Resurrecting this thread instead of posting a new one.
I have some year-old trees that I'm potting up from 1-gallon pots to
5-gallons for thickening & root development.
I was planning on doing Sifted Pine Bark & Grit for a cheap substrate. But I like to test my soils using a method I learned from reading a paper by
Heltsley. I made a sample mix and tested it, and it came back at 38% Saturated Porosity, but only 16% Field Capacity. The acceptable ranges (according to Heltsley, but I have no idea where he got them) are SP 25-45% and FC 18-28%. I had filtered all the fines out of the Pine Bark, and hence lost most of the field capacity. If I used this mix, I would be watering all day.
So I made a second mix using materials I have on hand (from my other tests). This time it was about 60% Sifted Pine Bark & Grit, with the remaining balance being Turface & DE for water retention. This tested at 36% saturated porosity and 24% field capacity, right in the money. All sifted to 2-5mm size.
But, and this is my question, should I worry about having all the substrate sifted to the 2-5mm size at this stage, or should I just go Unsifted Pine Bark and/or Spagham Peat Fines and add grit until the I get SP & FC in the right range? Because if I didn't have to worry about size, I could get my FC out from the fines of the Pine Bark or Sphagnum and I would not need any Turface or DE for moisture retention.
I hear the fines negatively impact drainage, which is why I sift them out. BUT, this isn't a bonsai pot either, and they had been growing their whole first year in 80% composted pine bark, fines and all.
Thank you!