhouses should be between 1000 and 6000 foot-candles. Leaves of plants in heavily shaded areas with only a few hundred foot-candles grow slowly, become elongated, weak, and darker green and without the typical cross-banding pattern.
Water. Most sansevieria beds are irrigated using overhead sprinklers. Approximately 0.75 to 1.5 inches of water is recommended per week for sansevieria stock in open limerock fields depending upon temperature, relative humidity, air movement, and soil type. Less water is required for plants growing under structures, in moisture retentive soils and during cool periods. Growers should reduce watering rates during wet periods to compensate for natural rainfall. Overhead irrigation should be applied early in the day so foliage will dry quickly, thus discouraging development of Fusarium leaf spot.
Tube irrigation for potted plants is recommended for pots over 4 inches in greenhouses because it keeps foliage dry, prevents accumulation of water impurities on leaves, and helps prevent Fusarium leaf spot development.
Chemical Factors
Nutrient Elements and Soil pH. Ten to 12 fertilizer applications per year to stock beds under field conditions or under structures will maintain adequate fertility, plant vigor, and quality. Nitrogen is the most critical element in most nurseries in terms of limiting the rate of plant growth. Stock beds should receive 500 to 750 pounds per acre each of nitrogen (N) and potash (K2O). Phosphorus, expressed as P2O5, should be applied at 300 to 500 pounds per acre per year. The higher rates are most applicable to south Florida due to higher temperatures. Fertilizer rates should be reduced slightly when temperatures below 45øF are anticipated, or when cold water will be dripping on the plants. Media with compounds with little cation exchange capacity, such as perlite, styrofoam, or sand, should have nitrate nitrogen and potassium levels about 20 percent less than indicated in this table.
Potted greenhouse-grown sansevieria should receive the equivalent of 1.7 pounds of actual nitrogen (N), per 1000 square feet per month from a 3-1-2 or 2-1-2 ratio fertilizer.
Sansevieria grow well under a soil pH range of 4.5 to 8.5, although a range of 5.5 to 7.5 is preferred. Stock growing in limerock soils is usually subjected to a pH range of 7.5 to 8.5. The pH of beds prepared in sandy soils amended with peat or potting mixes should be adjusted with dolomitic limestone to a range of 6.0 to 6.8. Dolomitic limestone provides adequate levels of calcium and magnesium.
Soil testing is recommended for nurserymen producing plants in containers of soil mixtures with high proportions of peat, bark, or other components which have a high cation exchange capacity. The total salinity of potting mixes and peat-amended soils of beds or benches should be maintained between 800 and 1500 parts per million (ppm) using the saturated paste soil extraction procedure. Levels exceeding 2500 ppm are excessive enough to reduce plant vigor in some soils. Table 2 shows extractable nitrate nitrogen (NO3-N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) levels for potted sansevieria soils utilizing the saturated paste extraction procedure followed by the University of Florida Soil Testing Laboratory.
Table 2. Suggested ranges of 5 elements in sansevieria potting media z. Concentration of element (ppm)
Element Very Low Low Optimal High Excessive
Nitrate-
nitrogen
(NO3-N) 0-29 30-79 80-159 160-239 240+
Phosphorus (P) 0-3 4-7 8-13 14-19 20+
Potassium (K) 0-49 50-119 120-199 200-279 280+
Calcium (Ca) 0-79 80-199 200-349 350-499 500+
Magnesium (Mg) 0-29 30-69 70-124 125-174 175+
z Soils which contain 30 percent or more of amendments
which have low cation exchange
Leaf tissue tests are also useful for monitoring the nutritional status of sansevieria. Table 3 shows the desirable ranges of essential elements in sansevieria foliage.
Table 3. Suggested range of nutrients for sansevieria foliage. Element Concentration
in foliage
Nitrogen (N) 1.7 - 3.0%
Phosphorus (P) 0.15 - 0.3%
Potassium (K) 2.0 - 3.0%
Calcium (Ca) 1.0 - 1.5%
Magnesium (Mg) 0.3 - 0.6%
Iron (Fe) 50 - 300 ppm
Manganese (Mn) 50 - 300 ppm
Zinc (Zn) 25 - 200 ppm
Boron (B) 10 - 60 ppm
Copper (Cu) 10 - 60 ppm
PHYSIOLOGICAL PROBLEMS
1) Chilling damage
Symptoms -
Leaves are constricted in width in a narrow band across the leaf blade. Usually constricted leaves have normal coloration.
Control -
Maintain production environment at 45øF or above.
2) Severe cold damage
Symptoms -
Cold-injured leaves develop whitish, water-soaked areas 1 to 4 weeks after their exposure to cold.
Control -
Prevent plant exposure to cold air or cold water (condensate or drip through from roof of structure). Low air temperatures account for most of the injury in open stock beds while cold water draining through perforations in polyethylene film used for lining shadehouses accounts for most of the injury to sansevieria in central Florida. Use solid cover structures which are properly heated.
Reference Pest Control Guides Here
WEED PROBLEM
Several weed species are serious pests in field-grown stock beds of sansevieria. The orientation of sansevieria leaves permits plenty of light to penetrate to the soil surface providing little light competition for weeds. At present there are no herbicides labeled for use on sansevieria beds which selectively kill established weeds without damaging the crop.
Research has demonstrated a few preemergence herbicides to be rather effective in sansevieria stock if the beds are thoroughly weeded prior to application of the herbicide. Unfortunately, these herbicides are not labeled for use in sansevieria and cannot be recommended in this publication.
Weeds should not be a problem with greenhouse-grown potted sansevieria, or in greenhouse propagation benches, if soils are properly pasteurized and good sanitation practices are followed. Weeds introduced to clean soil in greenhouses usually come from weeds established inside the structure, airborne seeds entering the ventilation system or other openings in the structures, or, in some cases, seeds carried in water pumped from holding ponds used for crop irrigation.
Reference Pest Control Guides Here
BACTERIAL PROBLEM
1) Soft rot (Erwinia carotovora)
Symptoms -
A mushy soft rot of the lower end of a cutting. Sometimes the plants have a fishy, rotten odor, characteristic of Erwinia infections.
Control -
Bacterial leaf spot can be controlled through elimination of water on leaves. This is almost impossible during rooting of cuttings and preventative applications of streptomycin sulfate (Agri-Strep 21.2%) may aid control. Choice of clean cuttings and strict sanitation are probably the most important control measures. Use of bactericides is not recommended due to very poor efficacy.
Reference Pest Control Guides Here
FUNGAL PROBLEMS
1) Red leaf spot (Fusarium moniliforme)
Symptoms -
Fusarium leaf spot symptoms occur initially on the newest leaves of the plant which are within the central whorl. Infection only occurs when this whorl is wet and spores are present. Lesions are irregularly shaped, sunken, reddish-brown and many times have a chlorotic (yellow) border. Under conditions of high disease pressure and continually wet foliage, the lesions coalesce and infection spreads into the plant meristem. If plants are treated with fungicides and the foliage kept dry, growth in the center may resume, frequently from several buds.
Control -
Keeping the foliage of this plant dry can eliminate the foliar phase of this disease. If this is not possible, use one of several fungicides to diminish symptom expression.
2) Southern blight (Sclerotium rolfsii)
Symptoms -
The pathogen attacks all portions of the plant, but is most commonly found on leaves. Initially, symptoms on leaves are confined to water-soaked, necrotic lesions at or near the soil line. White, relatively coarse mycelium grow in a fan-like pattern and may be seen on the soil surface or leaves. The round sclerotia form almost anywhere on the affected portions of the plant or the soil surface. They are initially white and cottony and approximately the size of a mustard seed. As sclerotia mature, they turn tan and eventually dark brown and harden. Mycelia and sclerotia generally develop concurrently with stem rot and wilting, allowing an accurate diagnosis of the problem. A cutting rot can develop on contaminated plant materials during the summer months.
Control -
Although this disease can be avoided using proper cultural methods, it continues to cause losses in production of foliage plants today. Chemical control of Southern blight has been investigated on several different foliage plants as well as non-ornamental crops.
Reference Pest Control Guides Here
NEMATODE PROBLEM
1) Root knot nematode - (Meloidogyne spp.)
Symptoms -
Galls occur on roots and the root system may be drastically reduced; plant stunting and wilting occur when severe infestations are present.
Control -
Use sterile soil and grow plants off the ground if possible. Dasanit
Reference Pest Control Guides Here
INSECT AND RELATED PROBLEMS
The major arthropod pests of this plant species include moths (worms) and thrips. Moths and thrips have the ability to fly and thus invade the greenhouse from weeds and other infested plants outside. In the control section for each pest, a few of the many registered and effective pesticides will be listed. For a complete listing please consult the references at the end of this report.
1) Caterpillars (worms)
Symptoms -
Infestations are easy to detect because worms, their excrement and the damage they cause, are usually quite visible to the unaided eye. Damage appears as holes in the center or along the edges of leaves. Damage by worms is often confused with slug or snail damage. The only way to determine which pest is involved is to find a specimen. Old damage can be distinguished from new by the calloused appearance of the older damaged areas (worms are usually gone by this time).
Control -
2) Thrips
Symptoms -
Thrips are small (less than 1/20), thin insects. Adult thrips can be identified by a long fringe of hair around the margins of both pairs of wings. Color varies between species with western and other flower thrips being yellow to light brown and banded greenhouse thrips and a few other thrips that feed mainly on leaves being dark brown to black. Feeding takes place with rasping type mouth parts. Infested leaves become curled or distorted, with silver-gray scars or calloused areas where feeding has occurred. Thrips can transmit the tomato spotted wilt virus to many different ornamentals. Any unusual symptoms should be investigated