Paully,

Your growing mix is going to be a compromise between what is "best for your tree" and what is "best for you". If you have the ability to water everyday, a loose soil works great. If your schedule is more restricted, you may want a mix which will hold more moisture.

Mine is a loose mix. I try to use the same mix my trees, regardless of age or container size. I do not use peat, vermiculite, manure or humus in my mix. My goal was for a loose soil (requiring frequent waterings) while being stable (not needing to be replaced) for at least two years.

Remember, you are responsible for providing all of your trees needs when it is in a container. You can ask 12 of us in here what we use and you might get 12 different answers. None of them are wrong, it is what works for us. I've grown a couple of trees in nothing but mulch, and they grew nicely. Whatever you choose, consider it a start point, and understand you will need to make modifications down the road. What is maximized for my conditions in Houston may not be close to the conditions you face where you are. Modify your mix as needed to incorporate what you see happening with your trees.

~james

Here is a link that might be useful: Container soils and water in containers

Good advice by James and the link references an excellent thread featuring advice from Al (Tapla), a master gardener and bonsai enthusiast. A couple of years ago, Al was kind enough to correspond with me regarding his ideas on container soil. Following is my version of a potting medium for figs, drawing on some of Al's principles. There are a number of approaches that will work.

Soil Recipe for Figs

3 Parts Pine Fines (2 cu. ft.) = about 12.9 dry gallons

1 Part Turface (.66 cu. ft.) = about 4.3 dry gallons

1 Part Perlite (.66 cu. ft.) = about 4.3 dry gallons

1 Cup of Powdered Dolomitic Lime

Osmocote 13-13-13 Fertilizer (1 cup = 244 g., 28 g.= 1 oz.) Â Recommended Application Rate for medium sensitive nursery stock is 6.5 oz./cu. ft. = 182 g./cu. ft. 182 g/cu. ft. x 3.32 cu. ft. = 604.24 g. total = about 2.5 cups of 13-13-13 per batch of 3.32 cu. ft.

ScottÂs Micromax Micronutrients- Recommended Application Rate for nursery stock/pot plants is 1 oz. (about 30 g.)/cu. ft. (1 oz. = about 4 level teaspoons.) 3.32 cu. ft. x 30 g./cu. ft. = 99.6 g. or 12.4 level teaspoons or slightly over 4 level tablespoons per batch of 3.32 cu. ft.

(Volume of Soil Batch is about 3.32 cu. ft. or about 21.3 gallons  I mix it in a large wheelbarrow.)

**Note** This potting medium drains well and promotes root aeration but may require daily watering in hot dry summer weather.

Mine is a variant of Al's mix. One of the reasons I like this mix is that I can water it everyday. I water in the afternoon to cool the roots down. This may not be so important in Zone 7 as it is in Zone 9, however, one gets the idea that there are a number of factors (weight, type of plant, growing environment, budget, life of the growing mix, watering schedule, etc.) to consider when building a growing mix.

I am potting up a bunch of trees tonight in NJ. I am not planning on using exactly the same mix as I use in Houston.

~james

I also use a variation of Al's mix.
My basic recipe for my potting soil is :
(my scoop is approximately 4 heaping cups)
3-4 scoops Pine bark (chipper ground from nuggets or mulch if available)
1 scoop sphagnum peat moss
1 scoop pelletized lime
1 heaping scoop Turface
1 scoop coarse Granite growers grit
1 scoop Perlite
For every 5x of the above mix I add:
1 & 1/2 cups Ironite
1 heaping cup Osmocote
1 level cup Soil Moist crystals

The two figs I potted in it did great, very good root development and both produced figs last year.These two were my first ones. I used some of the leftover soil for some other pottings (tomatoes, basil, oragano, even grape vine cuttings). I have made up the same mixture to use this year on my new figs from Paradise.
I plan to modify it some to use on my new blueberry plants(no lime, equal peat to pine bark, some sulfer granules and Hollytone instead of Osmokote).
I can't say for sure it is the "Ideal" potting soil but it drains well, has good aeration and so far everything I have planted in it seems to grow well.

Woody.

Furo - Just a thought - you may wish to skip the supplemental iron (Fe) in soils with a substantial part being conifer bark. It's usually always available in adequate amounts. Fe in anything greater than a 2:1 ratio with manganese (Mn) can prevent Mn uptake. This causes what most perceive as the same chlorosis (even though it's different) as an Fe deficiency and often prompts the addition of more Fe. Ironite also lowers pH which increases the possibility of Fe toxicity.

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Wow - I'm glad to see you guys are happy with a variation of the same mixes I use. ;o) You've done such a good job of addressing the original question, I don't have much specific to add to it, but I have a few generalities & some musings.

Container soils are only "ideal" for a very short time. Containerized plants and the soils they are growing in are in constant flux. As the plant grows and needs more water, the soil is breaking down (hopefully slowly, too) and holding more water. Ideally, we would start with a very highly aerated soil with small plants and end at repotting time with a mature plant in a soil that holds more water, but still an adequate volume of air.

The growers above recognize that, and are striving to build that mix. They recognize that it's unlikely to be found in a single bag.

Still general information, and measurable: An ideal soil will have about 60 - 70% total porosity (air and water) with at least 30% air porosity at container capacity (this is the level of soil saturation after soils are completely saturated and then allowed to drain. Just as drainage stops, soils are at container capacity. There should still be 30% of the total volume of the soil occupied by air at that time).

Al

I had hoped you would join in on this Al. I added the Ironite not so much for the iron but for the other mineral content, it was the mineral supplement available at our local gardening store. I added a large quanity of pellitized lime to offset the acidifing effects of the Ironite. Have not seen any signs of chlorosis, I assume it is possible that with the high flow rate of water in my mix that most of the effects from the Ironite have been flushed out (the grass below the cinder blocks that I set my pots on grew REALLY well last year!) This years new growth on my figs is looking good. Will keep a close eye on them though. Is there a mineral supplement that you would recommend for adding to soil mixes or would it be better to just go with what is contained in the pine bark naturally and what may be in the Osmocote?
Mixing up a good potting soil is like baking a cake, there may be basic ingredients and methods but getting advice from a better chef is always welcome and can only improve the final results.
Woody.

Using a fertilizer that has the minor elements should be adequate for almost all container situations. For acid lovers, an acidifying fertilizer is in order, but for figs, a generous helping of dolomitic lime will help.

I add an insoluble granular micro-nutrient mix (Micromax) when I initially build a soil, and then as the effects diminish, I switch to a soluble supplement (STEM) that I apply with each fertilizer application.

These supplements are usually hard to come by in small quantity & they're expensive when you need to buy 50 lb bags. If you decide you want to try them, I'll put you onto a source - if you contact me off forum.

Al

Many,many,many thanks to all for the info on potting soil mix. It is so pertinent in container culture for the overall health of the plant(s) & our health when we consume those sweeties. Looking forward to my first yr as a figgie newbie. Right now one of my plant has more than 15 fruits--about thumb nail size.
Paully