February 2013 Culture

Crop Culture Report: Petunia Crazytunia Series By Marc Englert

Westflowers by the German breeder Westhoff is shaking up the vegetative petunia category with its Crazytunias ­— a collection of unique petunias with exciting flower colors and patterns that are grower and consumer friendly.

‘Crazytunia Black Mamba’ is considered by some growers to be one of the best black petunias currently on the market — no striping or fading of its large, open flowers on a uniform, mounding plant habit. Other exciting varieties are Bitter Lemon, Mandeville and Pulse. Sparky’s irregular flower color and pattern is consistent in all produced plants with flower patterns ranging anywhere from lemon to magenta, uniquely in each plant. ‘Crazytunia Red Blues’ is one of the most vibrant red petunias available and ‘Crazytunia Cherry Cheesecake’ has won prizes in this past summer’s garden trials, due to its intense red and white candy cane star pattern.

The sub-series Crazytunia Twilight includes Twilight Lemon, Twilight Blue and Twilight Red. These three varieties have a matching compact mounding plant habit with psychedelic morn colors.

Westflowers has just begun with its Crazytunia collection. Expect to see more introductions this year at California Spring Trials.

Rooting and Transplant

Start with healthy, clean cuttings from a reliable URC supplier. For best results, stick cuttings as soon as possible and no later than 24 hours after arrival at your nursery. If cuttings cannot be stuck the same day of arrival, store immediately in refrigeration.

Use a well-drained soil mix with pH levels between 5.4 and 5.8 and mist for the first five days as needed; be careful not to drench liners. Remove from mist promptly and increase light levels as roots emerge. Early plant growth regulation and increased light levels with reduced mist volume will eliminate the need to pinch. Begin feeding with 200 ppm as roots emerge. Transplant after 21 to 24 days in propagation.

Transplant liners in a well-drained soil mix with a pH of 5.4-5.8.

Pinching

Crazytunia varieties may be pinched one to two times. Pinch 10 to 14 days after transplant only if B-Nine applications were missed or significant stretch occurred in propagation. Petunia ‘Crazytunia Mandeville’ is more vigorous and requires two pinches.

Temperature and Lighting

Maintain night temperature between 52 and 62° F and day temperature between 58 and 75° F.

Crazytunias should be grown under high light levels (between 5,000 and 8,000 foot-candles is ideal). Low light levels will cause stretching and reduced plant quality. They flower best under long days of spring and summer. Strongest flowering is April to September. Shorter day length causes longer crop times. Fastest flowering during short day length can be achieved by maintaining night temperatures at 58 to 60° F and using lighting to extend day length to 12.5 hours.

Water Supply and Fertilizer

Uniform water management is important; avoid plants standing in water or overwatering. Allow media to dry between watering. Avoid periods of continued wilting. Petunias are sensitive to both drying out and being too wet; manage water and humidity to reduce occurrences of Botrytis and root diseases. To help prevent foliar diseases, water early in the day and avoid high humidity, constantly saturated media and wet foliage.

Crazytunias have a high feed requirement. Use constant feed with a balanced fertilizer at 250- to 300-ppm nitrogen with additional iron as needed. Provide a full complement of minor elements to the plant.

Plant Growth Regulation

Combination of high light levels and cool temperatures are the best growth regulator. One or more applications of B-Nine (1,500 to 2,500 ppm) starting seven to 14 days after transplanting will control growth and improve flowering. To optimize flower size and avoid delay in flowering, avoid B-Nine applications in the final four weeks of crop time.

To slow vegetative growth while allowing flowering to continue of mature plants approaching shipping size, drench with Bonzi (0.25-1.0 ppm). Frequent applications of growth regulators at a lower concentration early in the crop cycle will produce best results.

These recommendations for plant growth regulators are general guidelines. Growers must trial all chemicals under their particular conditions.

Crop Time

Starting from a URC: 10 to 12 weeks for a 1-gallon pot with one plant per pot; 11 to 13 weeks for a 10- to 12-inch basket with three plants per basket.
Starting from liners: seven to nine weeks for a 1-gallon pot with one liner per pot; 8 to 10 weeks for a 10- to 12-inch basket with three liners per basket.

Pests and Diseases

Keep an eye on: thrips, white fly, aphids, leaf miners and fungal gnats, as well as Botrytis, Rhizoctonia and Pythium. Avoid low temperatures, low light levels and overwatering.