Only a couple of months? I thought they were slow growers, yet this one doesn't look like a juvenile.
Ah, I know what you mean with diggers, I used to keep a planted goldfish tank.
If you ever want to try again try wrapping the roots and soil in layers of fine mesh and cover it with an upside down mesh box, the leaves and sprouts can grow trough the top. Then you can place rocks on top.
For the mesh I recomend an old pantyhose or fruitmesh.
example ,
Second sample,
boxieJust make sure the mesh isn't too tight. The plant still needs to be able get water circulation, and grow trough it.