Bakeroni, it's time to bring in tons of sand..LOL..Seriously though, is there some way you can modify the soil?

Is the wet area getting much sun? Perhaps this is one reason the kumquat isn't growing..no? How big is this tree? Can you dig up and locate to a dryer area? Sounds like the quat's been living hydroponically..if it's as wet as you say. (S)

I can't see any harm in potting the plant in a huge bottomless container..the roots will eventually find their way down in the soil when they run out of room..I'm hoping anyway..Toni

Bakeroni,

A portion of my yard in the winter gets sopping wet as well. I just got a quote this year from my gardner to put in a property drain (Basically a buried PVC Pipe with holes in it that runs under your wet area and slopes to a street exit) for about $800 if I remember correctly. If you have a sloping lot to the street (like I do), it's a lot easier. Should solve the wet problem. FYI I haven't done it yet because I am thinking I will keep the $800 and do it myself. Probably a bad idea...

The bottomless container should work except when the yard is soggy that water will be drawn up into your container because of (I should have been paying attention in Physics class) adhesion. Or is it cohesion? I would check on it. The good thing is, your "Container" will drain extremely well when the ground is dry because of the same principal.

How does a nursery mislabel a kumquat for a ponderosa lemon? That's like ordering sushi and getting a lamb shank. Anyway, I would check to see if your Ponderosa Lemon rootstock is compatible with the kumquat for best fruit production/taste etc.

Treesource uses the following rootstocks for their kumquats:
Nagami Kumquat ON Volkameriana
Nagami Kumquat ON C-35
Nordman Seedless Nagami Kumquat ON Volkameriana

If you just want to try something new, which will probably end up pretty cool, then just graft it and see what happens.

Have fun with your spring project!

Citrusboy