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  • Best Potting Mix for SIPs?

    For those of you who use SIPs and have tested and really worked it out over time:

    1) What do you find to be the best mix for SIPs?

    ​​​​​​2. Have you used Pro-Mix HP or BX?

    A) Is one better than the other for SIPs?

    B) Would you amend either in any way to make it better?

    ​​​​​​3. Mushroom compost: is this something I should be considering?

    In case it makes a difference, this is for mature trees in 5-gallon SIPs and I'm in zone 3 with a Jun-Sep growing season that is hot and dry.
    Zone 3

  • #2
    I had to scale the recipe down for the number of containers I used.
    Alan. Los Angeles area. Zone 10b (Sunset zone 24).
    Looking for: Boysenberry Blush, Hative D'Argenteuil, Ondata.


    • FigsNorth
      FigsNorth commented
      Editing a comment
      Thanks. That mix seems to resemble the Pro-Mix BX.

      How did you arrive at this mix being the best? Did you test many others?

  • #3
    Pumice is my secret ingredient for any mix that needs to wick water well. Put 25% or more pumice into your mix and it will both aerate your soil and wick water very effectively.
    Eric - Seattle / Sunset Z5 - W/L: Granato, Malibu Greek, Moellada, D’en Bota - Now offering my gritty rooting mix! https://www.figbid.com/Listing/Brows...er=pacnorwreck


    • WIFigger
      WIFigger commented
      Editing a comment
      Pumice is next to impossible to find in the Midwest. The closest place for me is a bonsai nursery in Chicago. Unfortunately I think it's something that's regional.

    • PacNorWreck
      PacNorWreck commented
      Editing a comment
      don_sanders I get it either from General Pumice Products online or Bonsai Jack as part of their inorganic bonsai soil.

      I know some bonsai enthusiasts buy it in bulk either from bonsai stores or as ‘Stall Dry’ from farm supply stores but have no direct experience with either of those.

    • Billmag
      Billmag commented
      Editing a comment
      You can often buy pumice at hydroponic grow shops

  • #4
    I love promix hp and bx…. But I bought this earlier this spring…. Less expensive, more perlite and top shelf. I’m into my 5th bale this season. Love it

    Guildwood Village - Toronto, Canada - Zone 6


    • FigsNorth
      FigsNorth commented
      Editing a comment
      Thanks for the suggestion! I checked it out online and noticed they add silicon. I never knew plants could use it. Only thing missing might be mycorrhizae, though I see they also sell a version with it (but it looks like the places I checked sell the version without). Do you add myco to yours or just forgo?

      Does it still wick well with the extra perlite?

      Cheaper sounds better, especially with high quality ingredients.

    • TorontoJoe
      TorontoJoe commented
      Editing a comment
      I don’t add myco. I haven’t noticed a difference.

      There’s still plenty of peat so it wicks great

  • #5
    I use a mix of 40% compost/40%peat/20% perlite/rice husks. It seems to work quite well for me for sips from 5 gallon to 50.

    Some users of straight compost from the past have loved it but I haven’t given it a try yet.
    Don - OH Zone 6a Wish list: Verdolino, Sucrette UCD, Rubado


    • #6
      Oh… I do really like mushroom compost… if you can include worm castings they seem to do wonders…. They can be expensive though
      Guildwood Village - Toronto, Canada - Zone 6


      • FigsNorth
        FigsNorth commented
        Editing a comment
        Maybe I'll look for it to test it. In truth I've never even seen what it looks like. I think I read it was wood compost or something. The only reason I asked about it was because I remember a grower (Bill's figs?) was using it for his SIPs.