I got 2 plants 6 weeks into flower. Nice looking buds but no crystals.
It is some bagseed I vegged for about three months....out door veg.
It is now under 400w HPS and has been under for the whole 6 weeks.
Are you sure thats 6 weeks? Looks more like four but with bad seed you never know. Might be genetics.
Some strains show hella crystals and some don't. This does not mean its not going to be strong weed but some strains just have small res glands.
I normally see them right away because of the genetics I like to grow.
Since those plants are pumping up slow and with the way they are growing this bagseed might have produced a sativa dominant phenotype. If thats the case you might have a long flower cycle.
I didn't really start to notice serious crystal production on my irls intil about the 6th week. Your plant looks very sativa-ish, so I would expect you to start geting crystals over the next couple of weeks. Don't fret cos your plant is looking very healthy, and will most likely give you a pleasing result. Be patient matey, and "They will come". Happy growing.