Every year, starting in the fall, I get clusters of emails from frustrated growers experiencing major delays in root formation along with increased failures after having no problems previous times of year. The initial dialogue is frustrating for them because I work through questions relevant to a novice grower before finally realizing they have a condition I'm calling the "fall stall" and has happened to me many times.
The fall stall occurs as temperature drop in the fall, while your mother space is optimized to keeping things cool throughout the warmer summer months. The plants still do 'OK' overall, but are simply not tuned for cloning and produce unpredictable results. Below I offer some symptoms and conditions that indicate your plants are experience this stall.
- Slower growth
- Woodier Growth: new growth becomes less supple and woodier
- Purple striping on the stem.
- Purple/red petioles. This type of purple/red formation should show itself around the whole petiole and on petioles that are not exposed to your lights. I mention this b/c sometimes the upper most petioles will become red on their light-exposed side due to light intensity, and not b/c of ambient temperature drops.
- Darker green leaves that don't lay flat with narrow leaves.
- Root zone temps of <65 F (18 C)
- Ambient temperatures <72 F (22 C)
How to fix the issue:
- Insulate the roots from the floor, particularly for concrete floors.
- Upside-down plant saucers.
- R-max between plant containers and the floor.
- Increase ambient temperature to upper 70's to 80's...Ideally upper 80's. Before adding heaters, try some of the suggestions below:
- Dehumidifiers. dehumidification is often needed in the winter b/c your A/C is cycling less. Dehumidifiers give off heat while removing moisture and filtering your air.
- HPS Lights: if you've switched to some of the more efficient lighting systems (such as LED, CMH, etc) you may consider running some HPS which produce more heat and IR output, while adding light spectrum.
- CO2 Burner are an option, but there are concerns with ethylene and moisture coming from burning propane.
- Space heaters are my last recommendation b/c they are specifically wasting electricity to produce heat.
Why does this happen?
I've often talked about slower cell division at lower temperature and that may be involved, but there seems to be more to it. The change in plant morphology mentioned above mimics symptoms of Potassium and Magnesium deficiency. I was able to find literature suggesting that low root temperature can lockout certain minerals but I have more to learn. For now my focus is helping growers prevent the huge delays in production caused by the slower, woodier, deficient growth I'm calling the "Fall Stall".
If you have any thoughts, please feel free to reach out through our website's contact form.
Thanks for reading and supporting PermaClone!
PS: I'm releasing this post without much editing, so please forgive any typos or poor clarity. You'll see this post evolve as I take time to edit and clarify things. Cheers!