Caladiums for Pot Producers

  Competition is steadily increasing for shelf/floor space in garden centers due to the ever-increasing numbers of new plant lines and varieties.  Caladiums can withstand this competition and even grow in volume if well grown.  Caladiums are among the best buys for the consumer – however, they needed to be attracted to the plants in the first place.  There aren’t many plants that are more attractive than a well-grown caladium, though a poorly grown caladium can be a real turn off. 
  To produce a quality pot the nature of commercial varieties must be understood.  Current commercial varieties are selected to survive and even thrive under Florida conditions of high humidity, high temperatures and high (>9,000 foot-candles). 
  To produce a quality pot, these conditions must be met OR things must be done culturally to compensate.  De-eyeing, spacing, good DIF (if possible) and growth retardants go a long way in compensating for their needs.
The following are our cultural suggestions for producing a highly marketable pot caladium
De-eye all bulbs sizes #2 and larger. Match bulb sizes and quantities to the pot they are grown in. Soak de-eyed bulbs for 20 minutes in a 15-30 ppm (0.5 oz-1.0 oz./gallon) solution of Bonzi and allow them to drip dry overnight on a greenhouse bench (alternatively drench with 8 ppm at spike). Plant bulbs in a soil mix that contains a slow release feed such as Nutricote, Osmocote or Polyon.   Your soil supply company should be able to take care of this for you. Water the planted pots and place pots in germination area . Alternatively weekly balanced liquid feed. Drench with Subdue Max or other fungicide that is effective against Pythium within 10 days of potting.  As you may know Subdue does come in a granular formulation that can be mixed into your soil by your soil company saving you the trouble of drenching.  Repeat according to label. Place the pots in a very bright growing location.  Most varieties can stand 8,000+ foot-candles. If the growing facilities allow for good DIF control, better habits are achieved with 65-70°F nights and 85-90°F days. Space pots at 3 weeks.  Alternatively, since caladiums have such short crop time space them from the beginning. Spray plants with a 2500 ppm solution of B-9, 5-7 days before shipping. For smaller batches of bulbs, a Bonzi (8 ppm) drench (in stead of a bulb soak) after the spikes are up has been found effective.  Drenches are only effective after there are roots to absorb the material.  2500 ppm B-9 can be added to this drench solution to cause thicker petioles.
Growth Regulators and Caladiums – general information:            
Growth regulators such as B-9 and Bonzi have proven to be useful for various growers around the country.  Growth regulators do not eliminate the need for good culture.  We believe the best height control for the pot plant trade is achieved by use the proper de-eyeing technique, proper spacing (good light), timely removal from bottom heat and selection of the proper bulb size and variety for the finished pots you are trying to create and use of growth regulators.  In most cases, No. 2 bulbs produce smaller leaves and a somewhat shorter plant.  Of course too much shade will cause stretching.

The following growth regulators have been tried by various growers and research institutes.  Serious caladium growers should conduct similar tests:
Bonzi- Soil Drench 
Apply when plants show a few spikes, and are not yet leafed out at the rate of 8 PPM.  Remember to wait for the first spikes to show since only a well-developed root structure will take up the Bonzi.  The medium needs to be moist, not dry.  Pine bark in the mix will reduce the effect of a Bonzi drench and the concentration will need to be increased by about 50%.  2500 ppm B-9 can be added to this to increase petiole thickness.
Bonzi-Tuber Soak 
Soak tubers for 30 minutes after de-eying in a 8-30 ppm (0.5oz-1oz/gal) Bonzi solution (#3 & #4= 0.25 oz./gal = 8 ppm; #2 & small #1= 0.5 oz./gal = 16 ppm; Large #1, J & M = 1.0 oz./gal = 32 ppm), allow bulbs to dry overnight on the bench and pot them the following day.  This will be effective in reducing the height in cultivars like Aaron, Carolyn Whorton and White Christmas and result in an overall more compact sturdier plant for all varieties.   As always, when using a drench or a soak, the rate depends entirely on your growing conditions.  Growers should experiment to determine the proper rates and exposure for given varieties.
Bonzi – Foliage Spray
 Some growers have found a Bonzi Spray at a concentration of 1oz/gallon or 30 ppm effective in holding plants.  Addition of 2500 ppm B-9 to the Bonzi helps increase petiole thickness and intensifies the colors.
B-9  – Foliar Spray
Rate:  1 pound per 40 gallons of water, 2500 PPM as needed; 5-7 days apart, two or three times when leafed out and spaced.  B-9 also makes for a very sturdy plant and improves colors.  2500 ppm B-9 applied 7-10 days before shipping improves the product at the retailer/consumer level.
Topflor and Piccolo  
Recent (2007/08) studies by North Carolina State University have shown soil drenches of 1-2 mg/ 6” pot to be effective at controlling height in caladiums.  Growers should seriously consider experimenting with these materials. Please Note:  Mention of pesticides, growth regulators etc. are by way of illustration only not an endorsement.  The label is the law therefore growers must follow label directions with all regulated materials.  Furthermore, different cultivars respond differently to treatments therefore try a small percentage of your crop before applying a treatment to the entire crop.  Mention of one product does not preclude the use or benefit of other similar products.  Remember read the label and follow it.