While good culture in the propagation environment is imperative, how unrooted cuttings are handled upon arrival is also a very critical part of successful poinsettia production.
Most growers in North America receive unrooted cuttings from an offshore facility in Mexico or Central America. Cuttings for Ecke customers are harvested from stock in Guatemala and delivered within a maximum of 72 hours after harvest.
Cuttings are typically wrapped in moist paper and placed in bags of 100. The cuttings are packed in boxes that have been precooled to 55º F prior to shipping. Ice packs are also used; the amount of ice used will vary depending on the weather outlook at the cutting’s final destination. During summer months many cuttings will be re-iced upon entrance into the United States through Miami or Los Angeles.
Throughout the shipping process the cold chain is maintained to assure our customers receive the freshest cuttings possible. Once cuttings arrive it is critical the growers process cuttings immediately. If cuttings can’t be stuck immediately upon arrival the cuttings should be placed in a cooler (50-60ºF) and stuck within 24 hours. Many growers have found added benefits to pre-cooling cuttings and schedule sticking accordingly. When cuttings are pre-cooled wilting on the propagation bench is less problematic. The cuttings generally restore their turgidity with less mist volume required which is beneficial in increasing the speed to rooting time. Less misting also reduces the incidence of disease and fungus gnats. Boxes can be placed directly in the cooler however it is more difficult to reduce the core temperature of the box if the boxes aren’t open. For best results the cuttings should be removed from the boxes and bags and placed in trays. Misting the cuttings before they go in the cuttings also helps; some growers processing large volumes are equipped with coolers with misting systems installed.
During the sticking process cuttings should be removed from the cooler in quantities that can be stuck immediately. Do not allow cuttings to sit in a warm environment or in the sunlight for too long. In a warm summer greenhouse it only takes 10 minutes for a cutting to permanently wilt. That’s why it’s also important that mist systems are ready to go and the cuttings are misted as they are placed on the bench. Initial misting frequency will vary depending on light intensity, air movement and humidity. An ideal initial misting frequency will provide a constant film of water on the leaves, maintain the humidity at near 100%, and supply little or no water to the rooting medium.
Before cuttings go on the bench it’s also important to make sure the light levels are in check. Shade cloth should be used initially so that cuttings receive 1000-2000 f.c. during the brightest part of the day. Levels in excess of 2,000 f.c. will result in excessive wilting and possible scorching. It will also increase the amount of mist required to keep the cuttings turgid.
Excessive ventilation should also be avoided as high humidity is essential in preventing wilting. As the cuttings are being stuck humidity levels should be near 100%.
Proper planning, scheduling, and ensuring your propagation environment is ready to go when cuttings arrive will go a long way in ensuring the success of your poinsettia propagation. Stress during the sticking process is not easily overcome in the later stages of propagation. Wilting, leaf yellowing, and disease can all be issues when a cutting is stressed and can easily reduce the performance of a cutting. Simple, proper handling techniques can easily prevent issues.
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