Commercial Greenhouse Production
Scientific Name: Viola × wittrockiana
Common Name: Pansy, Viola
Dr. J. Raymond Kessler, Jr.
Pansies have emerged as one of the most popular bedding plants for cool seasons of the year and have become popular in milder climates for fall planting. In the past 8-10 years, sales in the southeast have increased tremendously making pansies a major off-season sales item. Many pansy cultivars will withstand temperatures down to 2-5F and continue to flower through light snow. In the south, pansies are marketed throught retail outlets starting late September, with peak sales in October, and extending into November. Customers may expect color in the landscape for as long as six months from fall, through winter, and into late spring. No other annual or perennial plants provides lasting color during this period of the year.
The breeding of pansies include several species, though Viola tricolor is the major parent. Violas, called 'Jonny Jump-ups', are smaller plants with smaller flowers that are becoming more popular and have Viola cornuta as the dominant species. The origin of modern pansies began in England in 1815, and by 1850, many cultivars were available to European gardeners. True F1 hybrids appeared in the late 1950s and 1960s. Recent breeding efforts have concentrated on quality issues such as plant vigor, heat tolerance, and free flowering. Pansies are divided into two groups based on flower color: 'clear' types have flowers in one solid color while 'faced' flowers are multicolored. There are three main categories based on flower size: 1) Large - 3½-4½" diameter blooms, 2) Medium - 2½-3½ diameter blooms, and 3) 1½-2½ diameter blooms. There are over 300 cultivars available today, most contained in series. Generally, cultivars within a series share similar plant characteristics such as plant size and heat tolerance, but have different flower colors and, sometimes, different color patterns. Pansy cultivars come in a wide range of colors including red, purple, blue, apricot, orange, lavender, white, yellow, pink, bronze, black, and mahogany.
Grow versus Purchase Plugs
Pansy producers must decide whether to purchase plugs or grow their own from seed. Growing plugs requires a major investment. The decision should be based partially on market considerations, labor availability and expertise, the number of plants to be produced, the costs per plug, and the specialized equipment and facilities required. This investment is often not economically practical unless production is large or plugs are marketed to other growers. For most small to medium sized growers, especially those just starting to grow pansies, it is often more economical to purchase pansy plugs from specialized growers and concentrate on producing finished containers. The issue of grow versus purchase should be reviewed periodically as the needs and facilities of the grower changes.
Refined seed and primed seed are available from several seed companies. The main advantage to primed seed include higher percent germination, faster germination, and less sensitivity to high temperatures. However, primed seed costs more than refined seed. Pansy seed germination needs to occur in July and August in the southeast for fall sales, months not conducive to optimum seed germination and early seedling growth. Therefore, germination chambers with efficient cooling systems are almost imperative. Many small to medium size greenhouse operations find it more feasible to purchase plugs for the early fall markets. However, growing plugs for later season crops is much easier due to cooler temperatures.
Pansy seedlings are most often grown in 288 or 392 plug flats. Sowing to ready to trasnsplant usually requires about 6 weeks in 288 flats or 5 weeks in 392 plug flats. The germination medium for pansy seed should be fine textured, well aerated, and well drained with a pH of 5.5-5.8. Avoid media with much nutrient charge because pansy seedlings are especially sensitive to soluble salts (<0.75 mmhos/cm). A medium with dolomitic lime for pH adjustment, micronutrients, and a small amount or no superphosphate with no nutrient charge is ideal. High phosphate causes seedlings to stretch. Pansy seedlings are also sensitive to high ammonium (<10 ppm).
Temperatures in stage 1 should be 68F for the first 3-7 days, then 62-68F in stage 2. Temperatures above 75F inhibit germination. Lower temperature to 60-62F in stages 3 and 4. Light is not required for germination and a light seed covering of course vermiculite is often used to retain moisture around the seed. High humidity without saturating the medium is needed for germination, but reduce moisture levels once the radicle emerges. Begin fertilizing with 50 ppm N from calcium/potassium nitrate as soon as cotyledons emerge. Apply a protective fungicide for Thielaviopsis and Pythium as soon as a stand is established.
For fall pansy production, being prepared to focus on production tasks when plugs for the first few crops arrive is one key to a successful season. Often, the first few transplantings are done during a period (the hottest weather) when the crop is least forgiving of mistakes.
If plugs are purchased, unpack and examine the plug carefully. Are the plants a correct size for transplanting? Overgrown plugs are difficult to make into a quality plant, while seedling that are too small will be difficult to transplant and slow to establish. Remove several seedlings from sample flats and examine the root system. Look for signs of overwatering and root rot diseases. Examine the foliage for diseases, insects, or nutrient deficiencies. Be prepared to transplant plugs immediately. Plugs are usually shipped at a size that is ready to transplant. Holding plugs in the greenhouse will only decease quality.
Temperature: Correct temperature is the most critical aspect for growing-on and finishing pansies. Cool temperatures are essential. After transplanting, night temperatures should be 55-60F and day temperatures 62-68F. Higher temperatures result in tall, poorly branched plants. For fall panies, high temperatures during the early crops can exasperate nutritional problems and increase stretching. These problems usually lessen when night temperatures drop below 62F.
Photoperiod: Photoperiod control is not practiced for pansy.
Light: Generally high light plants. Shading, at 20-40%, is practiced early in the fall production season only to control temperature. Many growers provide some shade in the first week or ten days to help get plugs established.
Growing medium: Light, well-drained, peat-lite medium with a pH of 5.5-5.8 with an EC less then 1.0 mmhos/cm. A pH above 6.5 causes boron and iron deficiency.
Watering: Pansies should be allowed to dry between watering, but never allowed to wilt. Do not overwater. Prolonged saturated medium will delay rooting and lead to nutrient imbalances.
Fertilization: In the medium contains a small nutrient change, delay the first fertilization for a week or 10 days. Thereafter, fertilize at 100-150 ppm N CLF using a fertilizer low in phosphate and ammonium or calcium/potassium nitrate. Use the lower rate where leaching is minimal, and the higher rate under higher leaching. A weekly program using 225-275 ppm N can be used, but CLF is prefered. Rotating between a basic-residue fertilizer such as 13-2-13-6Ca-3Mg and an acid-residue fertilizer containing phosphorus such as 20-10-20 assures an adequate supply of macronutrients while maintaining pH (see table). Soluble salts should be around 1.0 mmhos/cm. Magnesium deficiency can be a problem. Apply magnesium sulfate at 8 oz. / 100 gal. once per month.
|Pansy Tissue Analysis Normal Ranges|
|N||3.5 to 4.5|
|P||0.3 to 1.0|
|K||3.0 to 4.5|
|Ca||0.6 to 1.2|
|Mg||0.3 to 0.6|
|S||0.3 to 0.7|
|Na||0.1 to 0.4|
|Fe||100 to 300|
|Mn||100 to 300|
|Zn||35 to 100|
|Cu||5 to 15|
|B||20 to 50|
The following table outline PGRs used on pansy and during which production stage. Final solutions of these chamical should be applied at ½ gallon per 100 sq.ft. of growing area. This rate should result in wetting the foliage without run-off. Generally, do not apply PGRs until visible growth has begun after transplant. Avoid late applications that may delay flowering and slow growth in the landscape.
|B-Nine||seedling||2500 ppm||Weekly application after first true leaf is present, as needed.|
|Bonzi||seedling||1-5 ppm||3 ppm when 2 true leaves present or 1 ppm multiple sprays.|
|Bonzi||flats||5-15 ppm||Apply when plants 2" diameter, higher rate in warm weather.|
|Sumagic||seedling||1-3 ppm||3 ppm when 3 true leaves present, 1 ppm multiple sprays.|
|Sumagic||flats||3-6 ppm||Apply when plants 2" diameter, higher rate in warm weather.|
Supplemental Carbon Dioxide: Supplemental carbon dioxide also improves growth at 1000 ppm. Apply beginning stage 2 for 3-5 weeks.
Scheduling: The time required form sowing to ready to transplant is 5-7 weeks. Flats ususally require 3-6 weeks from transplant to ready to ship depending on time of year, container sizes, and marketing specifications. Total production time is 8-13 weeks. Count back from the projected market date to determine when plugs should be transplanted.
Physiological: Warm temperatures result in plant stress, causing a greater incidence of disease and internode elongation.
Pests: Spider mites, aphids, and thrips.
Thielaviopsis (Black Root Rot): This disease appears as yellow lower foliage, stunting, and overall reduced vigor. Affected roots will show blackened lesions and overall deterioration. Generally, panies are more susceptible when placed under stress. Heat stress can often be the culprit in early fall crops. Some of the best ways to prevent this problem is to always use new growing containers, sanitation, and maintain the proper pH. Black root rot is favored by high pH so maintain the pH at 5.4-5.8. Cleary's 3336 50W at 12 oz per 100 gal or Terraguard 50W at 8 oz per 100 gal may be used as a drench control.
Pythium and Phytophthora: All are more prevalent under heat stress and overwatering. Low soluble salts, proper pH management, and good air circulation helps to reduce disease incidence.
Cercospora Leaf Spot: Produces a black leaf-spot that is worse on the lower foliage. Lower foliage turns yellow and falls off.
Nutritional: magnesium, iron, and boron deficiencies. These are often pH related.
|Acid- and bacic-residue fertilizers (oz/100 gal)|
|Fertilizer||Concentration N and K2O|
|Acid-residue||50 ppm||75 ppm||100 ppm||250 ppm|
|(20-10-20) ammonium nitrate||1.23||1.85||2.5||6.15|
|+ potassium nitrate||1.50||2.25||3.0||7.5|
|+ monoammonium phosphate||0.54||0.81||1.1||2.7|
|+ calcium nitrate||1.76||2.64||3.52||8.8|
|+ magnesium nitrate||1.80||2.7||3.6||9.0|