Welcome to the forums lacika
First of all I would Introduce yourself in the introductions thread -
https://www.autoflower.org/f35/ here you can say hi and other members can welcome you in to the fold
Window sill growing won't give you the best results as the light only comes from one side and you haven't said which way the window faces.
Ideally it should face south if your in the Northern hemisphere and North if your in the Southern hemisphere.
Cannabis like a decent ammount of light and without it your seedlings will get leggy.
One problem if you decide to go with Photo sensitive plants outdoors, is if you plant in spring they can grow huge before you crop them in the autumn.
This makes them easier to get spotted.
Planting photos late in the summer will keep them smaller and they will be in the wild for less time, both good points to help keep them stealthy.
I would advise a Auto variety be chosen and avoid any that get too tall. Auto Northern Lights is a easy to grow variety will relatively low odor, not tried easy bud , but the clue is in the name
All mix is gonna be to hot for your seedlings better to go with Light mix, I don't understand what you mean by tiles , Seed trays possibly?
I don't know which part of the World you are in so I am unable to advise the time you start your seeds and when the best time to plant them out, something you will need to let us know {Don't give your exact location, just the country and if it is an exceedlngly large country ie USA then you could mention the state}
Prepairing the ground before you plant is a good idea, dig some holes and fill with good compost nearly to the top and then back fill with the soil you dug out, this way it disguises the holes as compost filling them is likely to be a different colour to your native soil.
If there is natural dead vegetation on the ground scatter it around on any disturbed ground to make it blend in with its surroundings.
Try not to plant your plants equidistantly or in a geometric pattern, get some walnuts or any item you can throw a handful at a time {you could cover then in foil to see them better} and scatter them in your desired planting spot. They will fall randomly and this will produce a better pattern not to be detected from above. Where they fall is where you plant, if two should fall too close pick one up and gently chuck in the desired direction.
Topping the plant when they get a few feet tall also helps by stopping them from having that classic Christmas tree shape.
You will need to feed them and as your using Biobizz compost May as well use Biobiz to feed them , especially as your growing next to a river.
Be careful though rivers attract the likes of fisher men and people like to walk by riversides, who may make of with your plants or worse yet report them.
You are best off choosing a site that gets full sunlight for at least 8 hours a day which will be South facing in the Northern hemisphere and is not regularly visited by other people.
When growing weed it is best not to mention it to anyone!! Loose lips sink ships!
The best thing you can do is to read as much about growing cannabis as you can and also read as many out door grows as you can especially auto grows which will finish much earlier.
Drying in your basement you may need to buy an extraction fan and carbon filter which are fairly cheap to buy. Your weed will stink as it dries and people might smell it, this has been the downfall of a number of growers.
You don't want to have anyone smelling it & giving the game away.
Even if you live in the middle of no-where, I expect you get mail delivered and thats all it takes, just one person to smell it and your grow could be all for nothing.
There is load of info in the forums and many questions that are frequently asked which have also been answered.
The members here are a helpful lot and will help you in your quest to grow some and will have strain that they will suggest and info I have missed.
Growing is a learning process, your first crop might not be as good as you like but keep persevering and every grow should be better than the last.
I wish you all the best with your grow but make sure you get some knowledge in before you start.
Thanks for takeing the extra time to help this new member,.Arty.
