February 2005

Callafornia Calla Lilies

An under-used and high-margin crop, calla lilies, make a great addition to any pot plant program. Recent breeding has created varieties that are disease resistant and friendlier to smaller formats. Last year’s new introductions from Golden State Bulb Growers (GSBG) typify this trend.

‘Gold Rush’ has rich yellow flowers with a somewhat variable form; heavy, upright extremely sturdy stems; and a deep matte-green, spotted, arrow-shaped leaf. It is less disease susceptible and works well as a large pot variety. ‘Peach Chiffon’ has peach/apricot bicolor flowers with sturdy stems set against broad green, ovate leaves. It has prolonged flower production, with old flowers reverting to “leaf” appearance and, works well as a mid-sized plant.

The following culture information was compiled from information from GSBG.

Propagation

Make sure to unpack dormant tubers upon arrival, and place them in well-ventilated trays at 65° F for a couple of days prior to planting to ensure that any possible friction wounds caused by transit are healed before planting. For long-term storage (six weeks or more), keep well ventilated at 50° F and with a relative humidity of 80 percent.

Plant tubers with about 1-11?2 inches of media over the tuber, rounded side down, sprouts (eyes) up.

Use a 30- to 50-percent coarse grade, well-drained, peat-based media with a pH of 6-6.5 and good air porosity. Lighter formations, using less peat, are suitable for cooler, early winter plantings. Higher proportions of peat are sometimes used by experienced growers, but at the risk of enhancing diseases.

Incorporation of gypsum/lime will help not only pH balance, but provide calcium for good plant health. A light two-week starter charge of a balanced fertilizer will help plants get off to a fast start.

GSBG recommends incorporating Trichoderma biologicals such as Root Shield or Soil Guard into the media 3-7 days before planting to promote optimal root health, especially where fungicide labels are restricted.

Growing On

Finishing time decreases as the planting date is moved later in the year. Warmer temperatures and longer days accelerate growth. When potting Peach Chiffon or Gold Rush during October-December plan on 2-3 weeks more bench time to reach peak bloom. Also, plan on using additional Bonzi, maintaining cooler finishing temperatures and optimizing available light. With no exact scheduling perfected, some approximate average forcing times for Peach Chiffon and Gold Rush are as follows: In January and February, first flower is approximately nine weeks, with peak (GA induced) at 10-11 weeks. March-May, first flower is in approximately eight weeks, with peak (GA induced) at 9-10 weeks.

Temperature. Recommended temperatures for Gold Rush and Peach Chiffon are stage dependent.

• Stage 1: Twelve-25 days from planting, when 1- to 3-inch sprouts appear, maintain 75° F days and 65° F nights or a consistent 68° F.
• Stage 2: Days 28-50. Maintain 70-75° F days and 60° F nights (nights can be cooled an additional 2-5° F if light is poor or extended bench time is desired).
• Stage 3: Days 50-75. Maintain 65° F day and 50-55° F nights.

According to GSBG, the only way to speed bloom in callas is to increase temperatures. But warm temperatures, especially under low light, will produce taller, softer plants. So it is better to plant early and slow down with cooler temperatures than to plant late and have to add heat in Stages 2 and 3.

Water Management. Water management for these varieties is critical. Keep the pots moist, but avoid excessively wet conditions. Good quality water at an EC below 1.5 sustains plant quality, growth and overall health.

Fertilization. The ideal starter fertilizer charge would be a 10- to 20-day soil-incorporated application of 15-3-15, avoiding ammonia forms of nitrogen. GSBG recommends using a constant 150- to 200-ppm bala

PGR. Bonzi is the most effective growth regulator and plant “toner” for callas, according to GSBG. Apply Bonzi when all sprouts have emerged and are between 0.5 and 3 inches tall. It is best applied a day or two after an irrigation or the second fungicide drench. Segregate pots by sprout size, treating tallest pots first. Then when slower pots reach size drench these pots also. Second and subsequent applications are usually made 6-10 days after the previous one.

Pests/Diseases. Control of fungus gnats and shoreflies is important due to their ability to spread bacteria and disease. Generally, callas are relatively tolerant to phytotoxicity, and label rates of most insecticides can be used safely. Control on an as-needed basis for white flies, aphids and thrips are recommended. Always watch for Erwinia-infected plants and carefully remove and discard. For more information on growing Peach Chiffon, Gold Rush and other California Callas visit www.goldenstatebulb.com.

Callafornia Callas?

What can I tell you about callas that you don’t already know? Maybe not much, since they’ve been around for a long time, but just look at the bold new colors that have surfaced in the last few years from GSBG. Gold Rush and Peach Chiffon are just two of the newest examples. With all of the new pinks, creams and plums, along with their many uses, calla lilies can no longer be considered just a funeral flower.

One more thing I have to get into this little column is the versatility of this crop. Pot crop, cut flower and even in the landscape — calla lilies give you many options. And the growing popularity of mixed containers makes Callafornia Callas an even more obvious choice.

— Carrie Burns