New to the game.

Next season I would like to start a 10 plant outdoor grow using The big bud feminized. I plan on digging out my existing soil (about 3 cubic feet per hole). and filling with some ocean forest. How much room should I leave between plants. are there any additives I should blend with this soil ( coco coir, perlite, worm castings), and should i be concerned about the ph of this soil throughout the season?

Growing now? Is not your season almost over?

Miz perlite by the bucket. That is for sure. Drainage will be your friend. It would be the ph of your run off that would matter more. If you want to grow trees leave them around 3' minimum from eachother.

yea do with the last guy said, mix perlite in with them, you should be cool with just that mixed in if you are useing fox farm ocean forest. and you should invest in some nutes as well ahead of your grow.