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Citrus in very large container/Mix question

Posted by andreajp z9 sacramentoCA (My Page) on
Wed, Sep 4, 13 at 9:32

I am getting ready to make a batch of gritty mix for two lemon trees that I recently purchased. The plan is to put these trees into VERY large pots and to make the pots their permanent home. I read somewhere on this forum that my pots would be very heavy if I added granite to my mix and that I could use perlite instead.

How important is Turface?

I have perlite, bark, and gypsum. I haven't purchased the Turface yet, but I will if it is necessary. I just need to know if it is truly necessary and if it will make the pots really heavy.

Thanks for your help. :)


Follow-Up Postings:

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RE: Citrus in very large container/Mix question

A...I did this exact drill with my dwarf lemon. I was not too happy...and it must be changed out. My large pot (terra cotta-about 15+ gal) was unbelievably heavy. It could not be moved. Secondly, it required water every day...even in my mild temps. The saucer was always full of water...and prevented further draining of the pot. It made my deck wet (and supporting beams)... constantly wet...not good. Your situation may be a bit different.


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RE: Citrus in very large container/Mix question

Gritty mix is designed to remove the perched water table in the pot yet hold some moisture in the bark and turface to be available to the plant. It is designed with the thought that roots of many plants require water AND air. A saucer would be almost totally incompatible with this design.

Granite will remain in the pot unchanged, at least for the life of the plant.

Turface will remain unchanged in the pot, at least for many years, probably decades. The substitutes may deteriorate much faster.

Bark will break down and will determine when you need to repot or replace you potting mix.

Perlite will break down much faster than granite. They both serve the same function in the mix - they take up space. I found mine breaking down way to fast to consider using it for a "permanent" planting.

I'm using mostly terracotta pots, which do let water evaporate out the sides. This means I want my mix to drain slower since the terracotta is helping remove excess moisture.

I did substitute pumice for some of the granite and turface in some larger pots to cut down on weight. Pumice is going to hold lots of water like turface.

I used the Gritty Mix as normal for my plants in plastic or fiberglass pots. My 8' tall by 4' wide Eureka Lemon in a 24" plastic pot with that mix weighs about 300 pounds so it is still movable.


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RE: Citrus in very large container/Mix question

I probably shouldn't have used the word permanent in the sense that I will root prune and repot the tree throughout the years, but the tree will always live in a large pot.

The pot I am using is 24 inches in diameter.

From what I am gathering, the terface is essential? A 50/50 mix of bark and perlite won't be enough to keep the trees happy?


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RE: Citrus in very large container/Mix question

Gritty Mix is made with the idea of no pieces smaller than 0.10" so that it has no perched water table. The granite just takes up space since no water or nutrients can penetrate and little sticks to the surface. The turface is broken calcined clay so it holds lots of water and nutrients. The bark also holds lots and is the only organic component.

You can get turface at John Deere Landscapes and there are several in Sacramento. I bought the Turface Pro League, John Deere Landscapes item 088205. It is more expensive than AVP but has a much more consistent size, with virtually no fines. The spec shows 94% larger than 16 mesh with 0% above 5 mesh. Only 1% goes through a 20 mesh screen. I think it is way cheaper for the material you use and I couldn't even imagine screening the pallet load that I bought. I paid $21.75 for each 50 pound bag.

The turface alternatives like Napa Floor Dry looked like a horrible choice. They might be acceptable for a few small plants where you are going to repot and replace the mix in a year or two.

Sacramento climate is much like mine so I think you will be likely to need more turface than granite like I am finding works for me.

The only good thing I've seen about Perlite is the lack of weight.

50 pounds of sand or gravel is 0.5 cubic feet. 50 pounds of Turface Pro League is about 1.25 cubic feet.


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RE: Citrus in very large container/Mix question

"weighs about 300 pounds so it is still movable."

Um, what? Who considers 300lbs to be movable??


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RE: Citrus in very large container/Mix question

some very strange comments and "facts" being given out here...I would advise going over some old threads on gritty...and gleaning info from a few experts like "Al".


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RE: Citrus in very large container/Mix question

Al has posted some fabulous info on container soils. I would suggest you look at more than gritty mix posts by looking over his posts on "container soils - water movement and retention". Lots of good info there, building on and doing a better job explaining the physics involved than what I learned 30 years ago from some potted citrus experts here. They were using fir bark, coarse sand or fine gravel, pumice, and fired clay pellets.

You should note that my suggestion for using Turface Pro League instead of screening Turface AVP will give you a smaller average size of the Turface component. Virtually none of the Turface Pro League goes through an insect screen. After screening one bag of AVP, I realized it would be a shocking amount of work and I would need to start with 30 bags.

My testing in clear cylinders gives you a small, but some, perched water table after draining for an hour. Inserting a toothpick will get you 10-15 drops of water out of a 14 oz container so the perched water table IS there. I'm using terracotta pots or a wick in plastic/fiberglass to remove that tiny bit of perched water table. It is almost certain that Al's Gritty Mix would be better than my gritty-ish mix in damp parts of the country.

I would suggest you consider your requirements and then do a trial to see what works for your conditions.

This post was edited by GregBradley on Wed, Sep 11, 13 at 12:05


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