Viola Endurio Series By Heidi Doering

The unique, mounding, spreading habit makes Endurio a versatile and profitable cool-season crop for growers, retailers, landscapers and home gardeners. Endurio viola is perfectly designed for autumn, winter and spring basket and patio container production. They mix well with other plants to create striking combination planters and landscape plantings.

Endurio viola is bred by Martien Gutter of Syngenta Flowers (breeder of Delta pansies, one of the most recognized names in pansies, as well as the heat-tolerant Colossus pansies). Endurio was introduced to the U.S. market in 2006 and features innovation in breeding that gives growers reason to rethink cool-season container programs.

Variety Information

Endurio varieties feature a semi-trailing habit that sets them apart from other violas in the marketplace. Where the Alpine viola series has been a dependable choice for landscapers for many years, Endurio violas are more versatile and adaptable to hanging basket and mixed combination planter production as well as landscape use and should generate impulse sales at retail. The habit of Endurio is more mounding than Alpine, bringing it up off the ground 4-6 inches while maintaining extreme weather tolerance similar to Alpine. Endurio violas also feature more lateral branching than other upright violas for faster fill in pots, a tidier appearance when featured in baskets or bowls, and more colorful coverage of flowers over the top of the plant.

In addition to Endurio's unique habit, our breeders have also removed the day-length sensitivity response to make summer/autumn long-day production easier and winter/spring production more programmable for faster finishing and more color over the plant at sell date.

Home gardeners will enjoy plants that continue to flower through the winter in mild climates, will tolerate light snow cover and continue to flower once the snow melts off the plants. In moderate climates, Endurio will go dormant under snow cover and will grow and flower the following spring once temperatures warm up and snow melts. The Endurio series is supported by Syngenta Flowers' Winter Survivor promotional plant guarantee program.

For 2009, 'Endurio White' has been added to the series for a total of seven colors and a tricolor mix.


Endurio violas are available as raw seed with total germination over 90 percent and as Prenova, a pre-germinated seed product form for growers seeking maximum reliability when sowing under stressful high-heat conditions of summer/fall production.

Sow seed into a high-porosity seedling mix, cover lightly with coarse vermiculite, place trays in germination chamber and maintain optimum germination temperatures of 68-70¡ F. Remove seedling trays from germination chamber as soon as seedlings have emerged to avoid seedling stretch. Maintain pH of 5.5-6.0 and EC of 0.5 using a calcium-based fertilizer until first true leaves have expanded; then begin to increase EC to 0.75 in week two. Continue to increase EC in seedling tray to reach an EC of 1.0 in the plug tray at transplant. Plugs should be kept moist but not saturated. Lighting plugs is neither needed nor recommended. B-Nine (daminozide) or A-Rest (ancymidol) can be used to tone seedlings as needed until transplant.


Select a porous potting media that will provide the plant with good air space during cool temperature production and transplant plugs promptly. Holding plants in plug stage has been shown to cause a delay in flowering later in production. Fertilize plug trays the day prior to transplant to ensure that the EC of the plug tray is higher than that of the potting media where the plants will be transplanted.

Growing On

Acidify irrigation water as needed to keep media pH at 5.5-6.2 throughout production, and avoid pH over 6.5 to prevent Thielaviopsis. Maintain a media EC of 1.0-1.5 using a rotation of ammonium- and nitrate-based fertilizers to achieve optimum plant growth and toning as well as necessary pH control in media.

Violas tend to be more sensitive to boron deficiencies than other bedding crops, and deficiencies are more prevalent during periods of warm/hot weather when more frequent watering is necessary to keep plugs/plants moist. Maintain media pH of less than 6.0 and provide adequate nutrition to ensure that boron is readily available to the plant. If symptoms of boron deficiency develop, a one-time application of Solubor and reduction of pH in the media will help to overcome this problem.

High light levels will produce the most dense and closely branched plant. Violas respond to DIF, B-Nine and A-Rest. Watch the crop for signs of pests, aphids in particular. Also, proactively watch for symptoms of common viola diseases, including Thielaviopsis root rot, downy mildew, Alternaria leaf spot or Cercospora leaf spot, and treat for them as needed. Preventive fungicide drenches may be beneficial when growing viola under high-stress conditions of summer/fall production.

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Heidi Doering

Heidi Doering is product development manager for Syngenta Flowers. She can be reached at [email protected]

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