We in S.C. have low pH, so I have never had your problem. Your plans sounds like it will work. You can use surfer to lower the pH also.

If you are going to irrigate with either well water or municipal water, you will need to find out the pH of this water supply. If the water has pH much above 7, then it will take periodic soil testing, and likely application of agricultural sulfur, to keep the soil pH at optimum. However, if you are able to use a rain barrel, or surface water for irrigation, then the soil pH should remain stable over time.

Thank you both for your feedback! This is the latest mix I have come up with:

30% Florida Peat
30% Small Pine Bark
25% Florida Clay
8% Coir Pith
3% Canadian Peat
3% Allgro Compost
1% Perlite

I don't want to put too much perlite since I heard it will get crushed and settling will occur since the hole will be 5 feet deep.

Thanks,
Adiel

What is your current soil pH and what do you want to get to?

If there is a significant difference between the two, you might want to rethink your plan. Altering soil pH is not a permanent 'fix' - all soils have a buffering capacity to varying degrees that will gradually return pH to the status quo. Attempting to change the pH in a specific area will be an ongoing process. And you do have to take into consideration the pH of irrigation water as well - that will also play a significant role in how long term any adjustment will be.

Amending an area as large as that is problematic at best. It sounds as though you are just going to be digging a giant planting hole and filling with new soil. This is not advised for any number of reasons. There will be differences in soil texture between this planting area and the native soil that will impact drainage and water percolation. The roots of the tree will eventually (and faster than you expect) grow outwards beyond the pH-adjusted planting hole and then what happens when they encounter the higher pH conditions? And it is never a good idea to dig a planting area for a tree deeper than the rootball. Settling is inevitable, especially with an imported soil mix that includes a high proportion of collapsable, fine OM particles like the peat and compost. When (not if) that happens, you risk the viability of the tree, all other factors being equal. Too deep of planting is the kiss of death for many plants. (Perlite is a volcanic rock and will not crush easily - that is the least of your worries re: settling)

If the change required for pH is not huge, I'd use something to alter existing conditions - like sulfur - before attempting to replace the soil. If the change is large, then you may be much better off growing the plant as a container specimen where you can tailor the container soil to the plant's needs rather than trying, most likely unsuccessfully, to change the existing soil pH for long term results.

There is a great deal of validity to the phrase "right plant, right place". Attempting to grow a specific plant ill-suited to existing conditions, whether it be climate, light, soil pH or drainage, is only going to result in a lot of frustration and disappointment. The way to get around this is container culture, where you can far more easily make any necessary adjustments.

re: eric's comment on irrigation, you would be wise to read up on bicarbonates in irrigation water. Much of Fl's well waters, municipal or not, have bicarbonate issues that can present real problems that will be even bigger if you do what you plan to do. The solutions are not simple. Check out the link.

I strongly agree with the points Gargwarb made, amongst them, settling issues after planting, roots extending past the modified soil. I didn't notice what you are planning to plant but if it is a fruit tree, beter go with one on full dwarfing rootstock, at least the root system will be as confined as possible.

Here is a link that might be useful: FL waters

Thank you everyone for your comments! gardengal48, I have a question, what do you think would be worst for a tree that requires low ph, planting it in 6 inches of soil and the rest down limerock where it would have no chance at all to survive or removing the hard limerock and replacing it with lower ph soil where it would be able to do better? I am really weighting your advise but I feel that if the plant is to survive at all, at least I would make it feel more at home?

Also, in regards to watering, I will be using a rain barrel for this tree with low ph water. I will not be using irrigation. I will also plan on mulching when needed with pine straw to maintain low ph.

Thanks Again Everyone,
Adiel

I forgot to mention:

Current PH: 7.0

Want to get to PH: 5.5 - 6.0

Thanks,
Adiel

What kind of tree are we talking about? And where exactly are you located? Given your choices and the change in pH you require, I'd probably opt for a container. Given you have a limestone base under the topsoil, I just don't think you are going to be able to keep the pH within the desired range very successfully. And personally, I would not go with digging out and replacing the soil with your mix.....it is just not a practical or efficient solution, primarily for the reasons I already outlined.

And FWIW, mulching with pine straw will have virtually no effect on pH. That it does is pretty much a gardening myth :-)

I always dig tree holes bigger & deeper then the root ball.
I amend the hole,because this is the last time you will do this. I turn a 4'X4' area for small trees/bushes & a 8'X8' for standard trees,turning is abut 8" to 10" to kill weeds & make room for surface roots. . I water the hole in 24 hours before planting to settle the loose soil & plant the root ball a little high. I mulch the bed, be careful, if you cover the graft on some fruit tree, it will root. On a dwarf tree, you could end up with a standard. I have more open land then most. I over do the room & digging, because I can. My blueberries are 9' to 15' apart. Even more for,Apple,pear,apricot,cherry,plum, grape,muscadine, & fig.
I get my mulch plan from Lewis Hill "Fruits & berries for the Home Garden". Every fruit owner I know has a copy or borrows mine.

Thanks for the vote of confidence Michael, but that wasn't me, it was gardengal.
But for what it's worth, I too think she nailed it.

As usual, Pam (Gardengal) has offered excellent advice. If the pH your plant prefers is significantly different than the soil in the surrounding landscape, you'll forever be fighting an uphill battle to maintain something favorable. It's always a good idea to choose the right plant for the right location - makes life much easier. Plants stressed by nutrient issues are going to be much more susceptible to to stresses attributable to any one of a large number of other potential limiting factors - drought, drainage, temperature extremes, insects, disease .....

Al

gardengal48, the fruit tree I am going to plant is called Mangosteen. I am aware that it does NOT grow in the United States. It is an ultra-tropical. There is only one tree growing outside and it is in Bill Whitman's house in Miami also. Whew!, having gotten that out of the way, I will continue with my project. Here are some reference material from Julia F. Morton regarding this tree:

[begin of quoted material]

Soil

The tree is not adapted to limestone and does best in deep, rich organic soil, especially sandy loam or laterite. In India, the most productive specimens are on clay containing much coarse material and a little silt. Sandy alluvial soils are unsuitable and sand low in humus contributes to low yields. The tree needs good drainage and the water table ought to be about 6 ft (1.8 m) below ground level. However, in the Canal Zone, productive mangosteen groves have been established where it is too wet for other fruit trees in swamps requiring drainage ditches between rows and in situations where the roots were bathed with flowing water most of the year, in spite of the fact that standing water in nursery beds will kill seedlings. The mangosteen must be sheltered from strong winds and salt spray, as well as saline soil or water.

...

Culture

A spacing of 35 to 40 ft (10.7-12 m) is recommended. Planting is preferably done at the beginning of the rainy season. Pits 4 x 4 x 4 1/2 ft (1.2 x l.2 x l.3 m) are prepared at least 30 days in advance, enriched with organic matter and topsoil and left to weather. The young tree is put in place very carefully so as not to injure the root and given a heavy watering. Partial shading with palm fronds or by other means should be maintained for 3 to 5 years. Indian growers give each tree regular feeding with well-rotted manure 100 to 200 lbs (45-90 kg) and peanut meal 10 to 15 lbs (4.5-6.8 kg) total, per year.

[end of quoted material]

As you noted, Julia mentions creating a pit of 4 x 4 x 4 1/2 ft and filling it in with organic matter. Please let me know your thoughts on the preparation. I am definitely taking into account your advice also.

Thanks,
Adiel

ps: Please don't ask me why I am going to plant this tree. :)

References:
http://www.hort.purdue.edu/newcrop/morton/mangosteen.html

You are planting the tree because you want to - no more explanation than that needed!!

Depending on your soil conditions, digging a 4x4x4 or more pit is A) way too much work, B) putting the tree at severe risk of settling, C) potentially creating just a 4x4x4 bucket of enriched soil that will retain water and not drain properly and D) creating interface issues that can hinder establishment, alter water percolation and since pH is a factor, create an unnecessarily attractive but limited environment so that root development may be impacted. FWIW, the planting advice that you quoted pretty much goes against all current accepted planting practices.

Why not just plant it in a container and simplify your life considerably?

Thank you gardengal48. I don't mind part A. :) Part B, C and D are definitely an issue. (And I have to decide fast since the backhoe guy is suppose to come this Thursday!) I would say that Julia F. Morton had good advice, but maybe she left out certain soil considerations how you mentioned? If you were giving the task of planting such tree in such soil, how would you approach this? Would you just put the tree in the ground and walk away?

Thanks (Again),
Adiel

Garden, oops, Gargwarb: you're welcome for my boo-boo. You 2 both have much to say that I agree with, in that regard you sound alike :)

Methinks the OP is pushing a rope really hard planting in the ground and destined fail but alas, we all fail at times and sometimes have a glorious time doing it!

When I was working in FL years ago I had a chance to visit a commercial tropical fruit orchard near Homestead, they had a most bizzare way of planting trees - Step #1, with a ditch witch, cut a series (I forget the spacing) of parallel trenches appx. 1 - 1 1/2' deep, several several hundred ft. long, then cut another series of trenches perpendicular to the first set, same length. Step #2, plant the young trees at the trench intersections and back fill the trenches.

Now this may seem strange but wait, it gets even stranger, the "soil" is Marl, basically ancient sea bed. To most folk's eye the Marl is nothing but a sheet of smooth limestone and the material coming out of the ditch witch is rubble about 1-2" in size. I saw the orchard many months after Hurricane Andrew blew through and ripped all the trees out of their trenches, roots and all. The trees were righted and root systems placed back in the trenches and the trenches back filled with the Marl rubble. You'd have never known what had happened! Needless to say, the tree root systems never grow anywhere but the trenches.

If you think that's bizzare, go visit one of the tomato farms down there and see how they grow maters in Marl.

I am usually annoyed by persons who say go look somewhere else but occasionally I do just that myself. The 8X8X5 dimensions given in the OP made me think that maybe the people at Container Gardening would have some good suggestions as they have some rather serious soil talk there.

If you were giving the task of planting such tree in such soil, how would you approach this? Would you just put the tree in the ground and walk away?

I thought I made that pretty clear but I guess not :-) I wouldn't plant a tree that needed such specialized conditions in a soil that could not provide them. I'd grow it in a container where the conditions can be easily tailored to the tree's needs.

Thank you everyone for your contributions. I have made a couple of changes to my original plan based on your suggestions:

1. The limerock removed will only be 3 feet down. (The hole will now be 8'x8'x3'.) Instead of 5 feet down.

2. The mix of the soil ordered will contain more clay (and less peat and pine bark) to cope with settling a little bit better.

3. The tree will not be planted right away. This will give time for the soil to settle and acclimate.

4. I will be using a rain barrel with drip irrigation to ensure constant moisture and low ph. (As opposed to using well water which contains high ph in florida as mentioned above)

5. I found new inspiration in a thread mentioning Bill's Mangosteen and how he used a similar approach. (He used much more soil than me since he did his whole yard. He purchased 600 truckloads of soil!):

http://forums.gardenweb.com/forums/load/tropical/msg061009393611.html

I will let you know how it goes in a couple of months!

Thanks Again for everyone's contributions,
Adiel

I found new inspiration in a thread mentioning Bill's Mangosteen and how he used a similar approach. (He used much more soil than me since he did his whole yard. He purchased 600 truckloads of soil!):

Ahhhhh!! Therein that statement lies a HUGE difference. It is one thing to change or amend the soil in an entire yard or very large planting area (removing the old or just raising the existing soil level) and simply amending or altering the soil in what amounts to just an overly large planting hole. A pit in the ground will remain just a pit in the ground, surrounded by soil of different structure, texture and chemistry and prone to all the negative issues a heavily amended planting hole is likely to encounter.

It's a significant distinction and I don't think you can consider the approaches at all similar :-)

I know he changed more soil because he had more money. I will try to work with what I have. I am sure if I do things right, everything will work out good.

I will let you know how it goes in a couple of months!

Thanks Again for everyone's contributions,
Adiel

Good try, Pam. ;o)

Al

LOL! Thanks, Al :-) Yep, guess it's time to give up and bow out of this discussion.

As my ex used to say in situations like this "you buy 'em books and buy 'em books and all they do is eat the pages!!" ;0)

gardengal
I have tried not very successfully to grow blueberries in raised beds over clay. Good old michigan blue clay.Regardless of how good , including ph , the soil in the raised beds there was a problem once the roots came in contact with the native soil . And even though i made drain holes the berries lasted a couple of years then died.I think they developed a root rot caused by poor drainage and the clay beneath the good mixture retaining standing water.I think these are the types of results you are concerned with.
I think a completely independent container with good mixture would do the trick.Before i moved here I grew blueberries in sandy loam and they were great.There was a lot of good discussion above. Happy soil building Johnny

adiel,
best of luck with your quest

Thanks darth_weeder. The progress is going very good. I also picked up Bill Whitman's book, "Five Decades with Tropical Fruit"

http://www.amazon.com/Five-Decades-with-Tropical-Fruit/dp/0971140200/ref=sr_1_1?ie=UTF8&s=books&qid=1294245479&sr=8-1

He accomplished what many thought was impossible. I was reading his book last night and I am on the right track (thank God). That book is truly a diamond for anyone attempting to grow tropical or subtropical fruits. I actually drove to Fairchild Tropical Botanic Gardens and picked up a brand new copy for $40! (Cheaper than amazon and they should have phone orders in case someone is looking for a copy) He, like Julia Morton, also mentions of replacing a big area with acidic soil and removing the lime rock for the Mangosteen. If the tree I plant can produce one single fruit in 10 years, I feel something has been accomplished, also I am hoping to contribute something to other people interested in planting Mangosteen trees in a subtropical climate (and maybe even in colder areas with a greenhouse). I am going to setup a blog soon to show the progress and will post a message on this thread when it is ready.

Thanks,
Adiel