The Problem ADVANCED TECHNIQUES IN CUT FLOWER PRODUCTION: INCREASING STEM LENGTH AND STRENGTH. Where Are You Growing It? What Can I Do About It?

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1 ADVANCED TECHNIQUES IN CUT FLOWER PRODUCTION: INCREASING STEM LENGTH AND STRENGTH John Dole The Problem It has a great flower, produces a lot, and lasts a long time, but.. Its too short! Its too weak! What Can I Do About It? Change cultivar or Where Are You Growing It? Field vs. high tunnel vs. hoop house vs. greenhouse Different levels of environmental control Change how you grow the plant: Production methods Chemicals 1

2 Temperature Optimum production temperature DIF Optimum Temperature Increasing: Day temp up to the optimum temperature, increases photosynthesis (good) and respiration (bad) Night temp, increases respiration (bad) Optimum temperature varies with the species: Cool weather crops have a low optimum temperature Delphinium: 50 to 55 o F night, 70 to 80 o F day Warm weather crops have a high optimum temperature Celosia: 65 to 72 o F night, 70 to 90 o F day When Temperatures are too Warm? Daily Temperature Plants are short Stems thin Branching reduced Insects and diseases more common Average daily temperature controls rate of development High + Low = approximate average daily temperature :00 AM 6:00 AM 11:00 AM 4:00 PM 9:00 PM DIF DIF The difference between day and night temperature The greater the DIF, the greater the stem elongation No effect on some species DT 57 o F DT 86 o F NT 86 o F NT 57 o F 2

3 DIF Changing Height DIF Changing Flowering Time House A B C Day (12 h) 75 o F 65 o F 70 o F Night (12 h) 65 o F 75 o F 70 o F DIF Height Tall Short Interm. Average daily temp. 70 o F 70 o F 70 o F House A B C Day (12 h) 75 o F 80 o F 65 o F Night (12 h) 65 o F 70 o F 55 o F DIF Height Tall Tall Tall Average daily temp. 70 o F 75 o F 60 o F What Can I Do? Grow at the optimum temperature for the species, especially the night temperature In the greenhouse or hoop house, let the day temperature get warm (high DIF), balance with a cooler night temperature to keep the same schedule temperature Light Effects Light Intensity Intensity Decreasing light, increase stem elongation Quality Red:far-red light Duration Photoperiods required for flowering 3

4 Plant Spacing Increasing the number of plants/bed will: Increase red:far-red light ratio Decrease the amount of light each plant receives Increase stem length Increase number of stems/bed May decrease stem quality and increase diseases Light Quality Zinnia Benary Giant Scarlet 32 plants/plot Produced more stems Had more disease (1= good, 9= bad) Photoperiodism Photoperiodic types Short day Long day Day neutral Combinations Photoperiodism Increase height by increasing time between noninductive photoperiod and inductive photoperiod For example, with a SD plant, grow under LD longer before putting under SD. 4

5 Crop Scheduling Goldburst Sunflower Species Plant January Plant June Campanula Tall Short Celosia Short Tall Asiatic lily Tall Tall May 19-May 2-Jun 16-Jun 30-Jun 14-Jul Length (inches) Days to harvest Forest Fire Celosia What Can I Do? May 19-May 2-Jun 16-Jun 30-Jun 14-Jul Length (inches) Days to harvest Use shade Space plants closer together Manipulate photoperiod Nutrition Increasing nutrition, increases growth Soluble salt levels in the media: Too high, shorter plants (stunts roots) Too low, shorter plants (stunts shoots) Increasing ammonium tends to increase stem elongation and leaf size compared with nitrates 5

6 Water Any water stress may reduce cell elongation and plant height Standard irrigation practice water when upper surface of medium is dry Pulse irrigation water once or twice a day regardless of the plant s water status increases height Air Movement Reduced air movement and increases humidity, which increases stem length Campanula Lisianthus Trachelium Stems generally long in high tunnels, hoop houses, and greenhouses Use wind breaks in the field Production Methods Direct seed vs. transplants Pinch vs. straight up or single stem Remove lateral buds Beds vs. containers Cosmos Double Click Direct seed Longer stems More stems 6

7 Chemicals: Gibberellic Acid Dianthus Bouquet Purple GA Applications (ppm) Increases stem elongation Breaks dormancy Length (inches) Two week harvest periods Dianthus Bouquet Purple Use 400 ppm Apply every 3 to 4 weeks starting when plants are established and flower stalks are visible Using GA Achillea Summer Pastels 400 to 800 ppm Apply every 6 weeks starting when plants are established Celosia Toreador Red 1600 ppm Apply every 4 to 5 weeks starting when plants are established and flower heads are visible. Using GA Using GA Dianthus Amazon Neon Larkspur Imperial Giants Pink Perfection 200 to 400 ppm, one to two applications Apply every 3 to 4 weeks starting when plants are established and flower stalks visible Digitalis Camelot White 800 ppm Not recommended due to flower malformations Zinnia Benary s Giant Scarlet 800 ppm Apply every 4 to 5 weeks starting when plants are established and flower buds are visible Will reduce flower size 7

8 GA Problems Questions/Comments Distortion of flowers or foliage Excessively large or light green leaves Following problems are less common in field than in greenhouse: Weak, thin stems (use netting) Delayed flowering Decreased postharvest life 8