This article is about those methods that produce clones covered with roots from collars to cut…and with no loss of growth potential or yellowing above the collars. As always, I keep efficiency and scaled production in mind!
In cloning, warmer temperature speed cell divisions with diminishing returns at 87 °F (30 °C). However, this also speeds growth of bacteria and fungi. Before attempting higher temps, get sterile! Deep Water Culture (DWC) is different than aeroponics. With DWC the goal is the best temps for both oxygenation AND root growth. The convention is currently 65 – 68 °F. We believe this temperature recommendation may increase as techniques improve for effective water treatment.
Use an IR Thermometer or permanently placed temperature meter to quickly measure water temperatures. This is fast while preventing contamination of your cloner. We have found external IR readings to be within 0 – 2 degrees below the actual internal temperature and this range depends on the ambient room temperature. For example, if your ambient temperature is 75 °F and your cloner is at 85 °F (29 °C), you IR reading may be 83 °F (28 °C). Alternatively, if your ambient temperature is 75 °F and your cloner is at 77 °F, your IR reading will be relatively precise.
More Nodes & Shoot Apices
Every shoot apex produces auxins (rooting hormones). The more nodes left untrimmed from your cutting, the more endogenous (natural) auxins will be produced and sent to the basal (bottom) end of cuttings. The goal is 3 – 6 nodes left uncut. You may remove the fan leaves to avoid shading other clones but this is not necessary with aeroponics, DWC or bubbleponic cloning.
Cutting fan leaves has traditionally been intended to decrease transpiration, but that’s not a concern in aeroponics. We recommend trimming leaves to avoid shading other clones OR if your source plants are over-fed nutrients with dark green leaves. Below we discuss how to maintain mother plants for effective cloning. Leaves will help generate the carbohydrates needed for prolific rooting.
The common suggestion has been minimal lighting. People often place a single T5 1 – 2 feet above the cloner canopy. This was because plugs couldn’t hydrate the cuts enough to prevent wilting. This is not the case with hydroponics cloning. Over time we noticed shaded clones rooted slowest or failed. We ramped up lighting to 4 bulb T5 flourescent fixtures at 4” from our cloners’ canopies and achieved significant improvements in cloning rates, speed, AND root mass. This is particularly important when taking multiple clones per collar. We currently recommend 4 – 8 bulb T5 fixtures 4” from the canopy with mixed blue and red spectrum bulbs.
Adding 1/4 -1/2 strength bloom nutrients (200–600 ppm or EC: 0.4–1.2) to the cloner improves rooting both in speed and volume. We recommend nutrients intended for water culture. Avoid products which will inoculate or feed bacteria and fungi such as amino acids, protein hydrolysates, sugars, carbohydrates, or ‘teas’. Do not add beneficial bacteria or fungi. We suspect there may be a bacteria or fungi for aeroponics, but have yet to demonstrate strains of interest for long-term effectiveness.
Auxins improve rooting time and root volume. Gels and powders wash off and are time-consuming to apply. We have found efficiency in water soluble hormones such as Hormex Liquid Concentrate, Rhizopon AA, and KLN Rooting Concentrate. Each ensure adequate exposure times and eliminate the workload. We have worked mostly with Hormex Liquid Concentrate at 3 – 6 mL/gal. These product do not contain minerals. It is important you include a mineral nutrient in concert with hormone products for maximum performance. Do not use hormones without mineral nutrients, the results are NOT the same.
Pump Cycle Times
Cycle timing is primarily used for temperature management. Through extensive testing we have found faster rooting at warmer temperatures with diminishing returns above 87 °F (30 °C). We suggest 75 °F – 85 °F (24 – 29 °C)
Callus or Callous is non-specific plant tissue that can become many different cell types depending on environmental factors or plant growth regulators. If you achieve extensive callusing, but roots lag, cycle your pump 15 min ON/45-60 min OFF for 24 – 48 hours or until 2 – 3 mm of roots form. Then set your cycle time to that which achieves the ideal temperatures. Over-callousing would indicate the need to lower hormone dosage for that particular strain.
If you’re using a DWC cloner and achieve extensive callous growth, change the water to mineral nutrient alone and eliminate the hormone product. Likely the hormone is pushing callous production and preventing root initiation from this non-differentiated tissue. In this situation, consider lowering your dosage to avoid the extra work of changing the water.
Feed mother plants low strength bloom nutrients (TDS: 300 – 400 ppm; EC: 0.6 – 0.8 mS of base nutrients) while maintaining normal doses of Calcium, Magnesium, silicate, and kelp extracts. Aim for a total TDS of 500 – 600 ppm on the 500 scale (i.e. EC 1.0 – 1.2 mS) with additives. The goal is to minimize nitrogen to just above deficiency levels while maintaining all other nutrients and endogenous auxins (rooting) hormones. Lower nitrogen induces increased carbohydrate storage in the stem of mother plants. Silicon nutrients (such as silicic acid or potassium silicate) have been correlated with improved root mass in cuttings when applied to mother plants. There are points of antagonism, so use the intermediate recommended dosage of silicates.
Foliar applications of kelp-based products the day before taking cutting improves auxin levels within the plant (systemically) and improve rooting speed and volume. Auxins travel fast within plants, but do require several hours to be distributed systemically. We recommend applying 24 hours before taking cuttings.
Source: Permaclone, (https://www.permaclone.com)