Sriracha Cuphea: Some Like it Hot

Matt Blanchard

Sriracha cuphea is an all-new, heat-loving series from seed that features quick crop timing of 7 to 8 weeks from transplant. Its compact, well-branched habit offers excellent series uniformity suitable for quarts, 6-in. or gallon containers. Available in three colors—Pink, Rose and Violet—Sriracha provides vibrant color from spring through the heat of summer.

Germination
Sriracha can be sown in 105 to 288-cell plug trays with one seed per cell. Covering the seed is optional, but using coarse-grade vermiculite will help maintain moisture levels. The relative humidity should be held at 95% to 100%, at least until radicle emergence.

Light is not required for germination, but the media temperature needs to stay between 70 to 75F (21 to 23C). Maintain a saturated moisture level (level 5) until radicle emergence, which usually occurs in 3 to 5 days.

The application of a plant growth regulator (PGR) is critical during sowing. To control hypocotyl stretch, spray or sprench media surface with 1 ppm paclobutrazol at a volume of 3 to 6 qts./100 sq. ft. within 48 hours of sowing seed.

After germination, increase light levels to 1,500 to 2,000 foot candles (4 to 8 mols/day), begin alternating moisture levels between wet (level 4) and moist (level 3), and lower the relative humidity to 40%. During this stage, use fertilizer as needed, specifically 14-4-14 or 17-5-17 at 50 to 100 ppm Nitrogen.

Plug bulking
Air temperature should be maintained at 70 to 75F (21 to 23C), but light levels should increase to 3,000 to 4,000 foot candles (10 to 16 mols/day). The relative humidity should stay between 40% to 50%, allowing the media to dry back to level 2 before re-saturating to level 4.

The pH level should stay between 5.8 to 6.2, while the EC should stay between 1.0 to 1.3 mS/cm. Fertilize at 100 to 150 ppm Nitrogen, preferably with a Cal-Mag fertilizer. PGRs are generally not required during plug finishing if paclobutrazol was sprayed at sowing.

Time to finish 288-cell trays is usually 3.5 to 4 weeks, but the timing will vary based on the growing environment and culture.

Growing on
Sriracha is ideal for multiple container sizes. One plug/pot is needed for quarts and 6-in. containers, while two plugs/pot are needed for 8-in. containers and gallons.

Daytime temperatures should stay between 70 to 85F (21 to 29C) and decrease to 62 to 70F (16 to 21C) at night. For shorter finishing times, maintain a minimum average daily temperature (ADT) of 68F (20C). Grow under 3,500 to 5,500 foot candles of light (12 to 20 mols/day). While short days are not required, flowering will be 1 to 1.5 weeks faster with day lengths less than 12 hours.

Be sure to use porous media with good drainage while keeping the relative humidity at 40% to 50%. High relative humidity in combination with overwatering and light conditions can cause intumescence (edema) on leaves of some varieties.

Sriracha has a moderate fertility requirement. Keep EC between 1.8 to 2.2 mS/cm. Alternate between Cal-Mag and ammonium-containing fertilizers at 150 to 200 ppm Nitrogen. For growth control, use Bonzi plant growth regulator sprays at 20 to 40 ppm or Bonzi drenches at 0.5 to 1 ppm. One or two applications are generally needed. Late applications can delay flowering. Plants are more compact when grown under short days versus long days. Pinching is not recommended since Sriracha has excellent branching without the need to pinch.

Finish time will vary depending on plug size and growing environment. At an ADT of 73F (22C) and under long days with a daily light integral of 12 to 15 mols/day, crop time from transplant of 288 cell plugs is 7 to 8 weeks.

Diseases, pests & controls
To control pests, it’s recommended to use Bioline biological control agents:

For complete Sriracha cuphea culture, please visit http://tsl.syngenta.com/. For more information, please visit www.syngentaflowersinc.com or call (408) 847-7333. GT

Matt Blanchard is a Technical Services Specialist for Syngenta Flowers, Inc.