ï»¿This is the first article in a new series where I present some selected tricks and advanced growing techniques. My name is Franco, and i work at Green House Seed Company, in Amsterdam, since the year 2000. Over the last 10 years I have learned from Arjan countless tricks and advanced techniques, and I developed a few of my own as well. And now itâ€™s time to share some of this knowledge with growers worldwide. If we share the knowledge, everybody wins.
This month I explain some of the best tricks to take strong, healthy cuttings, and to speed up the rooting process. These are...
Franco's tricks on cuttings
The most important single factor determining the success in producing healthy cuttings is hygiene. A clean growroom and clean tools are essential to success. In my experience, the best way to keep a mother-room clean is to periodically empty it (take plants out, turn off all equipment) and then spray it with a solution of water peroxide (H2O2 35%) diluted in tap water 1 to 10; this solution can be sprayed over walls, equipment, lamps, pretty much the entire room. After a few hours of ventilation, the lights can be turned on again and the plants put back into place. It is a simple way to kill germs, bacterias, fungi, spores, and any parasites or pests (including their eggs).
This treatment should be done every 4-6 months, depending on the situation. In mother rooms where cuttings are taken regularly, the treatment should be repeated more frequently.
Mother plants have to be in very good shape to guarantee good cuttings. The best mothers are 1 to 6 months old, and in full vigor, under 18 or more hours of light per day. Itâ€™s important to let the mother plants rest between cutting sessions at least 2-3 weeks, to avoid stressing them. Feeding should be applied regularly, but not in the 3-4 days before taking cuttings; the day before taking cuttings, I like to water the mother plants with pH-balanced water (5.5-6.0) containing no feedings, and I make sure the circulation fans are positioned so that the branches keep a slight movement in the breeze, so to keep the cells that form the branches in an agitated and flexible condition; this will help the conversion into root-cells once the cuttings have been taken and rooting hormone applied.
The best time to take cuttings is after a few hours of light exposure, when the bio-processes of the plant are fully active. Air circulation should be reduced to a minimum when taking cuttings, as the dehydration factor is an issue.
I like to use rock-wool as a medium to root cuttings because of the rooting speed and ease to control and flush. 24 hours before starting my cut-session, I like to soak the rock-wool in a solution of water at 24 degrees, with a little Previcur in it (2 to 2.5 ml per liter), a very effective general-purpose fungicide used mostly in the potato-farming industry. This prevents fungi from altering or slowing down the rooting process of cuttings.
When taking cuttings, I try to reduce the time elapsing between the moment the blade cuts and the moment the tissues come in contact with rooting hormone (gel or powder). By keeping this â€œair-timeâ€ the shortest possible, chances of damping-off (death of cuttings by Pythium fungus infection) are reduced to a minimum. To achieve a good rhythm I like to position the mother plant at a good height, so I am able to work fast, taking each cutting, cleaning it from the leaves in excess, then dipping it in the rooting hormone, and directly into the rooting medium. It becomes a very steady and fast motion, and on a good day I can cut up to 210 clones per hour (3 trays of 72 clones).
My favorite tool for taking cuttings is the old-school double-sided razor blade. It is extremely sharp, sterile, and very handy. But it is dangerous, and over the years I have seen several very nasty cuts that needed some stitches to be fixed, so I always advise to have some practice sessions wearing protective gloves before going at it bare-hands (much faster, of course).
After taking the cuttings and labeling them, I place them in a incubator-box, under fluorescent lights. Humidity inside the dome is around 85% for the first 3-4 days, then slowly lowers to 75%, then to 65% for real hardening. I like to harden my cuttings while they are still rooting, because this way the whole process is faster. I believe from experience that cuttings rooted all the way at high humidity are weaker and slower than cuttings rooted and hardened at the same time.
Normally I use Clonex gel as rooting hormone because working with gel is faster, cleaner and less dangerous for the health than working with powder-products (the powders are very fine and highly volatile, and if inhaled are toxic for humans. So, if you use powder-form rooting hormone, wear a mask while working).
My personal record at rooting cuttings is 6 days, but normally the rooting time is between 9 and 14 days, depending on the strain. In order to increase the rooting speed, there are a few tricks that can be implemented. Between them, the most effective are flushing after 3 days with a mild nutrient solution, and using reversed-osmosis purified water to mist cuttings periodically during the first 3 days of the rooting process.
By misting the cuttings with purified water at regular intervals during the first 2-3 days of their rooting process, their vigor is diverted mostly to the production of root-cells. In my experience it is best to avoid feeding the cuttings through the leaves, because this slows root production; if the cuttings get fed through the leaves, there is less need to develop roots to absorb feedings. And by waiting 3 days before flushing the medium with a calibrated solution (5.5 pH and 1.0 EC made with synthetic minerals, ready for intake) the roots will be just shooting out from the cutting when they receive the first stimulus to intake nutrients.
Once the cuttings have roots, I like to plant them in the selected growth medium within 2-3 days; this way the root vigor keeps going, as the roots translate from the rooting medium to the growth medium without stopping against a non-penetrable surface (as it happens when they sit in the tray, already rooted, for days).
Cuttings are the starting point of most crops, and they should be produced aiming at maximum speed and maximum vigor. Timing the cutting session and preparing the logistics for rapid transplanting are the secrets to a fast, healthy production cycle.
Franco â€“ Green House Seed Co.
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