Auto Flower Perpetual Redundancy Part 3

Week 3 Update These girls are about to take off with their stretch starting soon. Just incredible growth not just on top but even the root system must be very good since I needed to water to run off at the end of the week. My run off was 1100 to 1200 ppm with a ph of 6.3. This is the first grow where the plants have already needed to be watered to runoff by week 3. Usually end of week 4 beginning of week 5 has been the standard for my auto grows. I think these may be heavy drinkers/feeders we will see. Holding off on nutes until I see some fade in the single and 3 point oldest lower leaves. TIP OF THE WEEK Please feel free PM me for questions about the Hydrofarm PAR Meter or recommendations for brands. AUTO FLOWER LED LIGHT INTENSITY I’m trying to keep things here as simple as possible. Forget about Lux and Lumens they serve little or no purpose in growing plants. These terms are meant for light spectrums visible to the human eye not plants. The following terms are really what we want to be dealing with when trying to purchase or calculate lighting for our grows. PAR (PHOTOSYNTHETICALLY ACTIVE RADIATION) Photosynthetically Active Radiation is the spectral range (wave band) of light radiation from 400 nm (Blue) to 700nm (Red)wavelength. Plants use light within this range for the process of photosynthesis. So PAR is basically the amount of light in the 400 - 700 nm color spectrum that can “actually” be used by the plant. PAR does not measure the amount of UVA or UVB and Infrared that plays a part in trichome formation and cell quality. Some manufacturers have meters which can measure further into the infrared and far-red spectrum which may not be entirely necessary. PPF measures the total amount of PAR emitted from the lighting system per second. Most common unit is μmol/second. μmol are also known as (Micro Moles). PPFD (PHOTOSYNTHETIC PHOTON FLUX DENSITY) PPFD is a measurement of the amount of Photosynthetic Photon Flux per unit area. Its number of photosynthetically active photons that fall on a given surface each second”. PPFD is measured at a specific position of plant canopy and is measured in micro moles per square meter per second or μmol/m2/s. For the purpose of simplicity, I will just use the term umol when discussing PAR meter readings. DAILY LIGHT INTEGRAL (DLI) Daily Light Integral (DLI) is the total number of photosynthetically active radiation (PAR) photons (traditionally those between 400-700 nm) incident on an area over the course of a day. DLI is a function of both the intensity and duration of the photosynthetic light falling on the target over a day and is most commonly expressed as moles of light per square meter per day. For the purpose of simplicity, I will just use the term moles when discussing DLI amounts per day. Using a PAR meter and calculating DLI is the only way to properly measure how much of this lighting spectrum and its intensity you are exposing your plants to on daily basis during key phases of growth and bloom. If not, you are just guessing and risk damaging your plants and precious buds. Our goal is to have a “minimum” DLI in the 38-40 moles range when in bloom. Extreme care should be used when approaching a DLI of 60 moles or higher. Using a DLI of 65 moles is typically the maximum high light intensity/duration cannabis plants can handle per day and it is extremely risky to expose them to this much light therefore it is not recommended. In reality a light intensity of this nature would be if you lived at the equator during mid-summer on a crystal-clear day when the sun is at its highest intensity possibly on a mountain side. Growers who prefer Photoperiod plants can actually run their intensities at a higher level because they are only running their lights 12 hours a day while in bloom. At 12 hours per day in order to meet the minimum DLI required for bloom running the intensity at 900 umol (DLI 38.80) works well and running the intensity at 1200 umol (51.84) during late bloom is a safe maximum. You can possibly run at a higher intensity with the use of supplemental Co2. Keep in mind that these are estimates and each plant or strain may be able to handle more or less light. Other considerations like temperature, humidity and Co2 concentration should be taken into account. Finally, the moment we have all been waiting for! Why is getting the light intensity and spectrum so important when growing Cannabis? It's actually very simple, light intensity and spectrum triggers your plants natural defense to protect themselves from the intense and possibly damaging light by producing more trichomes which is exactly what we want. Giving them the right spectrum and intensity during each stage of growth and bloom will yield some of the finest quality bud we all know and love. I personally use the following as a guide when growing Auto Flower strains. Recommended LED PPFD/PAR Values / DLI Based on 20 hrs. of light. Seedlings 150 - 200 umol / DLI 10.80 - 14.4 moles per day Veg up to 9" 450 umol / DLI 32.40 moles per day Early bloom 500 umol / DLI 36.00 moles per day Mid bloom 650 umol / DLI 46.80 moles per day Late bloom 750 umol / DLI 54.00 moles per day Ripen 400 umol / DLI 28.80 moles per day (Ripen is the last 7 to 10 days before harvest.) *** Use extreme caution going 700 umol or higher @ 20 hrs./day this could cause leaf burn*** I’ve included some links for more in-depth information and a nice calculator for assessing your lighting needs. https://www.apogeeinstruments.com/determining-grow-light-position-using-a-par-meter/ https://www.apogeeinstruments.com/daily-light-integral-measurement/ https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator https://horticulturelightinggroup.com/blogs/news/horticulture-metrics-par-ppf-ppfd-dli https://www.waveformlighting.com/horticulture/what-is-the-difference-between-ppfd-and-ppf