Sensi Jack here

I've grown Jack's 3 times over the last year (all photos), and while they aren't light producers imo, they aren't going to give the yield of like a white widow or sour diesel.

Heres one about halfway through flower from back in June (the topped ones we screened out to about a 2x4 section of tent, so they did well both ways.) I travel a lot for work, so this pic is after almost 80 hours with no nutes and only 1.5 liters of water (drip feed system fucked up, lower nets are to keep cats from trying to jump up and nibble the leaves when I'm in the tent)

I can say for sure Jack's are a pretty tough strain even if they aren't bud monsters. High is still nice an focused (for me) like it always was, although not as mind wracking as some of the high end shit out there now.

I usually smoke it as my daytime weed.

As to your question, if you are looking for max yield you might want to try another strain, Jacks seem to be avg to slightly above or below producers.

I guess I'll put it this way, I usually grow a couple jacks a year, but never an entire crop worth, just too many other options out there.

 

If you are looking for sour D seeds, I've had good experiences with North Atlantic seed, specifically the ethos genetics feminized (don't do autos so no opinion on those). In the summer though, they do get out of stock from time to time.

So the unfortunate reality of my grows is that we are strangely enough, not looking for the best yeilders, but rather, the plants most responsive to variations in the par spectrum that current grow lamps may not be providing. (specifically some wavelengths the old blurple lights put out, that modern LED panels sometimes lack or get interference on even though overall, they do far better than just blurple lights)


Eventually plans are in the works to get some onsite cloning going, but at the level we are at currently, we are more focused on overall effects across seed grow strains. When we think we've got something promising, the plan is to move to straight clones to dial everything in with minimal plant variations.

Def some people in here more on the business side of things that can prob point you towards the big yields better than I can.

I've been working exclusively with Gelato-33 and whats commonly known as the "d" or heavy sativa pheno of jacks (for research, grow other stuff for fun too), its possible you had one of the heavier indica mix pheno's of Jack which I have heard can produce like a boss. (if our plants were doing 22oz each no work would ever get done here lol)

I think once the summer crops are done, we will try and replicate results with new strains, specifically looking at GG4 and some Dr. Grinspoon, (something heavily crossed like GG4 vs Grinspoon which is pretty much pure sativa. The rounds after that will hopefully focus on another mix, and a heavy Indica like Afghan Kush (also a good producer, but I don't know if its what the "cool kids" are smoking these days).

Grow a shitload of sorghum , peat moss and some other stuff, but no one wants to see that lol.

The goal is to eventually isolate what conditions cause the chloroplasts of varying strains to function at maximum efficiency, coupled with what conditions can cause certain strains to naturally develop more dense chloroplasts per leaf surface area. Side notes are being made on various lights used in the process as well, so we get some more generally useful data too like between a spider farmer and mars hydro light that both pull 450W from the wall, which one actually puts out more photons and in the correct spectrum.

Between Mars and Spider btw, the difference so far has been insignificant in output quality at similar model levels (100W / 300W / 450W ect) so use what you like imo.

Most plants are only catching a small % of the light you throw on them and using it for ATP to grow fat buds and thick stalks, some friends and I are focusing pretty narrowly in that area, specific molecules that might be enticed to form bonds slightly differently and in more efficient ways by regulating the precise amount of photon energy received from a light, coupled with regulations in wavelengths on the light itself.

Its mostly volunteer work though, so we must do the best we can with what we have.

Sometimes the methodology is less than perfect with the experiments, and setbacks occur, and we get reactive oxygen molecules that damage the plants, sometimes tensions run high after failures.


Anyway man hopefully someone else can point you on the current biggest yielders, questions about lighting, and light related problems though, always happy to help when I can. When it comes to photocycles I and II....



Final note, the gelato-33s have always been above average producers. One plant vegged 8-10 weeks easily screens out to 2x2 area, or reaches almost 6 feet if left un-topped during flower. They have a slightly smaller PH, temp, RH and light range where they are happy though compared to something like AK-47 or green crack that can take abuse like the Jacks.



Foreground plant is a Gelato-33 approx 8 weeks into flower. Right behind is one the Jack "D" phenos (you can tell from the lighter leaves around the jack buds)

Like I said, both have been decent producers, but the trichs on the jacks are insane, shitty quality due to zoom but the gelato bud is on the left, and somewhere under all that white on the right is a Jack bud.


Best of luck mate, hopefully someone with more knowledge in growing for max yield can give you some better advice on strains best suited to that.