July 2014 Culture

Perennial Solutions: Oriental Lily Roselily Series By Paul Pilon

If you like Oriental lilies, the spectacular new Roselily series of double Orientals from Zabo Plant may soon become your new favorite type of Oriental lily. This series features double flowering cultivars, which are pollen free and have a light, pleasant fragrance. That’s right, no more pollen on clothing after handling this series, and the strong overbearing aroma of most Orientals has been reduced to a delightful scent. Additionally, the individual flowers last approximately four days longer than most Oriental lilies, which means more longevity at retail or a longer vase life.

Although referred to as double Orientals, the Roselily cultivars are selected to have at least 18 flower petals, which is 12 more petals than cultivars with single flowers; this truly distinguishes the Roselily series from other double Orientals on the market. The series name Roselily reflects the rose-like appearance of the open flowers.

The first generation of Roselily consisted of two cultivars: ‘Roselily Belonica’ (light pink) and ‘Roselily Fabiola’ (soft pink and white). The second generation currently consists of eight additional cultivars and are selected to have more upright facing flowers: ‘Roselily Annika’ (white with green stripe), ‘Roselily Carolina’ (white), ‘Roselily Celina’ (pink), ‘Roselily Elena’ (pink), ‘Roselily Felicia’ (light pink), ‘Roselily Isabella’ (rich pink), ‘Roselily Natalia’ (light pink) and ‘Roselily Thalita’ (red).

In the landscape they can be grown in locations with partial to full sun throughout USDA Hardiness Zones 3 to 10. The Roselily cultivars grow 24 to 30 inches tall. Oriental lilies can be grown and marketed as potted plants, containerized perennials, for cut flower production or used in the landscape. They can easily be scheduled for sales around major holidays, during the spring sales windows or throughout the year. With its impressive pollen-free double flowers and light fragrance, the Roselily series is sure to attract attention and would make a great addition to most perennial programs.

Propagation

The Roselily series originates from tissue culture and is not practical for growers to propagate on their own. Additionally, plant patents have been applied for (PPAF) these cultivars and any propagation is strictly prohibited. Growers can purchase fully mature, pre-cooled and ready-to-plant bulbs for planting into their final containers.

Production

Growers receive pre-cooled, frozen bulbs packed in peat moss. Gradually defrost the bulbs at 50 to 55° F for several days prior to removing them from the peat moss and planting. Once they have thawed, the bulbs can be separated from the peat moss, taking care not to break off the scales of the bulb during sorting. The bulbs will begin to sprout after thawing; plant them immediately after thawing and before the stems have emerged to avoid breaking the delicate shoots.

The Roselily series is suitable for production in 1-quart to 2-gallon containers. Oriental lilies perform best when they are grown in moist, well-drained growing mixes. The number of bulbs to plant into each pot varies with the container size, customer specifications and the price point of the final product. Growers typically plant one bulb per pot in 1-quart containers and three bulbs in 1-gallon pots.

Plant the bulbs deeply with a minimum of 3 inches of growing mix above the top of the bulbs; there should also be at least 1 inch under the bulb. A proper planting depth is important to provide adequate stem root development for uptake of moisture and nutrition as well as for developing stems roots which supports or anchors the plant when it flowers. To improve plant appearance, take care to plant the bulbs pointed upwards, not sideways. Watering them in thoroughly after planting ensures good contact between the growing mix and the bulbs, which improves the uniformity of emergence.

After planting, keep the media uniformly moist until the plants have emerged. The soil should never be allowed to dry out, while at the same time it must not be kept overly wet during this crop stage. They have an average water requirement after emergence. Once the flower buds are visible, the growing media should never dry out as overly dry conditions at this stage could cause the flower buds to abort. In fact, it is recommended to increase the moisture content once the buds are 0.5 to 1 inch in size to promote bigger, more robust flowers.

Like other Oriental lilies, the Roselily series perform best when grown at light-to-moderate fertility levels and a neutral-to-slightly acidic pH (6.5 to 6.8). Begin fertilizing with 150- to 200-ppm nitrogen weekly or with 75- to 100-ppm nitrogen with every irrigation when the plants are 2 to 3 inches tall.

Due to their intermediate plant size (24 to 30 inches), it is often beneficial to dip the bulbs in 5-ppm uniconazole (Concise or Sumagic) solution for two minutes prior to planting. Pre-plant dipping in PGR is more necessary during winter production than when growing them later in the spring or summer. Spray applications of 5-ppm uniconazole are effective at reducing stem elongation if additional height control is necessary during production.

Insects and Diseases

Oriental lilies can generally be produced without the incidence of pests or diseases. Aphids, fungus gnats and shore flies are the most common insects growers may observe on occasion. Botrytis, Pythium and Rhizoctonia are the diseases that occur most frequently. Significant crop injury or losses from these pests and diseases are not common. These problems can be detected with routine scouting and usually do not require preventative control strategies.

Temperature and Scheduling

Temperature is the most important factor influencing the production of Oriental lilies. To optimize emergence, growth and development and flower timing, it is beneficial to manage temperature slightly differently at various stages of production.

Providing proper temperature starts as soon as the lilies are planted. Initially, the soil temperature is more important than the air temperature. To improve the uniformity of emergence, it is best to maintain soil temperatures of 55° F. Emergence takes approximately two weeks at these temperatures, but may take slightly longer when the soil temperatures are lower.

After emergence, switch to monitoring and providing the proper air temperature. Oriental lilies prefer to be grown warm. The optimal temperature for growth and development is 68° F. I recommend providing 65° F night temperatures and 70° F day temperatures. Providing cooler temperatures will delay crop development and increase the production timing. Conversely, warmer temperatures will hasten crop development. It is recommended to avoid night temperatures below 59° F. Low night temperatures greatly decrease crop performance as well as increase the production time.

The production times of the Roselily series vary from 95 to 125 days. At the temperatures described above, the estimated finishing times for the Roselily cultivars are:

13.5 weeks — ‘Elena’

15 weeks — ‘Felicia’ and ‘Isabella’

15.5 weeks — ‘Belonica’, ‘Carolina’, ‘Celina’, ‘Fabiola’, ‘Natalia’ and ‘Thalita’

17.5 weeks — ‘Annika’

The above finishing times are based on late winter/early spring production. The production times for most of the cultivars will be reduced by approximately two weeks when they are grown in the late spring or early summer.

The color of the blooms is more intensified and the size of the flowers will be larger when they are grown slightly cooler during the last couple weeks of production (60° F night and 65° F day).

Availability

Ready-to-grow bulbs of the Roselily cultivars of double flowering Oriental lilies are available from Zabo Plant USA (www.zabo
plant.com).