The Meyer lemon tree roots so easily, that it is very very very common to find non grafted Meyer lemon trees, that instead of being grafted are produced as rooted cuttings. The cutting they use are mature cuttings, and should come into flower rather quickly. All they need to get some height to them.

Silica, the tree I was wondering about was the navel orange. The Meyer is blooming great this year after being fed!

(I shouldn't have muddled my question by adding the Meyer lemon photo but i couldn't resist.)

KC

KC in my experience oranges take longer to bloom and fruit, I have a Valencia Orange that did nothing but grow for 8 years and then finally bloomed on the 9th season. My grapefruit took about 6 years to fruit. Mind you these are grafted trees I'm talking about. It is possible for commercial nurseries to sell rooted cuttings but in California it is highly unlikely because grafted trees are easily obtainable and not that expensive. You say that your tree has been in ground 4 years, by now your graft line should be difficult to distinguish if it was a good graft and a compatible rootstock was used. The whole point of grafting is to get the trunks to blend so that it's nearly indistinguishable between scion and rootstock transition. Patience is your best friend when it comes to growing citrus and I've found that fertilizing at the right times of the year is key to getting your trees to bloom and hold fruit. On another note, Meyers are prolific bloomers but will self thin fairly well so I'd leave your flowers alone on the tree until they're marble size and then thin out if you think it's holding too much fruit.

Evan

Evan, thank you! As always, I learn so much from you!

Here is a picture of the trunk, just in case y'all see something I missed.

The bits cut off at the ground at the very base were a blackberry vine that somehow grew in there. I didn't know what else to do but cut them off at the base and hope it would go away :)

KC no problem, that's why we're here so we can learn from each other. Can you dig down below the mulch it looks like your graft could be just below the surface, not sure though. Here's the area I'm talking about that looks like it could be a graft line.

Evan, should I uncover the graft line, and keep it exposed?

I would just pull the mulch back a couple inches away from the trunk. Keeps moisture from sitting right against the trunk that could potentially cause rotting issues.