Mangosteen Advice Thread

[roblack]

I'm looking for some ideas on how to proceed with my mangosteen project. Since South FL soil is full of limestone (pic below shows just how bad. It is solid limestone at the bottom of that hole, had to use a jackhammer to get that deep), I was thinking of creating suitable soil, and then placing the plant above the amended soil, on a raised mound secured by rootsaver pots that will be attached to one another.

Just had this hole dug. Thinking I should line it. The hole is roughly 43 inches diameter by 2 feet deep. Calculates to a little over 150 gallons.




How should I line it? Should I leave holes for drainage? Are there any liners with copper in them, and if so, are they safe to use?

Also, any advice on soil composition is appreciated. "deep rich organic soil, especially sandy loam or laterite" is recommended on the hort.purdue.edu site. How might I achieve such soil?

Here is a pic of the tree

[SoCal2warm]

That alkaline limestone soil is likely going to leach into your more acidic loamy soil over time.
Also, the roots of that mangosteen are eventually going to expand out in all directions and reach the limestone.
Perhaps planting the mangosteen on a slightly raised mound over the hole? And maybe surround the edge of the hole with a soil partioner? (around the sides, not the bottom)

I'd make sure the hole is at least 30 inches wide and 30 inches deep (preferrably 36 deep if possible). Next you may wish to sprinkle some alum (garden store for lowering pH) at the very bottom of the hole before you fill it in, so if for some reason in the future the ground does become completely saturated with water, the alum will leach in with the limestone and you won't get a net alkalinity in the soil. Also I would mix in a lot of decaying compost into the soil, possibly also a little peat moss, because that can help slowly release some acidity as it breaks down.

Maybe plant a banana nearby the mangosteen to help provide some shade. Then you can always hack the banana back later if the mangosteen gets really big.

The hole is roughly 43 inches diameter by 2 feet deep.

I know it's really difficult digging down in that ground, but I'm thinking 2 feet is not going to be deep enough.
First, the roots are going to want to go down much more than that after 2 years. Second, you want a nice buffer layer so if any limestone alkalinity starts leaching in, it's not going to immediately move into the layer where the roots all are.
Keep in mind there have been many attempts with mangosteen in Southern Florda and most of them have failed, likely due to the limestone soil. You want to go to greater lengths than the average person would have been likely to go to.

How should I line it? Should I leave holes for drainage?

Around the sides, not the bottom.

Maybe add a layer of alum and/or peat moss at the bottom.

Also, any advice on soil composition is appreciated. "deep rich organic soil, especially sandy loam or laterite" is recommended on the hort.purdue.edu site. How might I achieve such soil?

Get the more expensive potting quality soil, maybe something organic.

Some of the cheaper landscape soils are lighter weight, have a lot of wood chips in them, and aren't really rich or good at holding moisture. Don't get those.

Maybe think about starting a compost pile.

I would mix in 30-40% compost with a high quality dark black potting soil.

[roblack]

Thanks SoCal2warm! All of that is very helpful. Going to get the jackhammer back out here and see if we can get down to 3 feet. Plan on building up a mound and elevating the tree about 1 -2 feet

Will line the sides, and make amendments as recommended.

I like the banana tree idea. Have a nice sized mysore in a pot that's begging to go in-ground. It will also be surrounded by jaboticaba, carambola, surinam cherry, and passion vines.

While the tree has been getting some direct sunlight, it is probably 4 hours or less.

One citation showed trees "flourished" with annual rainfall of over 105 inches, and good soil. Going to try to mimic this; create a misty rainforest environment.

Know my chances aren't great in terms of getting it to fruit. It is fun growing, and is the prettiest tree of all the garcinias I have. If it fruits sometime in the future that will be a bonus. Kind of like playing the fruit lottery.

More ideas please!

[skhan]

I wanted to do something similar whenever I buy a new house, so I've been thinking of a few ways to achieve this.
I basically wanted an area I can plant acidic soil loving tropicals.

Here what I got so far:
Clear out as much of the existing soil as possible, maybe 2 ft deep but as wide as I can afford. 3ft would be better but I wouldn't go deeper. (renting a bobcat might be the only way)
Use the existing soil to create a mound around the excavated area.
Dump a load of tree trimmer mulch in and wait a season for it to turn into rich soil.
Test ph and adjust with sulfur.
Somehow mix sand, charcoal or some other medium into the soil to help drainage if necessary.
Plant subtropical acidic plants on inside edges as windbreaks and soil bell weathers (jaboticabas, Eugenia, Starfruit, Bananas)
Plant tropicals on the interior (mangosteen, pulasan)
Add a generous layer of mulch on top.
I'd probably go through the trouble or having an instant water heater connected to that sprinkler zone to keep the temperature regulated. (set to warm)

To maintain
Add sulfur to correct ph, yearly
Add mulch to keep building the soil. 

[dwfl]

Cold fronts (and the occasional hurricane) is biggest climate concern Rob. It won't take temps in 30s F to do damage. Temps in 40s F can do damage. You can also see major leaf desiccation a bit after a good cold front blow through. The tree grows slow enough as it is, you dont want damage occurring and setting it back. I would construct a simple frame around the tree that you can wrap with a layer of poly and frost cloth for when those annual cold fronts blow through.

[roblack]

Thank you Skhan and Dwfl. 

I agree, changing out the soil around the hole would be beneficial. I like the idea of a mound around the area as well.

As for the weather during cold spells, your plan should work well dwfl. I could devise a makeshift green house just by laying plastic over the neighboring plants and mangosteen. It has already tolerated temps in the hi 30's without showing stress, but keeping it warmer would certainly be better. 

I want to put a sprinkler right next to it, to keep moist/humid but also to keep warmer on cold nights. 

[Kada]

I would also worry about raised mou.d plants on rock with high wind areas, seems like a near impossible lo.g term feat.

[roblack]

Yes Kada, a tree on a mound will be a bit more vulnerable. However, wind is a lower concern of mine. Even when we've had tropical storm and hurricane force winds (cat 1) cutting through, everything survived. Some taller trees were bent over, the shorter ones were mostly below the ripsaw of wind. Will do what I can to provide extra protection and support, but will just have to roll the dice.

As long as the neighboring trees are taller, I think it will be fine. It is in a nice little clearing, surrounded by wind breaks in all directions.

Won't let it get too tall, and will trim more if a bad storm is approaching.

This is a fun experiment. While eventual failure is quite possible, having a good time with the project.

Thank you everyone for the thoughtful posts and info! All of this helps a lot.

[SoCal2warm]

Add sulfur to correct ph, yearly

Sulfur (we're talking about elemental sulfur, yellow, not sulphates) is good at keeping the pH down over time but I would worry about sulfur (again talking about elemental yellow) not being good for the roots (especially since mangosteen roots are notoriously sensitive). There is a chemical reaction in alkaline conditions leading to sulfites or thiosulfites.
It also might impart a less than pleasant flavor once the mangosteen does eventually fruit.

[SoCal2warm]

Part of the reason I suggested a mound is because the alkalinity in the soil is unlikely to leach up above the soil line into the mound.

If the alkalinity is creating a nutrient uptake issue, the roots will still be able to pull in those nutrients from the mound.

Maybe a 10-14 inch high mound, with the edges of the mound just a little wider than the hole.

Try to put the other plants around it so it is more likely to recieve morning sun. And consider the direction of the prevailing winds and try to put something in its path to block it.

[roblack]

Thanks SoCal2warm. Going to scrape as much of the topsoil as I can around the perimeter of the hole, down to the limestone. Then will line the sides of the hole. Do you think I should also line the newly uncovered limestone on the perimeter of the hole?

Then, will add dirt, mixed with sand and perlite. Lots of peat. Will water, and then add dirt as it settles over the course of weeks and months.

Will add more organic soil to the top, building a mound 18 - 24 inches high. Then, will encompass the mound with rootsaver pots, attached to each other.

Thinking of placing a few (3 -4 ) pvc pipes with holes drilled in them, down into the hole. Then, could add fertilizer or ph enhancements via the pipes to the lower roots and area near the limestone bottom. Can this work well and any advice?

In the springtime, will place the mangosteen tree in the middle of the mound, release the roots from the pot its in, and fortify with dirt and then mulch and water like crazy.  Will set up a misting system, and water daily (probably multiple times daily), until feel comfortable that it has acclimated well.

Not too worried about the transplant. The roots have not shown to be as sensitive and finicky as many report, as I've broken the tap root during previous transplants with no noticeable stress. The key might be in making sure that the entire root system is well watered and healthy, so the plant does not overly rely upon the tap for nutrients.

[roblack]

Also, will lay a 3 inch+ layer of pebbles (not limestone) at the bottom of the hole before adding dirt. Hoping this will mitigate the leaching of alkalinity upwards from the limestone, and help hold the liner on the sides in place.

[roblack]

Here's an update on my mangosteen project:

It's been a few years, and I've largely neglected this project. Occasional watering, and some experimentation with fert, but not much. Dry winter has wreaked havoc, and tree was looking like crap.

So I started watering and hit it with some good ole Oscmocote.

She's bouncing back!



Lots of new growth



Very motivated to start babying it.  New growth has triggered hope.

[shot]

It is bouncing back good.Now hit with some 138 iron while that tissue is expanding.

[brian]

That looks line a comparatively huge container, is the intent to minimize repotting?  Last time I repotted a mangosteen seedling I was surprised how little root volume it had, I probably could have waited another year or two before it got root bound

[roblack]

Will hit with iron shot, thanks! What is "138 iron?"

It is actually in ground. The root saver pot pieces were to keep the mound in place. I dug a hole into limestone, lined it and painted with copper paint, and then filled with sand and dirt and stuff. Tried to give it a lot of lower ph substrate to work with.

[brian]

Ah, gotcha.  You had my doubting my container

[cbss_daviefl]

Sequestrene 138 Fe is a brand of 6% fully chelated EDDHA iron

I put one of my large potted mangosteen in the ground a few months ago and it has been dropping a concerning number of leaves. I put up a shade cloth to shelter it on three sides but is still getting burned up top.

[Seanny]

Rob, have you tried Florikan 12-6-6 npk pro or similar?
Suppose to be more acidic than Osmocote.

[shot]

https://www.pestrong.com/1354-sequestrene-138-fe-chelated-iron-eddha-sprint-138-5-lb.html

[roblack]

Thanks cbss, shot, and Seanny!

My tree gets a lot of shade. There are several trees hanging over it. Gets some direct light, mostly midday. The rest of the day is dappled.

I think it needs consistent water. Doesn't like getting dry.

Gonna feed it and water it and take good care of it now and see what it does.

[TropicalFruitHunters]

Looks good!  You've done better than most.  Keep up the TLC!