Several years ago a forum member (sorry--I don't remember whom) told of having good success with potted figs placed in a big tub with an inch or two of water in the bottom, so the roots always had plenty of moisture available throughout the heat of the day. I wondered about keeping roots constantly submerged, but tried it and my plants seemed to thrive.

I decided to expand the idea, and threw together a crude plywood tray with 2x2s at the edges to form a shallow dike, and then covered everything with a plastic sheet. I ran some drip emitters to it so the tray would fill to overflowing once each day, and put my smaller potted stuff in it. Usually by the end of the day, most of the water has disappeared, so the bottom isn't always 100% submerged:


Anyway, it's been working fine for years, with the following drawbacks: mosquitoes, and stinky, anaerobic soil in the bottom inch of each pot (which as near as I can tell, doesn't seem to hurt the plants any in my dry climate). I try to make sure there aren't any roots at the bottom of the pots when I first place them in the water tray, but often they grow roots right out through the drainage holes.

SO--my question is: Why bother with elaborate "self-watering" pots that have small reservoirs underneath? Is that really any better than just sticking a pot in a water tray, and keeping an inch or two of water in it? What am I missing?

My reason for asking is that I just purchased a 3 gal Pickering Mango, which can't survive Tucson's winters in the ground so it's doomed to stay in a pot. I thought I'd move it up to a 5 gallon container and then set it in a plastic tub fitted with a 1/4" water line and float valve to maintain an inch of water in the bottom at all times during the summer (in cooler months I'll let it dry out). I'll wrap the pot with a light-colored cloth that hangs down into the water, to shade the pot and keep it cool via evaporation. Then, I'll "cloak" the whole thing with mosquito netting to baffle the blood-suckers. The upper part of the soil will stay pretty dry but grow progressively wetter lower down, with the bottom inch always under water.  I figure the roots will grow into the zone of ideal moisture and avoid anything they don't like. Does anybody see any fatal flaws with this idea?

Check out my backyard video I posted a few weeks back. I did a couple of flood tables basically. Same Kratky hydroponic method.

Justin, you have a great yard-full of plants! I really like your flood-table set-up--do you leave those trays filled to the same depth all the time, or does it fluctuate or even dry out occasionally? Have you tried bottom-watering for 5 gal or larger trees? Do you see it as a way to permanently maintain large, container-planted trese--maybe even in something the size of one of those giant nursery pots stacked in your yard?

I'm wondering how many inches above water level the soil will be able to wick moisture. I hope to find a soil that works like a sponge--transporting water freely while leaving large air spaces for good aeration. I like the "gritty mix" idea in terms of air circulation and not breaking down, but I think it's designed specifically to prevent water from wicking upward.

There's a fella named Larry Hall who's got a self watering system you describe in various configurations and markets the items needed to make it.  He's all over facebook and youtube.  

I like your practical thinking, Ken.

I do something similar with 10-inch deep 5' diameter wading pools.  You can either put the plants on bricks, or just drill holes into the side of the wading pool to keep the water from getting higher than you want.  Works like a charm.

You can lay waste to the mosquito larvae by sprinkling in some Mosquito Bits granules (~$15 a jug at box stores).  Or, if you keep at least a little water in it the whole time, you can stock it with a few baby tilapia or some minnows; the fish will happily snarf down all the mosquito larvae.  I always have lots of young tilapia on hand, so I put them all over my property in the places that catch rainwater; then I collect them at the end of the season when they're partially grown, move them into a greenhouse for winter, and re-stock the rainwater pools with new baby fish the next season.

I use Mosquito Bits in most of my wading pools since I keep less than 1" of water in them, and since those pools sometimes go dry.  In the wading pools that I keep full of water (setting the figs on bricks or overturned milk crates), I use baby tilapia for mosquito control.

Hi Tucsonken,
I use individual plates for each pot - the problem here by me would be the same with one big plate.
Two weeks ago we started to have rainy days and of course the plates would stay full of water since the trees couldn't cope with the stored water.
So I had to toss the plates or the roots would rot and the trees would turn yellow. All the plates are still on the side for now.
With your system here, I would have to have a way to completely flush all the water when needed.

With bigger pots, you may have wicking problems where the first inches/cm at the top of the pot would stay bone dry.
You don't have that problem with smaller pots.
SIPs should have a wick to avoid that problem.

I use the gutter grow system as Charlie mentioned.  They're linked to rain barrels and floats.  Works beautifully.  I like your approach too, but the wicks in the SIPs are a little more indirect with watering the root ball, which I would think is better.  But if your method works, keep it going!

Thanks for all the input. Larry Hall's videos have given me a new perspective, and the Mosquito Bits sound like a quick solution (raising tilapia sounds intriguing as well, but to preserve domestic tranquility I'd better not think about adding yet another project!).

Now I need to come up with a pretty permanent soil mix that functions like a big, coarse sponge--sucking up water, while leaving air spaces throughout. I had thought of using "Al's gritty mix" but don't think it will wick water up from the tub. On the other hand, I worry that something with a lot of organic material will decompose and compress into an anaerobic brick over time. Does anybody know of a very long-lasting mix that would provide both wicking and good aeration? 

Having side holes to prevent over-filling during rainstorms, as well as a bottom drain for occasional total drainage both sound like important features. As far as growing medium, I checked with a friend who grows a very wide variety of plants, and he recommends a mix of coir and pumice (or coarse perlite) with a little vermiculite and dolomite. If anyone is interested, here's an article he wrote about coir and how it has been improved in recent years. It sounds like the ideal growing medium:

http://www.tucsoncactus.org/html/growing_in_the_desert_column_June_2013.html

He said that bottom-watered coir might not wick moisture as high as I want, and also cautioned about salt buildup, so I decided to modify my approach with a combination setup--using a pan with float valve to ensure a minimum half inch of water at the bottom, but with a water tube running from the valve up to emitters at the top of the pot. That way, any time the pan level drops below a half inch, the tree will get watered from the top. There will be some lag time between when enough water trickles down into the pan to turn off the valve, and when it finally stops percolating down through the mix--so the pan will likely overfill a little after the valve shuts off, but in my climate that's fine. Then, every couple of months I can drench it thoroughly with the hose to minimize salt buildup.

I used 40% compost, 40% peat moss, and 20% perlite by volume in my 5 gallon sips this year.  It seemed to work pretty well.  All of the trees grew well and look like they may already need root pruned or moved up to bigger containers.

Don, with that mix....how often did you have to water your trees?

A good number of my trees are in 27 gallon SIPs---Bill's method.  On a 90 degree day, those in pure compost only need water once every 4 days.  Those in a compost mix plus perlite and other stuff HAD to be watered daily!  If not, the leafs would sag and stress would begin.  I did a test last Winter and only mixed my compost with just one tree.  That one tree has been a thorn in my side every since.  The others can do days without water.  I think I'll stick to Bill's method of SWPs on all my trees.  You can't argue with success IMHO.  I will be repotting that tree next month.

I had 7 trees in 5 gallon buckets interconnected with a 5 gallon chicken feeder type reservoir bucket on the side.  I'm guessing that there was roughly 15 gallons circulating through the whole system.  The tops of the buckets were covered with plastic so water shouldn't have really gotten in our out.  

I ended up adding 3 more trees for a total of 10.  As the trees grew and the temps got higher, I went from filling the reservoir that fed to all of the trees once a week to about every day or two with roughly 5 gallons of water.  

Now that's it cooling down, they haven't been sucking up as much water but I haven't really kept track.  It's been easier to just dump some water into the reservoir than to fill up the "chicken feeder".

I've never ran out of water and only had some wilting early on right after I potted.  A little top watering for the first couple weeks resolved that.

The tallest grew about 7 ft since being potted in the sip in May.  It was about 6 inches then.  All of the cuttings were started in October or later.  4 of the 7 managed to fruit.

Here's a pic.  Buckets are ugly but it's whatever.

 

Yes, The Garden Pool in Mesa, AZ now uses coconut coir as its grow bed medium in their aquaponics setup (where they have grown trees as well as other plants for years). 

Thanks for sharing your interesting, home made invention. Very clever! Many cactus growers keep their rarest cacti specimens in pots. They use pumice as a soil amendment. It doesn't float out of the soil mixture the way that perlite does. "Pumice is a light weight stone used to amend garden soil and provides improved aeration and moisture retention while maintaining a reduced soil weight." http://www.acmesand.com/soil-amendments/

 Hi, I wanted my fig tree to be portable, transportable, and also located on our patio, so I constructed a 'self-watering-barrel'. Mine is made with a 55 gal food grade plastic barrel. Any youtube video on this topic will show the essential desgn elements which then can be designed into the 55 gal barrel(s). (soil wick, soil tray (top pf barrel), air layer to separate the soil and water. screening on fill hole, etc).   It works. The 4 year old fig tree ( some dwarf apple trees too) are doing fine. Issues to consider: The top of the soil can dry out so it has to be top watered ocasionally. In the heat of the summer the water resoivoir will need checking and filling daily, unless hooked to a float valve or drip system. It is heavy (~300 to 400 #'s) so make sure you are okay with how to move (large dolly, etc), and the structure (patio, deck, etc) can handle the loads. The barrel's outside can be decorated with fabric or wood slats, and this essential to help keep the roots cool. I trim my trees to stay within a resonable size for my convenience but also for wind considerations.