Mini poinsettias offer a different look

Poinsettias are still the most popular potted plant for Christmas. The traditional, single-pinched poinsettia is the most common form produced in the United States. But other shapes and sizes can be produced.

One way to increase sales for poinsettias is to offer something different like a mini poinsettia grown in a 2 1/2- or 3-inch pot. Mini poinsettias are already very popular in Europe with 10 million to 12 million 2 1/2-inch pots produced annually.

The mini poinsettia offers an inexpensive niche item for consumers with limited living or desk space. From a practical, money-saving point of view, mini poinsettias offer a high-density, short production cycle option.

Jack Williams of the Ecke Ranch suggests that mini poinsettias allow the production of up to 15 percent more plants per square foot using cultivars like the Jester series and Winter Rose types without compromising quality. Even cultivars like Advent Red and Prestige Early Red produce about 10 percent more per square foot.

Handling cuttings

Before beginning production of mini poinsettias, determine the desired sell date. Usually this is the last week in November, which is week 48 this year. Also, determine whether plants will be started from rooted cuttings or unrooted cuttings. Inform cutting suppliers which cuttings will be used for mini poinsettia production. This will help to ensure that suppliers provide cuttings of adequate size for this finished form. Otherwise, suppliers may provide cuttings that are too long to finish as mini poinsettias.

One of the best ways to keep a mini poinsettia short is to plant the cuttings as late as possible. For non-pinched plants, rooted or unrooted cuttings can be planted directly into the final pots during week 37. If the rooted cuttings have a well-developed root system, they can be planted early during week 38. If a pinched mini poinsettia is the goal, then cuttings should be planted earlier during week 35 or 36.

The plants should be watered-in well after cuttings are planted. Mist the cuttings frequently, especially if the weather is hot and sunny.

Pinching plants

If poinsettias are going to be grown as multistem plants, they can be pinched during week 38, which is about seven days before the beginning of short days. Mini poinsettias can be pinched later than plants in larger pots because there is no need to increase height. When pinching, leave three to four nodes per plant for most cultivars. For Winter Rose cultivars, pinch so that four to five nodes remain.

Usually poinsettias initiate flowers in late September when long night conditions occur. Consider the cultivars grown because there are genetic differences that affect the time of flower initiation and how many nodes to leave when pinching.

Production considerations

Fertilization. Poinsettias should be fertilized regularly with 200-250 parts per million nitrogen using a calcium nitrate plus potassium nitrate (Cal-Mag) formulation (i.e., 15-5-15, 14-0-14 or 13-2-13). If plants look a little chlorotic, they can be “greened up” with an occasional application of 20-10-20 or 15-15-15. Avoid using too much ammonium nitrate fertilizer, as it encourages plant stretching and leaf expansion.

Fertilization can be reduced to 50-75 ppm nitrogen or discontinued during the last two weeks of production if the plants are green and healthy looking. Leaching the growing medium with one to two applications of clear water before shipping will help to prolong the postharvest life of the plants.

Insect control. Place yellow sticky cards around the plants to monitor for early infestations of whitefly. Treat plants early if whiteflies are seen. Lewis mite is another pest that can be quite subtle at first. It looks like nitrogen deficiency. It can be easily controlled with miticides.

Height control. The final height of mini poinsettias should be proportional to the pot. The final height including the pot should be approximately 8 inches. Height can be controlled using several methods.

The growing medium in the small pots tends to dry out quickly, and if kept on the dry side, helps to maintain a shorter plant. High-light intensity also helps to keep the plants short.

Pots can be spaced at six per square foot if plants aren’t pinched. If they are pinched, grow them at five per square foot.

Plant growth regulators can control height. Apply Cycocel at 1,000 ppm weekly beginning seven to 10 days after transplanting and continuing until week 42 (three weeks after flower initiation). Bonzi sprays can be applied at 5-10 ppm until short days begin. Bonzi can also be used as a light drench (0.25 ppm) late in the crop, if needed.

Special notes. The small pots mini poinsettias are produced in are easy to knock over when watering, especially as the plants grow taller and the bracts develop. Choose a 2 1/2- or 3-inch pot that fits into a preformed tray. Not only will this prevent the plants from falling over, but the preformed trays are a good way to space plants.

Daily watering is essential as plants grow larger. Toward the end of production, plants may need to be watered twice a day.

Legend: *** Excellent; ** Very good; and * OK.

Trials were at Cornell University Long Island Horticulture Research and Extension Center in 2006 and 2007.

- Mark Bridgen

Mark Bridgen is professor of horticulture and director, Cornell University, Long Island Horticulture Research and Extension Center, (631) 727-3595; pb27@cornell.edu.

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August 2008