Not only is it a concern, it is a problem. Growing is not like baking, if you follow the directions your going to ruin your cake if you get my drift.
The key words in that sentence are has been growing, your plants needs may be different than the nutrient gives or the nutrient solution has finally gotten toxic enough to affect the plant. Not everything is immediate with these plants, infact ... nothing is immediate.
Sounds good, do the bulb switch
Add it when you change nutes, just mix your nutes and pour it right on in to the res.
Topping a plant is usually done on plants that have grown to their expected height or a method used to keep a plant short. It involves cutting off the maristem where you want the vertical growth to stop. Considerable stress is involved in this as the plant creates new auxins rather than redirecting them.

LST is called "limited stress training", basically tying the main cola of the plant down as low as you can so it produces multiple colas off the lower growth. Auxins transer from the main cola to the lower growth and the plant gets bushy.

ScrOG is short for Screen Of Green, basically placing a screen across you canopy in the lights sweet spot to "train" or tie the plants to as they grow to spread out the new growth in a controlled manner as to not crowd other buds.

FIM is short for Fuck I Missed, and it is a bit more advanced.

Supercropping is basically LST without strings, you damage the stem of the plant to make it bend rather than tie it down.

I'll expand on that later.

~GG420

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So how would I go about topping the plant? That seems like the easiest thing to do, but what will that do to my yield?

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I can't even feel myself right now

Unless you have space restrictions Topping isn't really necessary. I prefer to let nature take it's course in the summer w/ my outdoor crop. My indoor crops I sometimes top for space. SCROG is another cool thing to do w/ space restrictions
The yield depends on how and when you top. I would look up some topping threads, esp uncle bens then decide.

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I'm calling karl!!!

If it were me...

I would LST it down for the first month (just the meristem) and then attach to a scrog and veg another month to fill the screen 1/2 way up and then flower, this would give you the best yield in my opinion.

Topping stunts the growth more and I like the results of LST because you still keep you meristem and that is where your main cola grows plus it is putting off new growth to help fill your screen.

Be sure to use the search engine there are plenty of topics on training techniques to improve yield.

~GG420

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I have extreme space restrictions, I have 8" from pots to lights, and the plants were 4" at Flowering

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I can't even feel myself right now

Screen is goin to be your only option, put it in now.

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Why couldn't I just top the plants?

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I can't even feel myself right now

Topping the plant will not stop all growth up, a screen will. The plant will easily still grow into the lights, your going to want an easy to control canopy and you will get a better yield.

~GG420

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So should I get fine screen like for a window or chicken wire? Thanks

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I can't even feel myself right now

Chicken wire or something large, just be sure you can tie you plant to it and all.

~GG420

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