Hello:

I'm searching to find out what the best combination of ingredients for a potting mix is. I have some of the standard potting soil, but I've read through a few threads here and there seems to be a consensus about CHC. What proportions of ingredients make a good mix?

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Thanks David.

Dean,

I would stay away from CHC. Use a good quality professional well drained potting mix.

This link might help a bit: link

Good luck!

Personally, In my opinion with 20 years experience growing containerized citrus, I find potting mixes using ingredients such as CHC, Cedar or Pine bark chips, to be an outstanding excellent medium for containerized citrus trees. Even cedar shavings, as used by 4-Winds Growers, works well, but unfortunately shavings have a somewhat limited life span. THE NUMBER ONE (#1) most used potting mixture WORLD WIDE by commercial tree nurseries is 3 parts pine bark, 1 part peat moss, and 1 part sand.The reason commercial nurseries use pine instead of CHC or cedar is because pine chips are extremely inexpensive, and readily available in huge quantities. Pine, Cedar and CHC provided much the same benefits, but Cedar and CHC have a longer container life. Hard woods chips are not recommended due to having high levels of manganese. Dean the best of luck with your tree.- Millet (941-)

Thanks everyone.

Pine bark, particularly larger particles, such as 3mm to 5mm, and more so 5mm to 10mm create structure and airspace. They are pretty stable over time. Pine bark fines in the mix may tend to break down more in pots, but probably far less than pine sawdust, or other timber wood wastes.
Composted pine bark, ending up as a proportioned mix of particles and fines would be the most common pot mix used in Australia.
(this may change as "waste pinebark" gets diverted into on site bio energy/clean fuel projects)

Peat increases the water holding capacity, and adds other benefits, the % added balanced against the% pine fines in the mix, and cost of peat.
Coir peat has the advantage of increasing the water holding and re wettability of the mix(other peats can get water repellant). At the same time, coir doesn't lower the % airspace of the mix to any degree, due to its structure.

Sands add ballast and aids re wettability, a good particle mix would be mainly around coarse table salt to sugar sizes, as this creates a level of inert smaller particles in the mix which can't degrade.

These pine bark based mixes also have their share of problems: Water repellance, low level toxicity, heating up in storage, proliferation of wood rotting fungi, Nitrogen consumption(NDI) by the mix itself.

Coir based mixes eliminate some of these problems, and can be superior in some factors.

As with most things in life, there is no absolutely 100 percent perfect potting mix. All mixes, every one of them, come with a few drawbacks. The aim is to create a potting mix, that provides for as many of the requirements needed to grow a good container plant, while having the fewest drawbacks. . As far as using a "good quality professional well drained potting mix," that is exactly what the potting mixes we have been writing about are: = they are good quality mixes, professional, and well draining. - Millet (941-)