Once established in the ground -- that is, without a pot still around their roots -- they are very drought tolerant and will do extremely well on natural rainfall only.

So, yours is probably wilting because the plant is in the pot which, although it is in the ground, restricts root growth.

Even so, after 4 years in such a state, it's very likely the roots left the pot via the drain hole and are now in the surrounding soil.

But that "escaped" root may now be in trouble because of the likelihood that it is restricted -- choked -- by the limited size of the drain hole.

I think you are right -- and it will pay me back by being extremely hard to dig out! I should have made some extra large holes in the pot when I sank it but because it is gravel to help with our basement water problems I thought I was being clever. Sigh.

One of those live-and-learn lessons! (Everybody gets them.)

Fremontodendrons do seem to prefer moisture here. I believe unwatered Vashon Botanical Garden (a regionally significant collection of dry garden plants) still does not have one because method of planting in fall and using winter rains to get plants established, after which they are usually on their own has not worked for this item. Maybe has a tendency to be drought tolerant on heavier soils and not on lighter. Many dry climate plants grow in the wild on heavy soils but the climate is dry so they do not rot. Excessively drained, sandy soils used in attempts to grow them in rainier areas may dry out too fast and/or too much to suit them.

One I planted in Island County also had a wilting problem that was corrected by watering it regularly. One on dryish slope here doesn't wilt but grows much more slowly than one up there. Both flower heavily.

Mine here looking like it wants a drink now.

WEll, mine continues to have crispy leaves, especialy in the top half. It has two trunks that start near the ground and I thought I might chop the one out that has the most dead ones, but there is new growth along the trunk. I left a hose running on it all last night but this am it was no better. sigh. I think I'll have to pull the darned thing out, and that's not an easy job.

Crispy is a definite indication of dehydration.