A Guide for Commercial Production of Vinca (B 1219) University of Georgia Extension Vinca is a specialty ornamental crop with very distinct requirements. This bulletin will address those requirements and cover a typical production schedule and crop budget. 2017-04-19 15:48:55.35 2006-06-02 14:34:00.0 A Guide for Commercial Production of Vinca | Publications | UGA Extension Skip to content

A Guide for Commercial Production of Vinca (B 1219)

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vinca

Paul Thomas1
Jean Woodward2
Forrest Stegelin3
Bodie Pennisi4

Vinca (Catharanthus roseus, Family Apocynaceae) is one of the top-10 best selling bedding plants in the United States. Once established, it blooms all summer. This plant comes in a wide variety of colors and sizes. Vinca is one of Georgia's best bedding plants for hot, dry, sunny locations with sandy loam or Piedmont clay as a principle soil type. It has performed well throughout the state during periods of drought. If consumers are aware of vinca's cultural requirements and provide proper care, it will perform very well in Georgia landscapes. Given an expanded role as a basket or color-bowl crop, the potential for sales of this crop is good.

Unfortunately, many growers shy away from increasing production of this bedding plant because of historically poor cultivar genetics and past failures or mistakes. You cannot grow vinca the same way you grow other bedding plants. Vinca is a specialty crop with very distinct requirements. This bulletin will address those requirements and cover a typical production schedule and crop budget.

Today's new cultivars are more vigorous, predictable and specialized.

Vinca has been bred since the 1920s. Cultivars in commercial production up to the early 1990s had many problems, including very weak stems, poor tolerance of wet weather and susceptibility to many diseases. These older hybrid lines of vinca were bred for flower color, not vigor, and tended to be weak-rooted and much more demanding in their environmental requirements, especially when young. New vinca cultivars on the market are more vigorous, and many of the new series are more specialized to regional growing conditions. Each new series has brought forth new colors to add to the usefulness of this bedding plant.

For example: The 'Victory' series has intense, clear colors and a compact growing habit. The 'Heat-Wave' series and the cultivar 'Santa Fe' are promising and also appear to be more tolerant of warm, dry weather than other cultivars and may be a better selection for southern growers. The series 'Tropicana' and 'Pacifica' perform well in seemingly excessive heat and humidity, and are fast becoming a favorite in the south. The 'Mediterranean' series is another good series that is fairly vigorous and performs well in very warm conditions. 'Morning Mist' is a border type vinca with remarkable tolerance to heat, and 'Parasol' is an All American Selection winner that has excellent branching and heat tolerance. The 'Cooler' series performs exceptionally well under relatively cool, bright greenhouse conditions, making it a well-suited crop in the western United States. Some of the newest lines being evaluated at the University of Georgia include the 'First Kiss' series and the 'Garden Leader Splash' series. Landscapers should welcome the arrival of new colors and improved cultivars.

Vinca 'Parasol' Vinca 'Parasol'

Cultivar selection -- there are differences!

There are three classifications for vinca. Each group defines a growing characteristic that may make its use for a particular basket or pot a good experience or a poor one. Be sure you select the vinca with the desired growth characteristics that match your customer's needs.

Creeping Type Vinca spread rapidly, each plant forming a colorful 8- to 10-inch mat across the landscape bed. They grow slowly and are easily contained. Creeping vincas are good candidates for small hanging baskets and odd-shaped decorative containers (as they can be grown oblong or any odd shape with pinching), and they can be used in elevated planters where cascading flowers are desired. They are very effective as groundcovers in very large outdoor planters if the plants receive full sunlight. An example is the Magic Carpet series.

Dwarf Type Vinca have smaller flowers, form denser plants and have a more upright character than the carpet type. Average height for a dwarf type is 10 to 14 inches. Examples include the 'Little' and 'Cooler' series. They make attractive 10-inch and 12-inch hanging baskets and do not flop over like the larger border types do in baskets. However, they are best used in small patio planters and decorative pots, providing a very neat, upright flower display that does not get too big too fast.

Border Type Vinca have larger 2-inch flowers, are more vigorous and form upright mounds 14 to 20 inches tall. The majority of new cultivars for use in the landscape are classified as border vinca. The 'Heat Wave,' 'Tropicana,' 'Victory' and 'Pacifica' series fall into this category. Some authorities firmly place the 'Cooler' series in the border class, as with warm-weather culture they match the other series in plant and flower size. These plants are well-suited for use in large color bowls, large barrels, city planters and large, main-street baskets 15-36 inches in size.

Commercial Production

Our understanding of the growing requirements for vinca has improved. We now know that the environmental requirements for this species are the most stringent of any commercial bedding plant crop. Vinca is best considered a specialty bedding crop just like fall pansies. Success with this crop requires growers to reevaluate their cultural program and make the necessary greenhouse adjustments. Those who implement the growing program changes will see how trouble-free and profitable this crop can be. The secret to growing and maintaining high quality plants is maintaining an optimal root environment. To accomplish this, you must undertake simple but important changes in your growing program.

Production considerations to evaluate BEFORE ordering seed or plugs

Origins suggest basic culture requirements

Vinca (Catharanthus roseus) originated in Madagascar, a large island off the African coast, and is adapted to hot, dry or windy slopes, bright sunshine, well-drained soil and prolonged summer heat. The soil fertility is poor and, therefore, vinca is adapted to a low fertility environment. Its roots are nutrient scavengers and will not do well under artificially high fertility levels commonly found in most greenhouses. This species requires dry leaves and flowers to stay disease free. Very humid greenhouse conditions, over-watering, overhead landscape irrigation and prolonged rainfall can affect vinca adversely. Sufficient air movement that allows leaves to dry is crucial.

Preparing the greenhouse environment is the first step

Most greenhouses need to be modified to produce high quality vinca crops. Vinca requires higher light level and air movement and they have different watering and fertilization requirements than the average bedding plant, such as marigolds, begonias and impatiens. Bedding plants that grow well under conditions optimal for vinca include salvia, zinnia, melampodium, cosmos and cleome.

Vinca requires long periods of high light levels and warm growing conditions to produce strong roots. In most parts of the country, light levels in January and February are not conducive to growing this species. Supplemental lighting up to a total of 18 hour days, at 1200 to 1500 foot candles (fc), is optimal, but any supplemental light above 200 fc will help. Colder regions of the United States must limit the use of venting so humidity levels are elevated, making the constant use of HAF (Horizontal Air Flow) fans for vinca essential. Twice the number of fans is recommended for this crop than are needed for other bedding plants. There should be a very perceptible air movement across the crop canopy. Vinca are not tolerant of conditions where the soil stays soggy and/or foliage stays wet.

Vinca require warm greenhouse conditions to grow well. Heating the greenhouse to 70 degrees F at night is expensive, but if you wish to grow quality vinca, it is necessary. Bottom heat will greatly improve this crop's seedling growth and accelerate transplant flower production. Installation of in-bench soil warming systems will be a wise investment in northern greenhouses if you consistently have contracts to grow large amounts in January or February. However, a more economic solution is to grow this crop much later in the season. Warmer outdoor temperatures and increased sunlight make production a bit easier. In the south, ordering this crop for transplant in late March and early April is a very sound decision.

These greenhouse modifications cost money. However, the additional cost of a customized house for vinca and other warm-season annuals is offset by reduced losses and on-time production of high quality plants. Doing so for your entire crop of bedding plants does not make sense economically, and mixing impatiens, for example, with vinca never works well. We recommend growing this crop in a specially modified greenhouse where the environment can be maintained efficiently. Most growers involved in the production of large numbers of decorative pots or hanging baskets set aside one Quonset section just for vinca.

Crop production schedules

Because vinca has so many uses, many different schedules can produce a quality crop depending on the container you choose to use. The chart below provides some basic schedules. These are general estimates, as each greenhouse and production program can affect the speed of development.

Table 1. Suggested production schedules for Vinca
Note: The term "North" refers to the northern United States including colder growing regions of the southern Appalachian Mountains; and the term "South" refers to the southern United States, primarily referring to the Piedmont and coastal areas.
Vinca Use Planting Date*** Plants/ Unit Finish Time
Hanging Basket - 12" North: 2/1
South: 3/15
6
5 or 6*
16-18 weeks
7-9 weeks
4" Pot**
Landscape Installation
North: 3/1
South: 2/15
1
1
10-12 weeks
8-10 weeks
4" or 6" Pot
Retail/GC Market
North: 2/15
South: 2/15
3
1 or 3*
14-16 weeks
8-12 weeks
Bedding Flat
Retail Market
North: 2/15
South: 2/15
1
1
12-14 weeks
10 weeks
Color Bowls
(Using 72 plugs or flat material)
North: 3/1
South: 3/15
2/5" space
1/5" space
10 weeks
8 weeks
* Use of vinca at this density allows a 2-week reduction in bench use; this density requires nitrate-based fertility and careful temperature control to avoid stretching.
** Note the delay in production due to later use of crop by professional landscapers. This difference is usually 3-4 weeks later than retail market peak. Also note that plant should be in bloom with 4-5 fully developed flowers.
*** Assumes an April 1 wholesale shipping date for the South, a May 1 wholesale shipping date for the North, a May 15 landscape installation date for the South and a June 1 landscape installation date for the North. Adjust your schedule according to your local market.

When growing vinca from plugs, timing is everything!

Vinca

How early in the spring you order and plant vinca plugs can be a source of poor performance. Trying to plant too soon in the season may cause production delays and poor quality crops. In Georgia, January-planted plugs will take 10 to 15 weeks to be ready for sale, with increased risk of problems depending on the weather. Plugs planted in late March will take only 5 to 8 weeks to grow to proper sale stage due to increased sunshine and temperatures. Local weather conditions strongly influence vinca production. In the north, especially cloudy areas such as those in Pennsylvania and Michigan, it may take 18 to 22 weeks to produce a crop (where supplemental lighting and bottom heating have not been provided). In all cases, keeping night air and soil temperatures above 75 degrees F will yield a rapid crop turnover.

Growers purchasing plugs sometimes complain that vinca is often shipped with little or no root. Professional plug growers have a difficult task. Inspect purchased plugs thoroughly. Accept poorly rooted plugs and you accept all future risk, which will be greatly enhanced by poor root systems. Be selective with vinca plugs and don't order for early delivery. Early plug shipments can easily be chilled to near freezing. Shipping or holding vinca plugs at temperatures of 50 degrees F may cause serious chilling injury. Chilled plugs may recover nicely if allowed to warm up slowly over a day or two without stress. If you suspect chilling, keep plants slightly moist, or "on the dry side," and place them in an area with good air movement and out of bright sunlight.

If receiving plugs, transplant plants within 24 hours for best results. Water the plug trays an hour or two before transplant. Likewise, holding plugs in coolers while catching up with transplanting is not recommended. Be sure your crew makes planting vinca plugs a priority.

Plug size makes a difference

The smaller the plug, the longer it takes to produce a mature crop. This holds true of most bedding plants. With vinca, the larger plug sizes also have an advantage in that the increased amount of root system greatly improves survival and regrowth after transplant. The development of a strong root system after transplant is essential for success. Most growers purchase 512s or 288s for spring bedding production. However, growing small vinca plugs under cool condition in February limits how fast a root system will develop. Put a small 512 plug in a 4-inch pot where the soil is likely to stay wet due to the small root system, and you will increase the chances for disease and root damage due to over-watering. Purchasing larger plugs, such as 144s, provides more root development in relation to the pot it is planted in and reduces the time it takes for roots to grow throughout the new media. Larger plug sizes perform better, grow quicker and are essential for early spring crops started in February.

The Art of Growing from Seed

Growing vinca from seed is difficult and you can experience significant losses from disease. Vinca seed are small, yielding about 28,000 seeds per ounce. However, if you wish to grow vinca from seed, the following is how professionals handle the process.

Stages 1 & 2

Germinate and grow vinca seedlings in the highest porosity peat-lite plug-mix you can get. Maintaining proper moisture levels in smaller soil volumes can be very difficult, so most growers single-seed the crop into plug trays no smaller that 288s. Cover seeds lightly with a medium-grade vermiculite to hold the humidity close to the seed. Seeded trays are usually misted until wet and then placed in a warm, dark room until germination begins. Keep stage one seedlings very moist by frequently misting the trays. Heating mats are often used to maintain soil for the next 6-7 days until radical emerges in most of the seeds. Germination rates of 80 to 90 percent are common under these conditions.

During Stage 2, while the cotyledons are expanding, keep the humidity high and reduce soil temperature to 72 degrees F. You can apply a 50 ppm solution of fertilizer, preferably a nitrate based product such as 15-2-20, at this time. Begin to dry out the soil slightly and never allow the soil to be visibly dry. Keep the soil salt concentration, electrical conductivity (EC), below 0.75 and don't hesitate to leach if you feel salts are building up or if an excessive amount of fertilizer was accidentally applied.

Stages 3 & 4

Between 14 and 21 days, while the true leaves are expanding, it is important to reduce soil temperature slightly again, to 68 degrees F to 72 degrees F for 7 to 10 days, or until most seed has germinated. Supplemental lighting (500-1000 fc) for four additional hours beyond natural daylight hours can speed up development of emerging seedlings during cool, cloudy periods. Leaves usually develop between 7 and 15 days after cotyledon emergence. At this time you may increase the fertilizer rate to 75 ppm. Use high nitrate fertilizers such as 15-2-20 at this stage to prevent stretch. Keep the EC below 1.0. If stretch occurs, you may use a plant growth regulator (PGR) to hold the plugs at this stage (PGR use is discussed under "Height Control."). Allow a total of 5 to 8 weeks for seedling development in the plug tray prior to transplant.

The greenhouse environment you select for "growing-on" the plugs after transplant is also critical. Keep light diffuse and overall levels moderate -- or more specifically, between 2000-2500 fc for plugs. In early season, prolonged cloudy conditions may require supplemental lighting after sunset or before sunrise to maintain adequate growth. Four hours of light at 1500 fc provided via "High Intensity Discharge" (HID) lamps is optimal. However, vinca responds to much lower light levels using incandescent bulbs, etc. Do the best you can to increase the hours of light when growing an early spring crop. Keep the EC below 1.00 mmhos/cm for seedlings at all times. Fertilize using 75 ppm of a high-nitrate, complete fertilizer upon removal of plug trays from the germination environment. Two weeks into transplanted seedling development, increase fertility to 125 ppm.

Vinca plugs do poorly if grown wet, and therefore we recommend "growing them on the dry side of moist." However, new seedlings do not respond well to even a few hours of drought under high light intensities. This is especially true of 2-week-old seedlings. Since we are recommending growing on the dry side of moist, there is very little room for error. It is critical that you monitor plug moisture hourly. The medium should never be dry. Even at 75 ppm, fertilizer salts concentrate and can cause root damage. It is a fact that vinca roots are slow to grow and seedlings almost never recover from severe soil moisture stress. One afternoon of slight stress under high light levels will delay a vinca seedling's growth 1 to 2 weeks. Hourly scouting is essential.

Transplant Carefully

Irregular growth 
      due to poor handling Irregular growth due to poor handling

Many bedding plants are tolerant of rough treatment during transplanting and will grow out of root ball abuse. Vinca, however, is not one of them. A very common problem is irregular growth in a flat due to rough handling. Manual transplanting by crews unaware of the fragile nature of vinca's roots is the most common cause.

If your vinca is growing very irregularly, inspect the transplanted plug. If it has a "J" hook appearance, where the plug was smashed on one side, with dead root tips and/or no root hairs a week after transplant, your crew has likely improperly handled the plug, pushing it in sideways and/or forcing it down into the soil with their thumbs. Once damaged, the roots rarely regain vigor and potential disease penetration is increased. Vinca is ideally suited for automatic transplantation. If you can't automate, you must educate! Have your staff dibble a small hole in the soil first and then set the plug in gently. Vinca transplanting cannot be rushed.

Be watchful of the soil depth of plugs at transplanting. Exposed plug root balls act like wicks and draw water and salts, which can accumulate and desiccate the roots. Scouting your new transplants for shallow planting or planting too deeply can prevent a major problem from occurring later.

Avoid Substrate Charge in the Soil Substrate

Vinca does poorly if soil solution fertility levels are higher than 1.0 mmhos. High soluble salts inhibit root growth. Remember, root growth is the key to top quality vinca. Transplanting immediately into warm soils with a high level of substrate charge (fertilizer added by the manufacturer) on a sunny day doubles the stress on the roots. Like-wise, transplanting plants into a soil with high substrate charge and then maintaining them under cool, wet conditions will also cause loss of roots. It is best to begin by using a low- or no-charge soil. Your soil manufacturer can tell you whether or not the soil has a fertilizer charge in it. If you cannot determine if this is the case, a soil test through your local Cooperative Extension Service will identify if fertilizers are present. Test first when in doubt! If you use a charged soil, leach at transplant. This is accomplished by gently watering every 20 minutes for three cycles to flush out the excess fertilizer. Once the plugs' roots begin growing vigorously, you can fertilize with 50 ppm of a 15-2-20 high-nitrate fertilizer for two weeks. After a few new leaves have expanded, the rate can be increased to 125 ppm.

Type of Nitrogen Affects Plant Quality

Researchers have documented that vinca do not like elevated levels of ammoniacal nitrogen (>25 ppm) or phosphorus (>20 ppm) in the soil. In the south, especially, long term (4- to 6-week) exposure to ammoniacal nitrogen concentrations as low as 50 ppm can strongly inhibit vinca root growth in established plants and will promote stem stretch under warm, moist soil conditions. Know your fertilizer product and how it interacts with your soil. Ammoniacal nitrogen or slow-release urea used in some commercially prepared soil mixes can impart levels as high as 200 ppm NH4+.

There is also strong evidence that phosphorus plays an important role in how fertilizers affect plant growth. Using fertilizers low in phosphorus has been shown to reduce the incidence of stem stretch when plants are grown in warm weather. Not coincidently, most nitrate-based fertilizers designed for vinca are also low in phosphorus.

Suggested Fertility Program

Root burn from 
      excess slow release fertilizer Root burn from excess slow release fertilizer.

When establishing new plugs in a new soil, irrigate with a solution of 50 ppm 20-20-20. The high ammonia content will reduce the time the seedling needs to recover and take hold onto the new container. However, cease ammoniacal fertilization once the seedling root system begins to grow and hold the new soil. For the remainder of the production cycle, use fertilizers such as 15-2-20, or a rotation of one application of 125 ppm "20-10-20 with trace elements" for every two applications of 100 ppm calcium nitrate.

Table 2. Suggested fertility programs for Vinca grown in soil-less medium
Fertilizer Type Rate
(in ppm)
Frequency
20-10-20* - Pulse 100 Once a week - cool weather
Twice a week - warm weather
20-10-20* - Continuous 65  
15-2-20* - Pulse 125 Once a week - cool weather
Twice a week - warm weather
15-2-20* - Continuous 100  
Calcium Nitrate - Pulse 100 Every third fertilization
* This program assumes that these products contain a balanced trace element component.
Each graph represents 
      plants grown with 100 parts per million (ppm) total nitrogen. The percentage 
      of nitrate increases in relation to ammonium as you read from the right. 
      For example, the treatment designated as 50 is a 50/50 mixture of NO<sub>3</sub> and 
      NH<sub>4</sub>. Each graph represents plants grown with 100 parts per million (ppm) total nitrogen. The percentage of nitrate increases in relation to ammonium as you read from the right. For example, the treatment designated as 50 is a 50/50 mixture of NO3 and NH4.
Each graph represents 
      plants grown with 100 parts per million (ppm) total nitrogen. The percentage 
      of nitrate increases in relation to ammonium as you read from the right. 
      For example, the treatment designated as 50 is a 50/50 mixture of NO<sub>3</sub> and 
      NH<sub>4</sub>.

Nutrient Deficiencies

Vinca is very susceptible to iron deficiencies as well as low nitrogen levels. It is also very sensitive to nutrient toxicities and general over-fertilization. Learning to recognize these symptoms will help manage production problems before they become serious and delay the crop. Recent research at North Carolina State University (Campbell, et. al. 2001) has clearly defined the deficiency symptoms listed below. Images are available on the NC State website:

http://www.ces.ncsu.edu/depts/hort/floriculture/crop/crop_bp.htm

Nitrogen:

Nitrogen deficiencies are surprisingly common. Vinca express nitrogen deficiencies through a gradual yellowing of the leaves. This yellowing pattern is very distinct, with very strong veinal chlorosis; specifically, the veins turn bright yellow and the leaf space between the leaves remains green. Eventually the entire leaf turns yellow. Crop delays due to nitrogen deficiencies can be significant.

Potassium:

Potassium deficiencies are very rare and are manifested as curling down of lower leaf tips, so the leaves resemble an umbrella. Necrotic spots can develop on the leaves between the veins if the deficiency is severe.

Phosphorus:

Phosphorus deficiencies also are rare and may not be easily diagnosed visually. The early stages of deficiency are expressed as a leaf darkening or a development of a deep green cast. The most severe symptom is a slight yellowing of the entire plant with concurrent leaf droop. A purplish or bluish tinge along the leaf interior is visible in some cases.

Magnesium:

Magnesium deficiencies are common and easily recognized by a chlorosis beginning at the lower leaves, then spreading upward on the plant. Within the leaf, the chlorosis spreads from the outer edges inward to the mid vein.

Calcium:

Calcium deficiencies are first characterized by the younger leaves turning somewhat glossy, followed by the new leaves. Developing leaves become distorted. Newly maturing leaves may become strap-like and cup downward. Leaves may eventually become necrotic.

Iron:

This is the most common deficiency in vinca. Iron deficiency is expressed as a slowly progressing yellowing of the new leaves, spreading rapidly to the entire plant. Often root damage is expressed as an iron deficiency as the plant shuts down. The plants will turn almost yellow if not treated. Check pH, root integrity and your spray records, and get a soil test done before applying iron supplements. Vinca are very sensitive to iron toxicity as well. Be especially careful when using chelated iron sources that have iron-DPTA or iron-EDTA. These chelated sources should be kept below 5 ppm at all times to avoid root stunting. Iron-EDDHA seems not to cause the same root stunting problems. Apply to the product label to determine the form of chelating agent. Application of 1 ppm of iron-EDTA is recommended for vinca that show iron deficiency symptoms.

Copper:

Copper deficiencies are rare and easily corrected. Copper deficiencies are expressed as an overall growth stunting, with new leaves turning darker green and becoming slightly distorted. Severe or pr

Status and Revision History
Published on Mar 3, 2006
Re-published on Feb 27, 2009
Reviewed on Feb 14, 2012
Reviewed on Feb 1, 2016