imowhat's the best way to re-use the old soil from previous grows..
it really depends on many variables
i would think for most,its the practices used during the previous run & wen developing the soil...
feeding the plant,peat based mixs,super media amending,bottle formula approach too endless diverse mulching,ACT,biochar,compost/casting based soil & so on
heres an example of a no-till 15gal container
seed was planted right in the mulch
here are more no-tills just that we T-planted some starters in
(mater,zucchini,beans,greens,etc )
& here we have some seedlings
germed in peat/grit & T-planted to 100% recycled soil..
method & results were the same but with soo many containers of rich soil & bio-accumulating plants thriving,this recycling method helps with much needed space.
dumping many into LrG batchs along with putting good use too the tons of organic matter & cured compost,a ecological urban garden tend to reap..large smart pots,fennel greek/buckwheat cover & proper irrigation is how i role