SCIENCE & OG NOTES + sources

latest content update: Sep 4, 12022


BRIEF

  • this is what I use to organize my notes - I wanted to share it.

  • this is a work in progress and if you want to chip in with your own information, please do so.

  • this is my journal.

  • The notes are divided as follows:
    A. ON BOTANY
    B. ON PRE-PLANNING (genetics, par light, envir, method & medium, and fertilization)
    C. ON GROWING (techs, veg, flower, harvest, cure, issues and pest mgmt)
    D. ON POST PROCESSING (decarb, edibles, hash and other concentrates)
    E. ON INTERESTING GROW JOURNALS AND CONTENT IN OG


A. ON BOTANY

Cannabis is a vascular plant - specifically, a flowering herb. Vascular or higher plants have lignified tissues (the xylem) for conducting water and minerals throughout the plant, and a specialized non-lignified tissue (the phloem) to conduct products of photosynthesis (mainly glucose + oxygen).

B. ON PRE-PLANNING

In Priority

  1. Genetics
  2. PAR Light
  3. Environment
  4. Medium (Water & Air) and Fertilization

I. GENETICS

Genetics will be responsible for the general quality of your grow (whereas your growing method will correlate closely with maximizing yield and potential of that plant).

Dedicated Breeder/Genetic Threads in OG

Find reliable seed banks

More info

II. LIGHT

This only applies to LED. I do not research HPS.

PAR light and Spectrum

PAR means photosynthetically active radiation. PAR designates the spectral range (wave band) of solar radiation that photosynthetic organisms are able to use in the process of photosynthesis - in other words, the specific light spectrum (specific wavelengths) that cannabis will use for photosynthesis.

Solar light has a spectrum of 300nm to 800mm. Of that range, it is usually considered that PAR light falls between 400nm (blue) to 700nm (red), yet there are studies that indicate that some ultra violet (UVA 315-400 nm) and far red (700 - 800nm) light affect trichome production and photosynthesis.

Efficiency VS Spectrum

According to research by Dr. Bruce Bugbee from the Utah State University, roughly speaking - if everything else is stable, the amount of light provided will dictate the quantity of your yield. Efficiency (micro-mol per joule) will generally be more important than spectrum when it comes to yield. Choosing an efficient light is essential.

It is important that the LED manufacturer is straight forward regarding the real wattage and efficiency of the light, the diodes it uses, and the spectrum.

III. ENVIRONMENT

Making sure you are able to maintain the proper environment is important because it will determine how much you can push your plant (how much CO2 it can take, how much you can water, feed, and not stress it).

Humidity & Temperature

Marijuana takes water and air from its roots, and transpire it through its leaves. If transpiration rate is too fast or too slow, it will cause issues with nutrient uptake, root rot, mold, etc.

VPD charts (above in links) will help you understand the right temperature and humidity ratio to maintain correct transpiration rates in its different stages.

Air Circulation

It is very important to ensure plenty of air circulation to provide enough CO2, control temperature, prevent humidity issues, as well as preventing pests and mold. Having an air vent (like an inline fan) and small fans is a must.

IV. MEDIUM & FERTILIZATION

Soil-less

Soil

General

Metods & Medium

The different growing mediums/methods - let it be soil, coco coir, peat, deep water culture, aeroponics, etc - are just creative solutions to balance the plant’s water and air necessities. Essentially, the challenge is how to provide the plant with as much water as it can take without drowning it and how to provide the plant with as much air as it can take, without drying it.

There are two main school of thoughts regarding mediums: soil and soiless. While you can have Soil Inorganic and Organic, as well as Soilless Organic and Inorganic, this guide will only deal with Soil Organic (although “organic” is a debated term) and Soiless Inorganic.

See links for specific medium recipes.

Soiless Inorganic

The two extreme sides to balancing water and air are best exemplified by

  1. having the roots partially submerged in highly oxygenated water (for ex, DWC - a bucket with water and an air pump) or
  2. having the roots suspended in air with constant water misters (like an aeroponic setup),

The problem with extreme soiless methods like DWC and aeroponics is that they depend on the grower knowing exactly what they are doing (and having reliable power sources and good budgeting) since being in extremes means having little room for error. Peat and Coco Coir mixed with Perlite or very coarse vermiculite for aeration are great soiless solutions that will allow you to have a little more wiggle room.

In soiless inorganic all the nutrients are directly provided by the grower through fertilizers diluted in water and/or dry amendments, in the form of inorganic chemicals (the plant takes the element ions the same way regardless its source).

Water PH for soiless mediums should be kept within 5.5 to 6.5, with many growers finding best results at 5.7 to 6.0 ph.

Soiless Inorganic - Fertilization

Cannabis needs a balanced nutrient regimen of primary nutrients: Nitrogen, Phosphorus and Potassium (NPK); Secondary nutrients: Calcium, Magnesium, Silica; and Tertiary nutrients: Iron, Boron, Manganese, Zinc, Copper, Chlorine.

You can get a 20-10-20 or similar dry fertilizer (that you’ll need to dissolve in water) and apply it through out the grow (with minimal adjustments between veg and flower) for 90% less of the price you pay for a cannabis marketed products (specially liquid ones). Check the links of this section for specifics.

Optimal fertilizer ratios according to Utah University Research (Thanks to @Davesnothere)

For veg: (these are all mg/L). N- 120, P- 30, K- 129, Ca- 50, Mg- 17, S- 21, Si- 8, Fe- 1, B- 0.40, Mn- 0.32, Zn- 0.32, Cu- 1, Cl- 1, Mo- 0.06. For flower you can increase the P up to 50mg/L with monopotassium phosphate or other similar “DIY bloomers”.

You can look for these raw fertilizers

Soiless Inorganic - Fertilization - PPM

PPM or parts per million is the number of dimensionless parts multiplied by a million. So for example, 1 ppm is like 1 minute in 2 years (if you see how many minutes are in a year it is roughly a million). To better understand PPM in terms of nutrient and water, you can express it like milligrams per liter (mg/L - because there are 1,000,000mg in a Liter), therefore 1ppm of Phosphorous, means 1mg of phosphorus per liter. In general PPM will be how much nutrient you are giving to the plant.

When you look at feeding guides you will see that many refer to EC or PPM. These are not really that translatable, but there are charts to convert (see links)

In fertigation (meaning you dissolve most or all of your nutrients in water) how much PPM you give your plant will heavily depend on CO2 levels, VPD consistency, genetics, medium, and plant health. As a general rule you can apply a 1.3 EC or 650 ppm through out the grow.

Soil Organic

In soil organic the grower provides nutrients indirectly to the plant by feeding the microbiology sustained in the soil. Those microbes in the soil will process the organic matter (eat and poop it) and produce the element ions that the plants will use as food.

Soil organic has the widest margin of error as it is harder (but no impossible) to break the plants thresholds for nutrients. While there is a widely accepted idea that ph in soil is not important, the actual ph of the soil (not of the water like in soiless) is important for its impact on nutrient availability and Cation Exchange Capacity of the soil.

Soil PH should be usually kept at 7 or slightly acidic.

Soil Organic - Fertilization

In the above links (at the start of IV. MEDIUM & FERTILIZATION) you will find many soil recipes to maintain good fertilization. When you keep a healthy aerated soil, watering and knowing when to water is probably the only things you need to worry about.

Watering

For Soiless Coco

For best results water should be kept on a constant basis with automatic fertigation tools or by watering daily (depending on size).

For Soil (and Peat soiless growers)

Fill a same-size container with barely dry (soil) or barely moist (in case of coco and peat) and lift it to have a reference of how much that container weighs when its about to dry, then fill it with water and feel how much it weighs filled. Water everytime the pot gets close to the dry/barely moist weight.


C. ON GROWING

I. Techniques

General

Pruning

Training

Propagating

II. Germination

The two main schools of thought regarding germination are: with pre-germination and without pre-germination.

note: when using peat make sure it has dolomite or amended to raise ph.
note 2: when in peat or soil make sure to have enough perlite/vermiculite or soil conditioner to ensure air and fluffiness - critical for seed and seedling health and avoid damp off.

III. Seedling

Light cycle in Seedling is predominantly lighted, meaning your lights should be anywhere from 18 to 24 hours on and 6 to 0 hours off (it is recommended to start with 18/4) if your plants get too stressed (if droop towards the end of the light cycle, then lower intensity or cut down on hours with lights on)

Temperature and Humidity will have to follow a .4 to .8 VPD. Regardless of VPD, 70% humidity is recommended during seedling stage.

In this stage, the seed sprouts and grows a few inches along with cotyledons (the first leaves). The cotyledons store nutrients and help supply the seedling with its initial nutrition.

Transplanting

IV. Veg

Light cycle in Veg is predominantly lighted, meaning your lights should be anywhere from 18 to 24 hours on and 6 to 0 hours off (it is recommended to start with 18/4) if your plants get too stressed (if droop towards the end of the light cycle, then lower intensity or cut down on hours with lights on)

Temperature and Humidity will have to follow a .4 to .8 VPD in the first 7 weeks and .8 to 1.2 VPD in the last weeks.

It is also recommended to apply neem oil once a week during veg to avoid common and frequent pests like spider mites (neem oil should be discontinued in flowering)

Light leaks in veg has been hard to investigate, general consensus seems to point towards “not that important, but fix them before flowering”.

V. Flowering

With Autoflowers they will go into flowering on their own, on average within a month of being sowed. Although it is not uncommon for some to take more.

Photoperiods will change to flowering when you change the cycle from mostly light to 12/12.

The first three weeks of flowering are usually known for stretching, meaning plants will grow up to double their size. Later weeks will see bud growth, change in color of pistils (the white “hairs” that grow from the buds), and trichomes will become more prevalent and grow (trichomes are the structures that contain the cannabinoids and terpenes)

Temperature and Humidity will have to follow a .8 to 1.2 VPD in the first 7 weeks and 1.2 to 1.6 VPD in the last weeks. Regardless of VPD, it is recommended to keep humidity in the 45% to 58% range to avoid issues with mold, fungus, and bud rot.

Light leaks in flowering are known to cause stress, producing nanners and other hermaphroditic characteristics, and even reveg (force your plant to go back to vegetative state).

VI. Harvesting

Usually, people suggest that when 20 - 50 % of trichomes are amber (you check that with a 30/60x loupe), you can consider harvesting. Equally important is to look at the pistils, they should be brown in color and receded to closely to the bud (meaning they are no longer extending away from the plant, but have actually contracted towards the bud).

Washing

Many users wash their flowers before they hang them to dry. A pre-trim may be performed, but it is not necessary. The process consists in dipping the freshly cut harvest into three or two (depending on method) buckets.

The simplest version is to dip the flowers for 1 or 2 minutes in a 5 gallon bucket of water with 250ml of 3% H202 (Hydrogen Peroxide) - or 75ml of 34% food grade H202 in the 5 gallon buck of water - and then dip into a second bucket filled with simple water for rinse, then let drip dry (preferably with a fan near)

VII. Drying and Curing

Drying and curing science is VERY limited. Water Activity is the key factor, but the problem is measuring water activity (expensive equipment). So unless you have a good water activity meter, you’ ll have to go with humidity as your reference.

After chopping (or if you washed them, after initial soak has dried) hang on a dark room or diy drying box and make sure humidity is set to the lowest possible (if controlled) or leave at the driest dark room available for the first 24 hours, after the first 24 hours try to get humidity on a 55% - 60% range and temperature on 70F (max) for about 10 days, or until stems snap or almost snap when bent.

After drying, put into glass jars 3/4 full with a small hygrometer, and check that humidity does not rise above 60% inside the jars. To help maintain 60% or lower humidity, jar burping is necessary (opening the jars for 30 minutes in a cool dark place).

Nagel420 has a great auto burping system

to know more about the limited science on Drying and Curing please see:

VIII. Issues and Counter-Measures

There are many issues (deficiencies, toxicites, pests, and environmental). In order of importance:

  • IPM (Integrated Pest Management) DONT fuck around with pests. Have an IPM ALWAYS. Any IPM system will include (i) frequently cleaning and disinfecting grow spaces with h202, iso alcohol, and/or heat treatments (like steamers for ppl on budget); (ii) cleaning and disinfecting tools used in pruning and cloning; (iii) setting rules like quarantining plants, or not taking clones.

  • when it comes to prevention Neem Oil (with MINIMUM or NO SOAP, soap will burn your plants) and Spinosad is OK until the end of first week after flip.

  • When it comes to prevention and control (meaning you have bugs already) Abamectin (Avid), bifenazate (Floramite), spiromesifen (Forbid) are kings/queens. Use until first week of flower. Abamectin can be considered organic.

Deficiendies/Toxicites & Environment

When it comes to deficiencies and toxicities, its important to understand that a wrong ph, far off VPD, and even overdosage of a certain nutrient can cause the deficiency of a different nutrient, making diagnosing a pain (you may see a certain deficiency and try to give the plant more of it, not knowing that the levels are actually correct while it is ph, VPD, or a toxicity that needs to be fixed)

Its important to get VPD right with planned EC and proper PH, to be able to single out irregularites, and try one thing at a time.

RED FLAGS

  • Taco shaped leaves
  • Droopy, wilting or curled down firm leaves
  • Droopy, wilting or weak-limp leaves
  • Clawing leaves (leaf tips pointing down)
  • Yellow leaves
  • Brown leaves
  • Red Stems
  • Brown & yellow leaves
  • Dark green leaves
  • “Burnt” leaf tips
  • Twisting

Based on the above-mentioned RED FLAGS, diagnose your plants:


D. ON POST-PROCESSING

i. Edibles

ii. Concentrates

E. ON INTERESTING GROW JOURNALS AND CONTENT IN OG

Grow Journals

  • Motaco - For those interested in heirloom and heirloom mix breeding.

  • Mr. Sparkle - Clean, organized, detailed.

  • Mr Sparkle - Micro-grow

  • ReikoX - Advanced, technical, clean, detailed, Organic. - Soil Tests!

  • 99PerCent - Beautiful greenhouse.

  • GramTorino - Very detailed (with lots of good + explanatory images), clean, and organized.

  • Ttystikk - Vertical farming, say no more.

  • Eskobar’s - Crop Steering and Strain Judging in Mapito Flood Tek

  • Lotus70 - No Till Korean Natural Farming

Informational Sources

Heirloom Threads

Off Topic Threads

60 Likes

great post, thanks for sharing your compiled sources.

5 Likes

Interesting, many thanks for gathering all the data.

1 Like

Still needs a lot of work, specially in the last sections, but I fill it as I go along with my first grow and I intend to keep updating even after. Thanks!

6 Likes

Not sure what is okay on off site links, would think Overgrow would want those links to be to sponsors pages if they have that info. I understand some are pretty awesome.

Thanks for the correction!

I tried looking at New to OG? How to use the site? Tips, tricks ✨
to see if there was any specifics to offsite links. I didnt see anything rigid like other forums, and I´ve seen other threads promote some of these links or similar links. so I thought it would be OK. But Id remove anything the mods ask me to. I tried to keep most of it with inside (OG) links.

1 Like

Nice work ^5

1 Like

I didn’t review all of the links in the OP though we are not overly concerned with off-site linking. OG is a platform for dissemination and we also know that we do not operate in a vacuum.

The overall knowledge base is way too broad in breadth to have it all or, for that matter, to be the best resource across all concerns. There are folks pushing on the boundaries based on differing opinions, new science, techniques, and technologies that are running on other platforms. While it would be nice to be able to link to as much as possible right here, it’s simply not realistic. The breadth is wide and expanding.

Where the problems generally come in is with affiliate linking, engaging in promotional efforts, or linking to inappropriate sites that conflict with the TOS and FAQs. E.g. marketing, sales, profit generation, shilling, etc.

10 Likes

Really nice job compiling pertinent information for the first time growers. Maybe Joe can sticky it.

1 Like

FYI I usually send my new-grower friends here - another good resource

7 Likes

Thanks!

I still have a lot of work to do on it, including cleaning up links. Right now my focus will be to summarize more info, specially on the last sections, and focus as much as possible on content already on OG, and whatever I cant find here Ill link outside.

Let me know if you find anything that wont fly.

I really appreciate OG, its vibe, and content. - hopefully this helps the new members like me.

3 Likes

I think theres still lots of work to do, hopefully I will have a better version within a month.

1 Like

thanks! got some links from growweedeasy actually in there :slight_smile:

1 Like

Excellent! I have a ton of notes like this as well but no where near to this level of organization. Thanks for sharing!

2 Likes

I would think that would be a lot for a newbie… learn how to grow it first before making seeds. I think you need to slow down

3 Likes

hi! I dont recall the guide having anything to breed or pollinate - other than superficial info to just understand what certain terminology means (like S1 etc, for when buying seeds etc). - which part are you referring to?

but yeah, im nowhere near making seeds (im overwhelmed just by growing :slight_smile: )

2 Likes

Very cool, thanks for sharing…

1 Like

Yah I’m not a noob but now my eyes and brain hurties, I send noobs to growweedeasy also

2 Likes

Thanks naturalselection that must have taken some time and patience.
Groweeedeasy taught me alot too.

1 Like

if you have the time, you can paste them as a reply and ill go through them and sort them out, always appreciated.