August 2002

Ranunculus Bloomingdale By Corinne Marshall

Ranunculus Bloomingdale is not only a stunning variety, butan indispensable item for early spring sales. Its bowl-shaped flowers resemblesmall peonies and produce densely petaled blooms in nine colors: Pure Yellow,Tangerine, Golden Shades, Pink Shades, Red Shades, Rose Shades, White Shades, amix and the new Purple Shades. The shade colors are very attractive with richcolor variation on each plant. Suitable for 4-inch and larger pots, the large,full double flowers are borne on sturdy stems.

PLUG STAGE

Stage One (day 1-14). Usea sterilized soil media with plenty of organic matter, (a mixture of 30 percentpeat and 70 percent perlite has been found to be highly efficient andaccelerates germination and seedling growth. A pH of 6.0-6.5 is recommended forbest results. Cover seed with a very thin layer of soil or peat/perlite mixtureand water thoroughly. Select a well-ventilated environment and avoid strongsunlight. Place seed flats in the coolest possible location in the greenhouse,50-60º F. Never allow the growing media to dry out until the seedgerminates.

Stage Two (day 15-21).After seedlings begin to emerge, reduce moisture and place flats in awell-ventilated and shaded greenhouse (2,000-3,000 foot-candles) and maintain55-60º F days and 40º F. Apply a light fertilizer of 100 ppm nitrogento strengthen seedlings.

Stage Three (day 22-42). Maintain cool greenhouse conditions, and do not allow air temperaturesto exceed 77º F during this period. Fertilize every 10 days with 100-150ppm nitrogen and maintain EC levels between 0.7-1.0 (saturated paste 2:1).Ranunculus is sensitive to excess salt levels so avoid stressing the plantswith temperature and moisture.

Stage Four (day 43-50).Seedlings have developed four true leaves and are now ready for transplantinginto pots. Ranunculus becomes reproductive at the fourth true leaf stage. Latetransplanting creates smaller plants with poor foliage and plant bodydevelopment.

GROWING ON

When seedlings reach the fourth true leaf stage, transplantthem into 4- and 5-inch pots with a starting soil pH of 6.0-6.5. Select ahighly fertile soil with good drainage, low in peat contents, with abundantorganic matter and well-rotted leaf mulch. Initial growth after transplantingwill be slow. It is important to maintain temperatures as low as possible,55-60º F, never allowing daytime temperatures to exceed 77º F. Placeone plant per 4-inch pot and three per 5-inch pot, being careful not to damagethe delicate root system.

Approximately two months after sowing, plants will begin togrow rapidly. Ranunculus requires high nutrition. Either incorporate fertilizerinto the potting medium or apply a commercial liquid feed every 7-10 days.Water thoroughly and regularly, and if grown with heat, monitor the temperaturecarefully. Young seedlings should not be subjected to long days, as this willcause the plants to form corms, resulting in insufficient growth and budformation delay. Allow sufficient space between plants on benches to enablemaximum growth at all times. Also, monitor boron carefully as Ranunculus issensitive to low levels.

Finishing

Approximately 1-1 1/2 months after potting, plants shouldgrow to a reasonable size. Crop time from sowing is 5-5 1/2 months, dependingon temperature. For early pot sales, maintain a daytime temperature of60-68º F and a night temperature of 44-50º F.

At higher temperatures, both stems and leaves may showexcessive growth. Applications of B-9 at the rate of 2,500 ppm will yield goodresults. B-9 should be applied when buds first show at the base of the plants.To control flower stem stretch, lower temperatures, regulate watering and providegood air circulation.

The most common insects are aphids, leaf miners and spidermites. Major diseases include wilt, Botrytis and powdery mildew, all of whichcan be controlled by spraying. Good culture and nutrition will create healthyplants that are less susceptible to disease.

Growers often wish to produce an early crop of Ranunculus,germinating and growing young plants in the heat and long days of summer. Underthese conditions plant growth often stalls or plants produce weak growth. Thisis because under long days — greater than 13 hours daylength —Ranunculus want to produce corms rather than vegetative growth. Providing blackout with 10-13 hours of day length will maintain active vegetative growth.