depends on ya soil......basically your feeding the plant boosting the soils content of nutrients for it to access.
as far as needed,,,,,no not under right conditions.
if your plants were in the same RICH soil,
,say some the hawianian islands volcanic stuff ,best dirt on earth i would think.you would probubly ruin ya weed by ferts,cuase outdoor ,you cant really FLUSH the soil ya know,what you put in the ground,matters more than what you dont.nitrates build up and PH levels go up. etc ect....im sure you have read up on ph levels.


if the soil is some worn out shit that only scrub brush grows in then it would matter alot if you added ferts.

you get the right soil it dont need nothing but water and sun
but that is hard to find in a safe place to grow

your main concern outdoor,is its being HIDDEN

you cant put it in the middle of your corn patch (anymore) in any numbers one or two maybe,risky shit now with the choppers,cant have it even close to home.
forced to put our plants out on their own, picking soil is very important skill you get over time ,do it for 20+yrs and you can almost smell the dirt and tell if it would grow anything.,,,,almost that is,lol
peace