Yeah i get a little anxious when it comes to my girls, and this is my first outside grow. Any info on transpanting to a twenty gallon pot? Not right away of course but could i go strait from a 3 to a twenty without it hurting anything?
I went from 2 gallon pots to 25-30 gallon pots a few weeks ago myself, just be careful and sprinkle a bunch of mycorrihaze on the root mass and in the hole you dig for it and you'll be golden. Just be careful not to overwater until the roots have filled out a little more or you run the risk of slowing things down even more.
In fact, although it's hard to say without seeing it, I'm be willing to wager you aren't really seeing transplant shock but it's just the plant getting used to it's new home. Your plant went from a 16oz solo cup to a 3 gallon pot, so your tiny seedling suddenly just got a lot more room to spread its roots than it had before and is focusing more on that than anything above the soil. Give it another 3-5 days before you start tripping out too much, I'm sure the plant is just stretching it's roots and once it has more of the 3 gallon pot filled up with roots you'll start noticing the growth you're wanting.
Consider this, it likely did the same thing from sprout in the solo cup right? For a good couple of days, it was just a tiny little seedling with a tiny little taproot. But over time, as that tap root slowly began to fill your soil, the plant itself began to grow as well yes? You'll have this exact thing happen all over again when you transplant into the 20 gallon pot.
If you had transplant shock, you'd notice it. The fact that you're only showing "stunted" growth and no form of actual shock leads me to believe they're just fine and simply need a little time to fill up the bigger pot with roots
The only way you're ever going to avoid this stasis in growth is by eliminating the need for the plant to re-adjust and the only way you can do that is if you start your seed/clone in the final container. Although outdoors this isn't exactly always possible, you can start your seedlings/clones outdoors in April under a clone dome and transplant them to the final pots when they're good and ready.
