I'm feeling pretty good about where to go with this, only issue is I don't know where to find the right soil and from there I know nothing about what kinds of nutrients to give, how much, when, or how often..
Everybody is gonna give you different advice but I can make this incredibly simple for you.
Go to a home depot/ lowe and buy a big bag of potting soil, you pick the brand, it won't really matter, while your there get a box of miracle grow 20-20-20 which you can use until they go into bud, when you switch to 15-30-15.
Dig a big hole and fill it with the bagged soil you bought, you can also mix the soil you dug out with the soil you bought.
Plant the seedlings and just water them for a week or 2 until they really start to grow. When using the miracle grow get a 1 gal. jug and start with just a small amount per gal. of water. 1/2 tea spoon at first once the plant starts to really grow branches and become a plant instead of a seedling start applying one scoop of miracle grow to a gallon and just water the plant. One gallon of miracle grow water per plant every 2 weeks.
One the box of miracle grow it will have directions. Treat marijuana as if it was a tomato plant and follow those directions.
When the seedling plant has 5 nodes, which are sets of leaves, start at the bottom, that's the first node, when the plant has 4 sets of leaves and begins to grow the 5th set cut the top off just above the 4th set of leaves. This will cause 2 things to happen.
1) It will cause 2 tops to grow instead of 1, 2) it will cause a hormone to activate the lower part of the plant causing a massive growth boost. Instead of the plant trying to grow 1 tall cola and growing sparse, it will become a shrub and produce many tops and branches.
When each of your 2 new tops have 2 sets of leaves (nodes) cut off the the next tip right above the 2nd pair of leaves, this will result in each cut producing 2 more tops. At this point you will have 4 main colas and several side branches, a nice little shrub.
You need to decide who you are going to listen to an stick to one set of recommendations. We all have our methods. I like short plants with multiple colas. If you do it my way you'll have plants like these.
multiple tops, - same plant a month later - 5 plants in all-- same 5 plants in bud
These 5 plants were grown the way I described above, If this is what you want, do it my way. Like I said everybody has their own way, I love my way
As Dale Earnhardt used to say
"There's two ways to do this, My way, and the wrong way!"
Its up to you but you need to follow one path and stick with it. My way is really easy, this is a plant were talking about, some people make it sound like rocket science. If your new at this keep it simple, I've taught a lot of people my way and it becomes their way and they are teaching others their way and so on and so on.
Pick a grower and follow their advice or do it your way and see what happens. My way will produce shrubs with lots of buds...