What area are you growing indoors or shed loft ect and what size pots are you using for your plants and what area is it and how many plants? 400g is not easy in fact it's 14oz from 1 plant and your new to growing do you have any experience with growing and why do you want to get 400g please your going to have to veg them for 6 months and then flower it for ages and the fact that you're going to have to train your plants and you have still the problem with them growing isn't as easy as people say and I think you have no chance of getting any things close to what you want most plants yeald 2oz and that's decent yeald 56g a plant but I will watch and see the outcome but your area temperature and environment will always need to be perfectly maintained for decent yeald and you can't just leave them be with self water your plants need checking on for issues regularly and to get 400g will be a long time veg before they will even flower so your not going to get any buds tull around Christmas time and if you get problem like hermie plants then all buds full of seeds and lots of wasted electricity costs etc but good luck and I would be lowering your expectation if I was you
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