What kind and where to find fine compost that can mix with potting soil for better drainage?

[Zboltman]

We have some large pots that the dirt appears to be too clay based and won't let the water drain.
This has led to the demise of a couple nice plant including a Jpanese Maple.
Going to re-do the dirt with pumice, coconut noir, perlite, sand and fine compost; if I can find it.

The question is, what kind of compost is fine enough for potting soil that will help it drain.
Where might I find such compost. (And what is it called...)

 

[Meadowlark]

One can very easily make their own compost or purchase it from innumerable sources...and then run it though a sifter...

 

[Zboltman]

One can very easily make their own compost or purchase it from innumerable sources...and then run it though a sifter...

View attachment 113634

Now that is a good idea. I have coconut mulch; Would that work?

 

[Meadowlark]

Maybe...never used it myself...make my own which is far superior to anything commercial.

 

[MiTmite9]

Any source nearby for rice hulls? Those work nicely to break up clay soil. Also try adding a bit of gypsum.

Gypsum: improves heavy clay soil by breaking up fine, compacted particles, creating a more crumbly (flocculated) structure that boosts air circulation and water drainage.

Rice Hulls: significantly improve aeration, drainage, and soil structure, breaking up heavy, dense clay by increasing porosity. Because they break down slowly, they provide long-lasting benefits, such as reducing waterlogging, improving root growth, and slowly adding organic matter.

https://www.youtube.com/watch?v=RdBnfmvD1Z0&t=449
Key Benefits for Clay Soil:

• Improved Drainage/Aeration: Rice hulls separate clay particles, decreasing waterlogging and creating porous soil, which allows for better oxygen transfer to plant roots.
• Preventing Compaction: They are a durable, lightweight organic material that helps prevent heavy clay from becoming compacted and hard.
• Slow Decomposition: Unlike softer organic matter, rice hulls last longer in the soil, providing structural benefits for a longer period.
• Nutrient Release: As they slowly decompose, they add silica, a beneficial nutrient that strengthens plant cell walls, which helps protect plants against pests and diseases.
• Soil Management: They are generally cost-effective, sustainable, and have a neutral pH, preventing issues with soil acidity.
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Best Application Practices:

• Incorporation: For best results, mix rice hulls into the top 6–8 inches of your clay soil, ideally with compost, to help with structural breakdown.
• Proportion: You can apply them heavily; a common recommendation for improving heavy soil is mixing in a generous layer.
• Mulch: In addition to amending, they can be used as a top-dressing mulch to help manage moisture and discourage weeds.