:smoking: hey Frank! ....looks like my partly completed post here got cleared out!
,.... anyway, you know the deal as per our PM!
... I'll just drop some notes in from the start as I roll through,...
-- mind the
soils mate! For some time now, their quality has been very spotty. Many folks have come to the Infirmary with badly off pH issues stemming from the OF soil, sometimes HF too... I myself have measured in-bag pH's on both, and they were in the low 5's!
Others get OK bags,.. it's all about the local sourcing it appears... Steer clear of them unless you can test first. I recommend the Accurate 8 soil pH probe fior getting direct measured in-pot pH, far better than the damn run-off method, a crude estimate at best usually, but if done right can do in a pinch. There's a sticky article here in the Infirmary (right above this section) that shows the improved method and calculation, along with several others! Alternate soils with good rep' are Roots Organic and Black Gold; Roots needs a little extra lime in it for better pH buffering down the road, and BG is a bit heavy, so add perlite,...
-- try fabric pots next round, same general benefits as air-pots, but less messy and leaky (if you get good ones, not cheapies)... air-pruning of the roots, and more even drying top to bottom,...
-- that one seedling with the odd color breaks is something we see time to time,.. not sure what's behind it, most grow out fine, losing it as they mature,...sometimes not! not an issue now, so on we go...
-- LST, you'll have to check out around here, but Yeatster has already covered that,.. I'm usually outdoors, so I don't bother, but I want to learn for indoor applications... The results speak for themselves! Check out A-Trains grows and tutorial... the yields he got off the Big League Chews (and others) were for sure better than untouched plants would have been!...
... plant height ain't an issue for you this time!
Mate, when new at this, use the KISS principle, LST is not always the best answer, and the plant has to be in great shape and growing just right (stretching) to make it worth while,... As you found out the hard way!
Also, MH spectrum and strong intensity may be why they didn't stretch much,... Is you HPS a broad spectrum type? If so, it may have enough veg wavelengths in it for early switching, even if not blooming fully yet,.. red spec' will help stimulate stretching some,... *Oh, done already!
-- if you need to acidify your soil, pH'ing your solutions and water will work fastest and best; top dressings act slow, and unevenly, and elemental S is useless slow! ... nute solutions are acidic normally, and if you need a mild pH down product, simple citric acid for canning uses is fine, no need for the harsher bottled stuff,... I used it all season for adjusting water on the "supersoil" product KindSoil, which is a pH'ed water only deal,...very small amounts worked great on 180ppm tapwater to get it around 6.6... what type lime did you use, Ag' or "garden" lime, or dolomite? the latter is slowest acting of all (chemically different than the others), especially if it's course grained-- too slow for practical use with auto's in fact! near powder grade is faster,... at least with dolomite, it won't raise the pH above 7.0-ish, but will resist consistent lowered pH in soil until depleated! Again, I see no problems, so just note this for now,... Epsoms will not lower pH, it's just for getting readily absorbable S and Mg in there quickly...
-- plants look great dude!
...get me normal light pics of the spots to diagnose... HID and LED light is lousy for color rendering, an important factor in assessing issues,...