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511 mix questions

S k
2 months ago

Good afternoon all,

Thank you for this forum. I have read through many threads regarding 511 and learned so much regarding PWT and soil composition. It seems to make sense given my experience/frustrations with container gardening.

I wanted to get some input on my specific set up and concerns I may have discovered. I have had trouble locating the park fines in my area. I am in phoenix az and this seems to be a sorta doable for replacement.

Gardentime 2 cu. ft. Pathway Bark GT 00023 (

I have used it in gritty mix and it seems to be doing well for my cacti in them. I saw someone else mention this bark on another 511 thread and it seems to match up with Al's 511 pic that he uses frequently show his 511 mix.

Back to 511.

At first when I sifted the bark that I linked above, I had used a sieve of 1 mm/0.04 inch. I then realized that it had too much dust for my liking, so I resifted it with sieve measuring 3mm/0.11 inches. (I got on amazon, used for bonsai). This left me with little to no dust.

Because of many failed attempts of different potting mixes in the past I have tried, I have lots of old soil with perlite, pumice and peat/coir in them. I don't want to throw this away so I have sifted with the 3mm/0.11 in sieve to save what I can. This leaves me with perlite, pumice, and minimal forest twigs/bark bits from other mixes. I plan to mix this in to the 5-part Pine bark, 1 part pumice/perlite mix I have already premade. The leftovers were stored in various fabric grow bags and some plastic pots.

I am not using any peat/coir because I have had many issues with water retention in the past that I would almost rather make a middle point between this and gritty mix, something like 5 parts pine bark mulch and 3 parts perlite/pumice. I tend to overwater (I have doubts regarding this, maybe confirm?) but even when Al mentions the PWT and the idea that people should be able to water freely without worry of killing plants, I still fear I will drown my plants because of watering habits. Note: When I water using my garden Nosel on shower setting, I normally water maybe 5 seconds max on a plant, which does not seem like it would be overwatering. Even in 110 plus degree days it may be 3 days until I water again. When I hear people have to water 1 or more in a day, it seems preposterous to me given my history.

1) Is the 5 part pine bark 3 part pumice/perlite a doable mix given this idea? I do have a jalapeno that is in a 511 like mix and it is hanging on. Most of its leaves are gone but I think it should bounce back once it begins cooling down.

2) Does my watering seem off to you?

My second area of concern is that today I was finishing preparing new pots for planting I will do in a few weeks. I took some 5-1 mix I had premade a few weeks ago and put it in new pot. I then mixed in a bit of the leftovers of pumice/perlite/bark that I saved. All the grow bags were fine. In one of the plastic pots where I had stored the 5-1 mix, the top of the mix was fine, but down toward the bottom of the pot, there was some white fuzzy mold growing. These pots are in my car port and no direct sunlight reached them.

  1. Is the fungus/mold a problem? 2) Will this harm the plants?

I searched and found in another article here that mold is impossible to ignore. I just want to actually have a successful garden and harvest things. Please let me know if I need to clarify anything.

Thank you for your reading. Thank you in advance for any advice/feedback/tips. Anything is greatly appreciated.


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