The answer is the root system...
You need to start a seedling, in a small Dixie cup or similar….
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Because you need to water the plant with enough water to water it “Through”
To insure that water gets to the bottom of the pot, where your growing roots will be….
Now, if you have a 4” plant, in a Dixie cup, you can easily pop it out of cup, to check roots!
You want roots to be very good before transplant…
First, your plant grows roots…. Below the medium, growing… then on top…
IF you do it correct, transplanting doesn’t cause harm to your plant, it makes it rocket grow…
Start Dixie cup-it comes out of Dixie cup, when roots go a round your cup, then you unwind roots, and put it… TP into .75 gallon…. When roots are going round and round the .75 then you transplant not before…
First root health, then your plant above medium grows, then you TP…
[Lots of holes in your pot… drill extra… Super Thrive to help root growth…] Good Luck