Heres what I would do. YMMV.
#1 I agree it could be the strain.
#2. I would use a strain that has strong side branching, stretches a good bit a flip, and I would BEND THEM, vs Topping them, and train all of the side branching to grow Vertically. This opens up the whole plant, and IMHO, if the strain is nice and branchy, if you top it ect, all youre doing is slowing it down. IMHO/YMMV.
When you cut that Main Tip, you are greatly decreasing/slowing Vertical Growth... Lateral if you are bending them, and training them to grow Laterally vs Vertical.
Bending has basically the same affect as topping them, but you don't muck with the tip, and halt upward progression.
I don't mess with the tip, unless Im trying to slow growth. I bend starting at 20% to 1/3rd of the way down the plant, and I start training very early. Month, or less. If they start developing good side branching early on, I start training them then. By not concentrating on the tip, I keep the growth going quickly, adding side branching, that is really growing Vertically, as it lengthens.
You have to pull the small secondaries around the Main Stem, to make them grow Upwards/Vertically, and make the main tip grow Horizontally
I want the plant close to growing at 10-25 degree angle degrees Vertically, and train all the side branching to Major Branches. I also Shake my plant, and slightly Pull them a bit by the main stalk, and also bend around a bit on the secondaries to make them stronger. But after they are doing what you want, you don't have to mess with them anymore.
#4.. Id go to 20 Gallon containers... What is your soil Mix???
For Medium to use with chemicals... I like either Promix BX, or Promix HP. The BX holds a bit more water, and HP is lighter, and has to be watered a bit more often. I use the BX. Both work.
I also add 34 LEVEL TSP of Calcitic Lime, and 17 LEVEL TSP DOLOMITE LIME per 3.8 cu/ft Bail Promix BX.
#5. Id ditch that fertilizer. Their formula is not specific enough, and from what I can tell is not optimum for marijuana.
Going by Tissue Analysis, and from a company that has been making PLANT SPECIFIC FERTILIZER since the 70s, ( CHEM GRO ) says the optimum formula is
19.5 x 20 x 39. With increasing needs for Magnesium, P/K/Nitrogen at certain stages. For an 8 weeks strain they need more Mono P/K at weeks 3/4, and Increasing needs for Magnesium until week 6, but still is only backed off a small amount. Same for Nitrogen. Increasing Need.
FAKE NEWS WEED HAS LESS NEED FOR NITROGEN IN FLOWERING. IT NEEDS MORE OF EVERYTHING.
Weed likes 2x the amount of Potassium vs Nitrogen, and only slightly more Phosphorous vs Nitrogen.
Its also a MYTH that you need to reduce Nitrogen in Flowering, and is Illogical.
While it is true you can muck them up with TO MUCH Nitrogen, it is Critical in bud formation, and growth/stretch during flowering.
In a Human Being when we Eat Protein our bodies turn this into... NITROGEN, and keeps us in an Anabolic condition. AKA Positive Nitrogen Balance... If you are Low on Nitrogen, ( Catabolic ) you will use your own muscle tissue/glycogen/brain glycogen for energy, and is why many get a headache if they don't eat. rain is the first energy source. The Muscles/Protein.
Think of this.
When people lift weights, Run, or exercise in general ect, the demand for Protein goes up, because your body/muscles will be under stress, growing, and need Protein to Maintain, Repair, and Grow.Its not all you need, but is crucial
Protein in Latin means... Of First Importance.
The plant bypasses the protein conversion stage, and is fed straight Nitrogen.
I myself would use Chem Gro If I was going to use Hydro Chemicals
The have
4 20 39... Base
15.5 0 0 Calcium Nitrate.
Mono Potassium Phosphate 0 52 34
Buy Epsom Salts Locally.
Cheam Gro has an Exact Feed Chart for an 8 weeks flowering strain, and is easily lengthened, or shortened to suit your conditions.
I would also recommend using Dominion Seed Company
Dominion Skunk for fast growing, Sativa Dom, Med Heavy, Heavy Yielding plants, for an Indica Dom strain, and the Granny is Indica Dominant. These are also done in 54-66 days.
If you don't get at least close to 3lbs Ill eat your shoes. If the temps aren't to hot.. Over 84, and you also need strong fresh. airflow. I would space the 1000w Hortilux 4 feet from Bulb to bulb center, and 3 - 3.5 feet for the 600w. I would also keep the lights 24 inches, or closer if possible.
In the right season, I can get 1000w no more than 18-20 inches with good Airflow, and Ventilation.
I also would use at least 3 really really good fans for air movement, and make sure all the plants have some movement. I don't beat them to death, but if theyre aren't moving noticeably, I don't stand for it. I run the air between the Canopy, and the Bulbs, of which I also use Hortilux HPS Bulb 1000w. I also veg with 1000w, and all my seedlings ever know is 1000w. I use the 1000w for seedling at 24-30 inches. I start in 32oz Uline Deli Containers. Also have a fan on the seedlings.
Fans are on 24 hours a day in flowering too.
Chem-Gro | Hydro-Gardens
https://hydro-gardens.com/product-category/fertilizers/chemgro
