Let Tropical Plants Do the Work for You

Cordyline Kiwi Air Layer tropical plantsA larger segment of the industry outside of Florida has the opportunity to go after new tropical opportunities. All it requires is growers to take the first step to add tropicals, foliage, and houseplants to their production mixes. Capitalizing on the increased demand for tropicals, foliage, and indoor houseplants raises many questions on the best way to include these items in a facility’s current mix, or increase the efficiency of the current space.

There is always a potential to order liners or finished material from places in Florida, but if a grower can fit the production under their own roof, they can often capitalize on higher margins and better control of the quality provided from their nursery. One advantage of working with tropicals is how they lend themselves to being produced as air layers or rooted cuttings by stock farms in Central and South America, thus enabling growers throughout the country to add the unique and exotic items to their mix.

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What’s the Difference Between an Air Layer and a Rooted Cutting?

Air layers are produced on the mother plant. A stem is girdled and wrapped in moist sphagnum peat, covered with plastic wrap, and then aluminum foil. This method stops carbohydrate flow to the roots through the girdled cambium layer, traps moisture on the wound, and protects the area from becoming exceedingly hot in the field, while still allowing the mother stock plant to supply moisture to the foliage via the xylem tissue left intact. This four- to seven-week process results in roots forming and a harvestable air layer that is already hardened off and ready for field production at the domestic grower’s facilities. If the same material had been rooted in a normal propagation area, the time it takes to root the thick-stemmed material may result in damage to the foliage by the large amount of moisture needed to sustain it, or a much smaller sized cutting would be needed to run it through prop.  An air layer provides a durable starter material and a fast turn over time. Both aid in reducing labor and heating costs.

A rooted cutting is what we strive for domestically in our propagation facilities and work extremely hard to do so. However, what if that risk/cost could be outsourced? Tropical rooted cuttings are capable of being shipped after propagation is completed. The starter material is harvested, stuck under mist for three to six weeks, partially rooted, and shipped extremely densely to the customer. Taking advantage of these characteristics of tropicals is extremely beneficial to control many costs in the growing process and providing your farm with an advantage compared with standard practice of rooting unrooted cuttings (URC)

Tropical, foliage, and houseplant items ship extremely well due to their relatively high resistance to ethylene damage, disease development, nutritional depletion, relative humidity exposure, and temperature swings in shipping, especially when you compare them to most annuals that cannot tolerate these obstacles of shipping to the same extremes. In addition, where many annuals, if rooted, would have their thin, fibrous roots desiccate during shipping, the roots of many tropicals are somewhat succulent and robust, making them perfect for a short trip across the world.

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Advantages of Air Layers/Rooted Cuttings Versus Liners

  • Cost per unit is normally more than 50% less expensive with an air layer (AL)/rooted cuttings (RC) than with a liner.
    • No soil, No plastic tray, No domestic labor
  • Cost of shipping is more than 50% less with an AL/RC than with a liner
    • AL’s/RC’s are boxed much denser than liners, increasing the quantity of units/box
    • Example: Box of 8-inch rooted cuttings of croton=300units/box    6-inch Croton Petra 72 cp liners  =144units/box
  • Constancy is superior with AL’s/RC’s compared with liners:
    • With liners of Schefflera, Crotons, Cordyline fruiticosa, etc., rooting is unknown to supplier and customer until transplant, with up to 10% not having roots.
    • AL’s/RC’s are 100% rooted because they are shipped naked, outside a cell pack after a 1-by-1 grading at the stock farm prior to shipping
      • They receive two gradings once while being harvested for length/leaf count/stem diameter and again at packing for root development.
    • Size available as AL’s/RC’s can be much larger than liners:
      • RC/AL’s are often larger because they are packed horizontally where liners are stacked vertically in the shipping boxes.

Advantages of Rooted Air Layers/Rooted Cuttings vs. Unrooted Cuttings

  • Risk mitigation is significantly reduced with AL’s/RC’s when compared with URC’s.
    • URC’s are rooted overseas to create RC’s. Any losses stay there, so risk of loss is reduced for your farm
  • Labor Savings can be gained with AL’s/RC’s over URC’s.
    • AL’s/RC’s can be directly stuck into their final container, which is far less labor than sticking cuttings and then transplanting liners later.
  • AL’s/RC’s shorten grow times and increase crop turns compared with URC’s.
    • AL’s/RC’s save on average a month of grow time on the recipient’s property, increasing the speed at which a crop is turned over and placed on availability
  • AL’s/RC’s are just easier:
    • Not only is a sophisticated propagation space not required for RC/AL’s, but the fine art of propagation is also not needed, thus increasing the success rate and shortening the learning curve with this type of material.
  • Less space in prop.
    • Skip propagation. It’s done.

Plan Ahead for Ordering

When ordering AL’s/RC’s, keep in mind that the stock farms need to be aware approximately six weeks in advance to root the material. Additionally, while this cannot be done with every tropical option, note that the following popular items do allow for rooting at the stock farms:

  • Crotons
  • Dracaena
  • Cordyline
  • Aglaonema
  • Schefflera
  • Dianella
  • Bromeliads
  • Pepperomias
  • And several others.

 The general process of working with RC’s and AL’s is:

  • Direct stick into final pot
  • The first two weeks: heavy shade, super high humidity, constantly moist soil
  • Week 3 and 4: heavy shade, slightly lower humidity, and begin cycling soil moisture as roots expand into media
  • Week 4: increase light, reduce relative humidty to 50%, and continue cycling soil moisture
  • Grow on.

 Let’s Take a Deeper-Dive Into Production With Air Layers and Rooted Cuttings

Ideal conditions to establish AL/RC:

1,000-2,000 footcandles (fc)  = Heavy shade: In Texas, three layers of 30% or simply one layer of 90% shade when the house has no plastic in the summer; 60% shade or one to two layers of shade with plastic is good as well. The plastic helps keep the humidity up and allows for a little higher light during prop.

Time line: Avoid stress in the first 72 hours (most susceptible time). Plant in a well-drained media but maintain this media evenly moist for the first two weeks. Keep the humidity high during this time as well, avoiding wilt while roots expand. Reduce humidity and, if possible, eliminate overhead irrigation by day 14 or as soon as the crop allows you to start to back down (if earlier — great)

Do not overhead irrigate on rainy days. Roots should expand on more than 90% of the crop by the end of week two.  (Summer tip: Receive these from the airport Monday morning and keep below 72⁰F or in the office in the boxes. Plant in the evening. If employees can start late and leave late that helps as well. This helps avoid the first day’s mid-day heat stress. Watch the crop on day two and adjust humidity with a quick overhead irrigation accordingly to prevent wilt.)

Leave in the same shade for two weeks more to finish expanding rooting on all 100%. Week four remove one layer of shade. Always prevent wilt when the environment changes. Removing shade late in the day and wetting foliage once to help with the transition is beneficial to prevent stress from the environmental change. Heavy wilt during this stage will cause leaf drop. High humidity or high temperatures are better than low humidity and cool temperatures.  Air flow is not needed during the first three weeks, but foliage should not have free water on them for hours on end (or going into the night).

Once rooted, growing the material in 4000 to 6000 fc (or 30% shade) with humidity above 50% is ideal. Push by thoroughly watering soil and allowing to partially dry between waterings. Keep foliage dry at this point. Feed with a slightly higher ammonium feed like an 17-5-15 at 150 to 200 ppm regularly.

Once to full size, pull the shade and expose to full sun to delay growth and promote coloration (This is not required on all items but is a good trick on some). 

Four Practices to Incorporate Into Production

  1. Prevent RC’s/AL’s from dancing: Frequent overhead mist or irrigation over a pot with a RC/AL spaced apart in the final container will allow them to dance or move. If they dance and widen their hole, they will not continue to root out, or the crop will root unevenly. Prevent this by planting deep enough to steady the URC but do not enough to bury a node. Have employees firmly close soil around planted RC’s/AL’s and plant into already moist soil to help with this.
  2. Take caution with slow release in the media: Ensure any slow release in the growing media will not dump feed while the media is being maintained at very moist levels. This will oxidize and burn the roots, causing them to turn brown and root unevenly. Monitor electrical conductivity (EC) occasionally with the pour-through method and leach when EC exceeds 1.25mS/cm. Consider a low level of slow release incorporated or rely on soluble feed in the line during establishment, and top dress after four weeks once roots have expanded.
  3. Prevent wilting: Do not allow the crop to wilt. In a liner tray, the material is kept at a tighter density and maintaining the correct humidity to prevent wilt is easier when these are packed like sardines. When direct sticking material, prevent wilting by turning off horizontal airflow (HAF) during establishment, keeping doors shut, and moving product away from doors/ventilation and fans/vents. Hanging remay/cheese cloth over the crop using bamboo stakes greatly helps with maintaining a high relative humidity or start them in a low ceiling greenhouse such as a hoop house where humidity can be quickly banked and maintained. During the heat of the day, vent occasionally from 12:00 p.m. to 3 p.m., if needed, to evacuate heat by using vents higher than plant level. Water the foliage and floors to lower the temperature and replace humidity before and after purging the house. Temps of 95⁰F or higher do not help with establishment but can be tolerated for short periods of time. Do not rest remay directly on plants, as they will dance and the foliage will stay too wet.
  4. Grade Your Plants: If you see some plants taking off (normally in week four or five), make any consolidations right away before the roots interlock within the pot. This is rarely an issue with air layered and rooted cuttings, but a check (and trouble shoot), if needed, should occur by week five to keep the crop on track.

Direct sticking is a common practice with air layered and rooted material but these are the main obstacles to avoid.

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