Poinsettias are the top selling potted plant in the US, and they are second to orchids in sales volume. The greenhouse crop isn’t very profitable, however it’s practically required for cash flow at this time of year. There are about 120 different cultivars of poinsettias. Different varieties and plant heights can help growers differentiate from competitors.
Important Grower Tips: Preparation and planning of the crop is just as important as the actual growing. Mistakes in planning can result in many extra labor hours, raising costs! There’s many sources of cultural information on how to grow poinsettias. It’s advised that new growers visit one or two poinsettia growers, to compare crops and learn cultural tips.
Notes taken on problems, solutions, and their success and failure will be invaluable through the years when deciding what treatments are needed when. Notes should be taken variety by variety, because each preforms differently in different circumstances and regions. It’s important to take weekly pictures, record weekly activities, sunlight levels and temperatures. The next year this knowledge can be used to keep the crop on track.
Propagation: Costs of producing cuttings are too high if mother plants doesn’t yield at least 20 cuttings. These plants occupy a large amount of greenhouse space. Growers who propagate by producing their own cuttings will pinch stock plants 3 times if planted in March, twice if planted in April, and once if planted in May. Long days are provided to March and April stock plants, to keep them in the vegetative state.
Most growers buy all their unrooted cuttings from suppliers. This allows more space for more efficient crops. Cuttings for retail plants usually arrive in July or August, although they are started earlier in greenhouses with lower than average temperatures. It takes between 24 and 36 hours to ship cuttings in transit. Cuttings should be stuck as quickly as possible to prevent losses. They can be rooted in many different medias, and some growers use IBA and NAA mixes to improve rooting uniformity. Rooting cuttings takes about 21 to 28 days. New growers should start first year’s production with liners, if that’s easy move to callused cuttings or unrooted.
Cuttings should be oriented so that leaves don’t over crowd and cover the terminals. Densities of 12 cuttings per square foot work well. Soil and air temperatures should be maintained at 76-78o and 70-75o. Tempered water (70o) should be used in the mist lines to maintain soil temperature. Start with 10 seconds of mist every 6-8 minutes and adjust to rooting. Light should be maintained between 800- 1000 f.c.
Once 50% of cuttings have differentiated root initials, media can be dried between watering and light levels can be increased to 1,000 to 1,200 f.c. Fertilizer should be rapidly increased from 100 ppm 14-0-14 alternating with 20-10-20 to 200 ppm. To prevent damage, rinse leaves after applying fertilizer with phosphorous. pH and EC should be maintained at 5.8-6.2 and 1-2 mS/cm. Growth regulators can be used to prevent stretching.
The final rooting stage takes 7 days to harden the cuttings before transplant/sales. The media should thoroughly dry before irrigation. Misting can stop and the media can be watered directly. Temperature and light is increased to 72-75o and 1,500-1,800 f.c. 150-200 ppm of 14-0-14 fertilizer is be applied weekly.
Pinching: Poinsettia plants are usually pinched when the roots reach the edges of the pot, typically 2 weeks after transplant. There also should be sufficient time between pinching and short days, about 12 days in southern US and 22 days in northern. Florel can be used to increase branching. 150-500 ppm of is sprayed 1 week before and after pinching. To reduce infections, cutting tools should be sterilized between cultivars.
The most common type of pinching, that provides the most even branching, is the “hard pinch.” This removes all the immature leaves. The number of nodes left on the plant depend on the size of the pot: 4.5” pot is 4-5 nodes, 5.5” is 5-7 nodes, 6” is 6-8 nodes, and 6.5” is 7-9 nodes. 1 or 2 leaves below the pinch can be removed to reduce apical dominance and increase light levels to the lower leaves.
Summary of Project: Costs per plant were estimated, by Dr. Verlinden, to be about $4.50. Judging by the available estimations from the charts below, total costs were about $1962 or $4.36. Of the 450 plants, 250 were sold at $8 and 200 at $6, estimating $3,200 revenue. Revenue minus 20% taxes and costs is $598 net income, with only an 18% profit margin.
Problems: After moving the crop to the plastic house, we noticed some “rabbit tracks” and leaf curling. This was the result of using old fertilizer that wasn’t dissolving properly and a mistake with the injector. In growing environments with many different plant species, IPM can be more difficult because there are many different types of pests. White fly also became a problem after moving the crop to the plastic house. Marathon 1% granular was applied on Oct. 8. In order for the chemical to take effect, we watered lightly for 10 days after the application.
The fragility of the branches was a reoccurring problem with the crop. If not handled carefully, branches would fall, resulting in poorly shaped plants. This was first very noticeable after spacing in November. The same mistake was made again by a greenhouse worker, who unnecessarily moved many of the plants. This is why good communication is important in the greenhouse. Without it, mistakes are made lowering crop value and wasting paid labor hours. A very visible warning sign could be used to prevent this mistake for next year. PGRs can also be used to reduce plant height and maximize stem strength.
During spacing on Nov. 15, I noticed a few whitefly. After finding a few eggs underneath the leaves, I called IPM Laboratories and BFG Supply Co. to see what we could use on 16 (15 x 4.5ft) tables of 13 week old poinsettias. If we were to use Encarcia formosa as a bio control, we would need to do three weekly releases to treat 2000 sq. feet. They would consist of 3000, 3000, and 1000 Encarcia costing about $50 each time (including shipping) or $150 total. There would also be no major results for few week because the parasitic wasp only lays eggs in larva. Also the wasp may be affected by Marathon sprayed 5 weeks earlier. Another option was a predatory mite, Amblyseius swirski. They would be a onetime deal $75 for 100.
The pesticide options for controlling whitefly on 13 week poinsettias were: Tristar, a tank mix of Azatin and Decathalon, and Sanmite. Tristar is a locally systemic pesticide which kills adult whitefly. The tank mix would take longer to work, but also lasts longer. Sanmite would need Capsil as a surfactant, in order to stay on the leaves. We ended up using the Azatin and Decathalon tank mix because they were already available, and a more affordable option than the bio controls.
Roses: The roses had a lot more problems than the poinsettias. First we transplanted 3 rose plugs per pot, which turned out to be too many. On Sept. 27, we spent 5 hours separating 1 rose plug per 5″ pot. On Oct. 3, we spent 4 hours re-potting them to 6” Azalea pots. On Oct. 6, Marathon was applied. On Oct. 10, Avid was sprayed to get rid of spider mites. They were also pruned for 1.5 hours about every two weeks, starting Oct. 4. After thanksgiving break, the spider mite damage was very bad because they weren’t getting sprayed. Our spidermite problem was extreme because only our crop was being sprayed, while the rest of the greenhouse was not.
Conclusion: Research and preparation are two of the most valuable aspects of growing crops. Hours could have been saved if we had researched the spacing of rose plugs. The poinsettias would have been much higher quality if we had been aware of their fragile branches and communicated that to other greenhouse workers.
Let me know what you think in the comments below. Do you have any other tips for growing crops?
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Floricast. 2009. Tips For Pinching Your Poinsettia Crop. http://www.greenhousegrower.com/video/plant-culture/v-tips-for-pinching-your-poinsettia-crop/
Ball Redbook. 2011. Euphorbia pulcherrima. Pg. 372.
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