History
Potting Media
Boron Deficiency
Scheduling
Scope of Production
Potting
Light Intensity
Disbudding
Cultivars
Disease Prevention
Supplemental Light
Cultural Problems
Propagation
Watering
Temperature
Insect Problems
Purchased Seedlings
Fertilization
Growth Retardant
Disease Problems

 

History
     The species from which Florists Gloxinias were derived came from Brazil in 1785. The name Gloxinia speciosa was originally assigned in 1817 by Conrad Loddiges, an English Nurseryman, in honor of P.B. Gloxin of Strasburg, Germany. In 1825, the species was renamed, placing it in the correct genus, Sinningia. The modern Gloxinia is a hybrid from two Brazilian tropical species; Sinningia speciosa and Sinningia maxima. It arose as a chance seedling raised by a Scottish gardener, John Fyfiana, in the nineteenth century.

Scope of Production
     Most growers produce Gloxinias on a small scale. Producers usually obtain established seedlings from specialized propagators (Earl J. Small Growers, Inc.) for either year round production or, more often, to meet holiday demands. The primary holidays are Mother’s Day and Valentine's Day.

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Cultivars
     Gloxinia flowers may be single or double and come in a variety of colors from pure white to pink, lavender, red, or dark purple. Bicolors and those with petals edged in white are very popular. However, the velvet red and purple outsells all others. Hybridization and selection has resulted in three cultivar size groups; the large-growing, standard types are grown for 5- to 6-inch pots, the compact types are grown in 4½- to 5-inch pots, and the miniature types (minis) are grown in 4-inch pots. Mini types come in two flower types, tubular shaped flowers which sell the best and slipper shaped flowers. Mini types generally have fewer production problems and ship better than the other two sizes. They have more flexible foliage and can be sleeved which is difficult with the other two sizes. All size types of Gloxinia seedlings require basically the same cultural procedure with the exception of crop timing and pot size.

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Propagation
     Many growers today purchase established seedlings of high quality cultivars from specialized propagators. However, excellent cultivars are available for the grower to produce from seed. Gloxinia seed are very small (800,000 seed per ounce). Therefore, seed should be sow in open flats (often wooden flats that are steam sterilized between use) using a fine (often screened), sterile, peat-lite medium that is 1½ to 2 inches deep. A layer of course vermiculite is often added on top of the germinating media to hold moisture. Gloxinia seed may be mixed with sand and shaken thinly onto the vermiculite surface. Do not cover the seed. Germinate the seed using frequent light watering (no mist) and with a 70-75°F soil temperature. The light intensity during germination should be no more than 2,000 foot-candles. Germination should occur in 2 to 3 weeks. Begin fertilizing seed flats a week after germination at a rate of 150-200 ppm nitrogen applied one out of every three irrigations. Use a low or no ammonium fertilizer such as 17-5-17. A one time application of 20-10-20 may be used to green the seedlings up if needed. Rinse the foliage with clear water after fertilizing.
Once seedlings are large enough to handle in germination flats, transplant them to 50 to 200 cell flats. Seedlings flats are often picked out several times to select seedlings of uniform size for transplanting into cell flats. Drench the cell flats with Banrot, Subdue or Truban to prevent diseases. B-Nine can be applied as needed at 700 to 900 ppm to keep the seedlings compact. Avid and Sanmite can be used on seeding to control thrips that may damage the young foliage and growing point. Marathon can be used to control white flies and Nemasys can be used to control fungus gnats. Seedlings are transplanted into the final containers when leaves begin to touch in the cell flats. Gloxinias may also be propagated from tubers or leaf cuttings but these methods are rarely used commercially.

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Purchased Seedlings
     Unpack the seedlings and examine them closely for potential problems such as insects, diseases or shipping damage. Contact the propagator promptly if problems are found. Place the seedlings in a greenhouse and water them as needed. Allow the plants to acclimate for a few days. It is not necessary to transplant the seedlings upon arrival but they should be transplanted after no longer than five days. Seedlings left in a small containers too long can be stunted and will prematurely set flower buds resulting in poor quality plants.

     Earl J. Small Growers, Inc. provides standard and compact type Gloxinia seedling in 50, 72, or 105 cell flats, the mini type seedling also come in 200 cell flats. Which size a grower chooses to purchase depends the cost per seedling verses the amount of time the grower has to finish the crop.

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Potting Media
     In general, Gloxinias require a light, well-drained potting media high in organic matter. To mix your own, start with 50-60% peat and add perlite, vermiculite, course sand, aged bark or calcine clay for good drainage. The media should be amended with dolomitic limestone to a pH of 5.8 to 6.5. Superphosphate and micronutrients may also be incorporated at a reduced rate. Many commercially available peat-lite mixes have also been used successfully.

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Potting
     Gloxinias may be grown in 4-, 4½-, 5- or 6-inch pots depending on the cultivar size group and the size finished plant desired. Within a size group, a larger pot will produce a larger plant and a smaller pot will produce a smaller plant. Before removing the seedlings from a cell flat, hold the flat at each end and flex the center of the flat upward to loosen the soil balls from the cell interiors. This help prevent damaging the seedlings when they are removed from the flats. Fill the pots loosely with potting media and form a hole in the center so the seedlings can be inserted deep enough that only ¼- to ½-inch of the crown and two pairs of leaves are above the soil line. To do this, it may be necessary to bury the lower set of small leaves. Do not intentionally break or remove the lower leaves because this encourages disease problems. Tall seedlings that may have stretched will finish fine when planted this way. Do not pack the soil because poor media aeration results in poor root development and stunted foliage. The newly potted plants can be held pot-to-pot for the first four weeks, then placed at a final spacing when leaves of adjacent plants begin to touch. It is critical to space plants on time. If leaves on adjacent plants begin to push each other upward, crop quality may be reduced. Space the mini types in 4 or 4½ inch pots 9 to 10 inches on center, plants in 5-inch pots 10 to 12 inches on center, and plants in 6-inch pots 12 to 14 inches on center.

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Disease Prevention
     Always apply a fungicide drench after potting to guard against diseases. Use Cleary's WP plus Subdue 2E, Cleary WP plus Truban, or Banrot. A second application of fungicide may be applied six weeks after the first application for complete disease control that will last the entire production period. A light foliar rinse with clear water should be applied after the fungicide drench to eliminate possible injury to foliage and residue.

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Watering
     Gloxinias thrive best when the soil is maintained uniformly moist. However, they should not remain wet for long periods in winter. Plants in small pots should never dry out to the wilting point. If they do, flower buds may set prematurely and the plants will flower before reaching the desired size. Gloxinias can be watered overhead with a hose and water breaker, especially in the early stages, as long as the water is tempered and the greenhouse is not too hot and bright. In all seasons it is a good practice to water early in the morning so the foliage drys quickly. It is very importance that the water temperature be close to the air temperature when overhead irrigating. If the water is too cold (below 50°F), bleached rings may appear on the leaves called 'ring spot' and roots may be damaged. Many growers temper their water with large water heaters or heat exchangers associated with the boiler heating system. At the final spacing, many growers use microtubes, capillary mats, or ebb-and-flow watering systems to avoid water contacting the foliage and flowers and to provide greater watering uniformity.

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Fertilization
     Begin fertilizing seedlings transplanted to the final containers about 10 to 14 days after potting. Alternate 17-5-17 and 20-10-20 in the warmer months and 17-5-17 alone in the cooler months at 200-250 ppm nitrogen. Apply fertilizer one out of every three irrigations. Use the lower rate in the winter and the higher rate in the summer. Plants on sub-irrigation systems can be fertilized at 125 ppm nitrogen. Slow-release fertilizers, such as Osmocote 14-14-14, can be used at one-fourth the recommended rate. However, avoid 20-20-20 or any fertilizer with over 40% of the total nitrogen in the ammonium form because these have resulted in foliar disorders. Twisted, cupped, or curled leaves with a general deep blue-green color are often symptoms of excess fertilization or high nitrogen. These symptoms can occur in the winter when plants require water less frequently and less leaching takes place. The recommended electrical conductivity standards for Gloxinias are 0.76-2.0 mmhos/cm for the saturated media extract method, 0.7-1.0 mmhos/cm for the 2:1 method, and 1.0-2.6 mmhos/cm for the pour-through method.

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Boron Deficiency
     Watch for boron deficiency during periods of high light in the summer. This problem usually appears before the plants get large and may be confused with chewing insect damage. Crown leaves will be deformed and appear eaten around the edges. If the leaves have holes or slits, the problem is not boron deficiency but more likely insects such as thrips. Boron deficiency usually occurs in soil-less media with little or no micronutrients The problem is easily solved using a spray of Borax at ½ ounce per 1000 gallons, or one gram per 75 gallons.

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Light Intensity
     Light intensity for seedlings and cell flats should be kept low, about 2000 foot-candles measured at noon on a clear day. Removable shade cloth can be used inside the greenhouse for this stage. Finish plants should receive 2000-3000 foot-candles depending on the time of year. During the winter season, higher light intensities can be used when temperatures are more controllable and the number of hours of natural light are short. In the summer, lower light intensities are best to help control heat. Many growers in northern parts of the U.S. can get by with full sun in the winter months. If plants start to stretch, remove some of the shade. If the foliage appears yellow or mottled, growth is hard, or small gray-brown spots appear on the leaves, add more shade.

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Supplemental Light
     Dark, overcast weather in the winter can delay Gloxinia growth. Supplemental light from high intensity discharge lamps (metal halide or high-pressure sodium) can be used to supplement ambient sunlight and speed progress of the crop by several weeks in the winter. The lamps should supply about 200 foot-candles at bench level and be turned on for 14 to 16 hours per day (6:00 AM to 10:00 PM). Supplemental light is more economical if applied to cell flats or during the four weeks plants spend pot-to-pot because fewer lamps will be required to light the crop compared to after they are spaced out. Young plants also respond more to supplemental light than older plants. Supplemental light is very useful for standard and compact Gloxinias, especially in Northern climates.

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Temperature
     For best growth, the night temperature should be 65-68°F and 75°F during the day in the winter. Progress of the crops can be speeded up or slowed down be increasing or decreasing the night temperature. Do not exceed 85°F during the day in the summer. Low day or night temperatures in the winter can delay Gloxinia growth. Careful attention should be paid to proper ventilation and reducing relative humidity during the winter to reduce condensation and prevent diseases. Conversely, high relative humidity is important during the hot, dry weather in the summer. At this time, paths can be wet down to raise the humidity.

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Growth Retardant
     B-Nine can be applied as a spray at 1250 ppm, 7 to 10 days after potting or when the first set of leaves reaches the pot edge, to prevent main stem and petioles from stretching. A second application can be applied 7 to 10 days later if needed to the standard types under low light conditions. Under proper cultural conditions, i.e. light levels and watering practices, a second application is often not necessary. One application or no growth retardant may be needed for the compact types. Do not apply B-Nine to mini types.

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Scheduling
     The schedule shown in figure 1 is a generalization and individual stages may require a week less than indicated or a week more depending on the time of the year and geographic location. Starting from seed, large-growing types require 20 to 27 weeks. Seed can be sown in August for Valentine's Day sales and in November for Mother’s Day sales. The compact types generally require 4-8 weeks less time than the standard Gloxinia. The following is a general production schedule for standard Gloxinias:


For growers who order seedlings from propagators, time to finish is about 10 to 14 weeks for the large-growing types, six to 10 weeks for the compact types, and seven to 10 weeks for the mini Gloxinias (Table 1). The variation in time to finish in different seasons reflects changes in light levels and temperatures.

Table 1. Production time for standard Gloxinias in 6-inch pots.
Weeks to finish from:
Winter
Spring
Summer
Fall
2¼-inch Liner
13 - 14
12
10
11 - 12
1½-inch Liner
13½-14½
12.5
10.5
11½ - 12½
Production time for compact Gloxinias in 4½-inch pots:
Weeks to finish from:
Winter
Spring
Summer
Fall
2¼-inch Liner
9 - 10
8
6 - 7
7 - 8
1½-inch Liner
9½ - 10½
6½ - 7½
7½ - 8½
Production time for mini Gloxinias in 4-inch pots.
Weeks to finish from:
Winter
Spring
Summer
Fall
200 plug
9 - 10
8 - 9
7 - 8
8 - 9

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Disbudding
     Growers often remove the first pair of dominant flower stalks that arise from the canopy before they show color. A few of the uppermost leaves may also be removed if the center is congested to open the remaining flower buds to light. This results in a flush of six to eight flowers opening at one time and a very showy Gloxinia product. The image above shows the correct developmental stage for disbudding.

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Cultural Problems
• Premature flower buds may be caused by leaving plants in cell flats too long, excess heat or light, lack of nitrogen, or allowing very small plants to dry out too much before potting.
• Twisted, curled or cupped leaves are caused by some type of fertilizer toxicity such as high ammonia in winter, or even by cold drafts.
• Deep blue-green foliage that may appear stunted is caused by excess fertilizer. Excess B-9 also produces the same symptoms.
• Flowers hidden under foliage or plants remaining in a vegetative state without flowers are usually caused by excess fertilizer, high ammonia or too low day and/or night temperature.
• Yellowing of leaves with lighter yellow areas between veins are caused by excessive sunlight and/or high ammonia type fertilizers, or by a combination of high light and too little nitrogen or root loss due to high soluble salts or over-watering.

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Insect Problems
     Caterpillars, cyclamen mites, foliar nematodes, spider mites, and thrips can be problems on Gloxinias. However, thrips are the most difficult.

Caterpillars can chews the leaves of Gloxinias and are most likely to be a problem in summer or fall. Apply Dipel, Conserve or any of the pyrethroid insecticides labeled for caterpillars.
Cyclamen mites are too small to be seen without a magnifier, but may be detected by the stiffening and discolored reddish-brown young leaves. Use Talstar for light infestations and Pylon for heavy infestations.
Foliar Nematodes cause small tan, sunken areas to form on leaf tips and margins. Spots become dry and dull black. Destroy infected plants. Water plants in a manner that keeps leaf surfaces dry and does not splash water from plant to plant.
Broad mites and 2-spotted spider mites occur mostly on the underside of leaves and their feeding causes a mottled or speckled appearance on the upper leaf surface. Spider mites can develop quickly under warm, dry conditions. Apply Talstar.
Thrips can attack the growing tips of small plants and cause the leaves to grow out deformed with cuts, holes, or ragged edges. Develop a spray rotation of several different insecticides with different modes of action. Good success has been achieved with BotaniGard or Naturalis to plants without flowers. Conserve and Mesurol can be used if populations are high. Thrips feeding on flowers is a difficult problem because the delicate open blooms of Gloxinias are very subject to damage be many insecticides. Avid and Sanmite can be applied to flowers open.

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Disease Problems
     Botrytis blight, Myrothecium, Phytophthora, Pythium, and viruses can infect Gloxinias. Greenhouse sanitation procedures can go a long way toward preventing these problems.

Botrytis Blight causes small water-soaked lesions that form on damaged petioles and spread to leaf blades. Infected flowers fade prematurely. Space plants and provide ventilation to avoid high humidity. Remove fading flowers and yellowing leaves. Apply Decree or Compass. Do not use Chipco 26019 or Cleary because they leave an unsightly residue on the foliage.
Myrothecium causes petioles of lower leaves to develop darkened spots. The spots enlarge down the stems and stems are easily broken. Plant in clean media and do not reuse containers. Apply Chipco 26019 to leaves and stems. Maintain moderate temperatures and low humidity.
Phytophthora crown rot causes roots to have a dark, water-soaked appearance. This spreads to petioles and leaf blades. Young plants are often quickly killed. Pot in clean media and destroy infected plants as soon as they show symptoms. Apply Banol, Banrot, Subdue 2E, Subdue MAXX, Terrazole, or Truban to protect healthy plants.
Pythium root rot causes dark brown roots. Plants wilt, yellow and die. Pot in clean media and destroy infected plants as soon as they show symptoms. Apply Banol, Banrot, Subdue 2E, Terrazole, or Truban to protect healthy plants.
Virus infection symptoms vary. Leaves may have dark brown to black dead areas in line patterns. Flower petals may be spotted. Leaves may be downwardly cupped, mottled, or narrowly shaped. Leaves may have line or ring spot patterns. Shoots may be elongated. Impatiens necrotic spot virus, tobacco mosaic, tomato spotted wilt or tomato ring spot virus can be problems on Gloxinias. However, Impatiens necrotic spot is probably the most serious and wide-spread. Maintain good thrips control including screen them out with fine-mesh screen. Destroy infected plants. Eliminate weeds within the production area and within 30 feet outside the greenhouse. Do not use tobacco products when handling plants. Keep Gloxinias away from other crops known to be susceptible to Impatiens necrotic spot virus.

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