Miracle Gro Moisture Control is reasonably cheap, easily sourced, and stays damp for longer periods as long as the tree in question isn't drawing the liquid (if it is, like my winter ageratum-in-a-can, the soil will happily give up its water very easily). For a single plant, it's probably easier than making a custom mix. It's what I tend to use as I dislike fiddling with custom mixes for standard plants that don't really care; I have other things to do.

Mulching the top of the soil with shredded bark or pebbles will also help keep water from evaporating quite so easily. I mulch my outside pots but generally don't bother with the inside ones.

Custom mixes are going to involve a lot of compost, which will also retain a great deal of water (and decay off over time, but one simply adds more mix up top and re-pots occasionally).

Some do recommend water-retaining crystals, but I can't personally say I've had a vast amount of good fortune with those under any circumstances.

taxodium grow fine in my hot drought stricken sand here in MI .... though they tolerate wetness ... im not sure its imperative ...

they also tend to grow like weeds .... how long do you think it will be in the pot ... i bought 6 foot whips i one gal pots in sand at .... get this.. big lot.. when i first moved here .. 5 bucks if i recall .. and 3 years later they were 15 feet tall ... i wouldnt call that foo foo trees they need special care .. lol ...

why are you making this presumption [perhaps some experience you left off the facts] ...

anyone recall when they unpotted a taxiodium.. that the grafter/grower had them in media any different than any other conifer???

ken

Isn't staying wet in a pot different than being in a wet area outdoors?

well.. sorta ... but natural drainage.. might be different than drainage in a pot ..

many water loving trees .. dont literally stand in water all year long ... short of the swamp/bog trees...

its the difference between a 'tolerance' for such.. compared to the requisite need for such ... taxodium tolerate water ...

and im not sure i would ever use water crystals with any potted tree ... in fact in my experience.. i wouldnt use it with any potted plant ... but if you figure out how to do it ... all the power to ya .... [keep in mind.. in my MI.. the ground freezes.. and pots freeze solid ... and god knows what the crystals will do dealing with that ...]

ken

"nd god knows what the crystals will do dealing with that ...]"

They freeze and shatter into much smaller crystals. They still retain water...er, ice...but... :-)

Yeah, that's why I don't use the things. When I had them, they were mildly useful when transplanting small things into the gardens in spring. Even the more developed ones were entirely capable of taking care of themselves.

"well.. sorta ... but natural drainage.. might be different than drainage in a pot .."

It is. The MG soil I mentioned is pretty light and doesn't waterlog easily, but does hold a good amount of water. Root rot hasn't been an issue with anything I've tried. I do leave my pots out, even plastic ones, and they're fine. I bring more delicate ceramics in as they'll shatter, but leave heftier terracotta ones outside, the one I own (I dropped the other one).

We can have the discussion all day but...well, I tend to be a lot less choosy on soils than many around here. Pretty much everything gets plunked into MG soil and does great, including a couple of desert roses before I knew better. On that one, though, I think I got lucky and I did know not to water to excess.

I suspect you want to induce buttress roots (cypress knees as they are called) like the wild bald cypress growing in swamps. Those tend to form more readily under flooded conditions. In bonsai it is a sought after characteristic of bald cypress. One technique that is often applied is to partially submerge a potted tree in a larger tub of water. The water needs to be replaced every few days to prevent anaerobic conditions. Moving water is best and can be achieved with a small pond pump to keep the water somewhat oxygenated. In winter the plant is removed from the water basin. It takes several years to develop those cypress knees. Although not very fussy about soil mix, for a woody plant in a container your way better off using a structured durable mix that drains well.

My in ground bald cypress has very nice buttress roots that flare out about a foot from the base.

'Moving water is best'

That's what I was getting at.

Stagnant water sitting in a pot can cause more problems than not. Even swampy 'pot holes' out in the woods can get anaerobic during the summer, because there's no 'flow' to keep it refreshed or aerated.

Swampy areas along river bottoms, even if not directly connected to the river itself, don't have a problem because the water is being continually refreshed by the groundwater. Same goes for inland swamps that are fed by underground system of water veins or streams.

I can't see where having a pot full of slow draining soil that stays soggy or wet will produce the same effect as trees in nature aside from installing the pumps and circulation systems mentioned.

Well, we haven't heard back from Stewart yet. He might just be a Forgetful Waterer. :-) I'm kind of guilty of that sometimes with the outside pots myself if I get busy and distracted...