Mango, Avocado, Papaya

I have a greywater growing bed attached to my porch in Texas.  It is set up pretty much like the ones in the earthships - the greywater goes into a bottom resevior with rocks, the dirt wicks it up/roots grow down to it.  It is mostly hot here, but I will close in the porch for our brief "winter" to keep the plants warm.  I want to try some more tropical plants.  Earthships usually put banana trees in the planters right away, which I have already done too.  Any experience with mango, avocado, papaya?  Do y'all think they would do ok in a greywater box or better to keep them in their own big pots on the porch?  (I'm very careful to keep chemicals and salts out of the drain).

I am not real familiar with these grey water set ups. But I do know tropical trees.  They are thirsty, but don't like wet feet.  Papaya in particular tends to get a lot of disease in overly wet soil conditions... And mangoes and avocadoes are BIG trees... So I am not sure how they would manage in pots.  Mangoes can be pruned viciously though, so perhaps it could be kept at a manageable size...

Ha, I don't think I helped anything!

You can look into the methods of bonsai. That is the art of seriously dwarfing a tree. I am currently keeping a small forest of sycamore figs (ficus sycomorus, aka biblical figs) at about two feet instead of 50' and 2" leaves not 10". They won't bloom or produce fruit though with those extreme methods. Still, a methodology of careful water, well draining soil and purposeful methodical pruning to keep trees smaller might work. Try Fourwindsgrowers.com and I'm looking for one more website for a lot of  choices and some avocados better grown in pots than others... some trees will be smaller and more easily adaptable to container growing than others. Do note that avocados are unpredictable when grown from pit, the usual store varieties are Fuente x Hass, and the ones you get were fruited by the Hass and won't breed true. You need to purchase/obtain grafted/twig cultivated not seed cultivated, AND. Avocado bloom both sexes, going male in morning and female in afternoon, or the other way around. So you need an "A" and a "B" to get fertilization. Growers often graft a Fuente branch onto each Hass so they take care of the issue themselves.

I currently have a 'columnar apple' for cross pollination of my other superdwarf Lil-Big trees. It could be trimmed to keep it within say a 18" to 24" pot and 4' to 7' tall. I let it grow, planted in the yard. I topped it at 12 feet, and it needs topping again. The straight trunk did put out some side branches because I let it do as it wished versus keeping it trimmed of all side branches.

So for any of the trees you choose, try to get a dwarf that will grow in pot culture, and be dedicated to giving the extra care it needs, and you should find some that will work in your intended setup. I will edit when I find that site with the trees I am going to order from after I have a permanent greenhouse...

Dwarf tree varieties already exist for each mango, avocado and papaya. These can be grown from 4ft tall/wide up to 10+ft tall/wide and they produce full-sized fruit. If properly maintained and harvested on a cycle, you could potentially be eating these fruits all year long when grown in a greenhouse. These trees can grow is separate pots or in your greywater system, especially since you mentioned being very careful about what goes down the drains. Even for those not careful about what goes down the drain, a mycofiltration system (fungal filter) could be added to filter out most chemicals and salts. This filter will still need regular maintenance, but is much less work than most other filters (harder to initially setup, but then needs maintenance less often).

Edit: Just noticed a great thread on mycofiltration found right here at Permies. Mycofiltration

Hope this info helps.
-John

Hi.  Great idea for using the grey water for wicking bed.  I did read somewhere that grey water was not recommend for wicking bed.  I dont know why. Only reason I could think of was the water not being safe for the plants or if you plan to eat the fruits or the produce from the wicking bed.  Second maybe because it may smell as the grey water is stagnent in the reservoir.

I assume a wicking bed is not much different to a subsurface constructed wetland.  Grey water is channelled subsurface through a gravel layer.  Top layer is planted with plants whose roots absorb the nutrients either through a wicking effect or direct contact by roots.  

I am located in the tropics as well and would like to build a subsurface CW for my property however I am stuck on the depth of the gravel layer, sand, and soil.  some do it this way and some that.  

Anyways I hope it works out.

Avocados are prone to root fungal diseases if they don't have good drainage.  That's why they are usually planted on hillsides.  You don't want them standing around in saturated soil.  Mangos, on the other hand, like a lot of moisture.

What is your soil like?  If it's highly sandy and water percolates down through it quickly, you won't have as many issues.  But if it's heavy clay, like mine, you are asking for trouble planting trees where they'll stand around in water much of the time.

You might consider some sort of system where you can run a hose and pump that grey water to the trees when they are thirsty, and then redirect the hose away once the soil is well saturated.  I've done this with our dishwasher and washing machine, as both have a pump that pumps the water out.  There isn't much friction or rise, so the water can be pumped a good distance away from the machine without over-burdening the little pump.  You just have to make sure you don't have a kink in your hose or you'll eventually burn out that pump motor.  The other advantage of doing it this way is that you don't have massive trees growing right next to your house.  I water my citrus trees almost exclusively with the water from our kitchen sink and dishwasher.  I only have to irrigate a bit more in the hottest months of summer, when they are extra thirsty as the fruit is filling-out.

If you've got heavy clay soil, I'd recommend that you plant those trees up at least 6 inches, and then gently slope the soil down, away from the trunk.  Make your watering moat quite deep and at least 3 feet away from the trunk, so that you can fill the moat with a lot of water, saturate the area, and then not have to water again for 4 days.

If that's too much work, a banana circle is made to be over-saturated.  Banana plants are thirsty camels, and piling a bunch of biomass in the pit at the center of a banana circle becomes this great absorbent sponge.  Further, as fungal networks colonize the banana circle, they work to break-down any soaps and residues that are in your grey water.

Mango would be your best bet and as others have mentioned, wet feet for fruit trees is a death sentence.
Dwarf trees are great for this sort of space, however they come with a but, dwarf trees don't live nearly as long as full size or even semi dwarf varieties.
The dwarfs make up for this short coming by producing fruits earlier in their lives though, which can be quite handy.

I would use the largest containers I can manage and set them up so you can water them as needed.
One of the things that will help greatly is if you aerate the water, O2 is a good thing in water, it actually does more for plants when O2 is abundant in solution.

The mango can be kept short with pruning and still produce fruits, you want a semi bonsai for this application, you will prune both roots and top no more than once a year or every two years if the container is large enough for that.


Redhawk

Around here, the only fruit trees that do well in saturated soil, are plums and pears. Everbearing strawberries can be set up to wick moisture from a damp spot. Not a tree, but they do produce fruit.