SQWIB
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Joined: Tue Feb 16, 2016 9:21 am
Location: Zone 7A - Philadelphia, PA

Testing a new potting mix

Testing a new potting mix for my indoor garden. The Bio-char is being added for water retention and nutrient retention and to reduces soil acidity decreasing liming needs.
If this works out, next fall I will be adding my city compost from the recycle center.

Used this mix for the 1 gallon pots and one grow bag, marked w/red tape
  • 2 bucket (3 gallons) peat moss
  • 1 bucket (2 gallons) Perlite
  • 1 bucket (2 gallons) Black Kow composted cow manure
  • 1 bucket (2 gallons) Coffee grounds
  • 1 bucket (2 gallons) Bio-char
  • 1 cup pelleted time-release fertilizer (osmocote plus) (6 scoops)
  • 1/4 cup of Blood Meal
  • 1 cup lime (to counter the acid of peat and keep the pH level near neutral

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rainbowgardener
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Location: TN/GA 7b

I haven't done it lately, but I used to make an eco friendly potting soil for seed starting/ seedling growing:

A basic potting mix recipe goes like: compost or something organic that supplies texture and nutrients, something to keep it fluffy and moisture holding, something mineral or gritty to promote drainage, more or less thirds of each. In my quest for eco-friendly sustainable potting mix, the recipe I have come up with is mushroom compost (left over from growing mushrooms), coconut coir (outside fuzzy stuff from coconuts) instead of the peat moss that people often use, rice hulls (left over from milling rice) instead of perlite or vermiculite. All of this is agricultural by-products and all but the coconut coir can be fairly locally sourced. None of it is mined, heated to high temperatures or otherwise environmentally destructive to produce.

So I think it is very eco-friendly. It turns out that it is not as nitrogen rich and maybe generally not as nutrient rich as the Miracle Gro potting soil I used to use. So I need to supplement it a bit. Things I have used include soaked alfalfa pellets, aerated compost tea, seaweed fertilizer, etc. I still need to keep tweaking this part a bit.

SQWIB
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Joined: Tue Feb 16, 2016 9:21 am
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My new potting mix hasn't killed anything yet.
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PaulF
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Location: Brownville, Ne

I'm just too lazy to start mixing my own mix. For twenty years I have been using commercial potting mixes with success. No need to experiment now. So long as I go for the more expensive and better known mixes I have no problems. I have used cheap-o brands and they have too many rocks and dirt clods and do not perform as well.

Homemade mix would be fun to mess with, but like I said, I am just too lazy.

imafan26
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Location: Hawaii, zone 12a 587 ft elev.

I am reviving this thread to see if anyone has any other soil recipes. I want to try to add more organics to my potting soil recipe which is basically peatlite 50/50. It works well on everything, but expensive. I have been using MG potting mix in pots when I cannot find perlite. It works but is heavier and really needs more perlite. Lately the MG potting mix has changed. They are using more composted forest products and less peat moss and perlite which is affecting the results. Plants will grow, but the containers are staying wet longer so I have to be careful with watering. It is more of a problem for me to have a mix that is too wet than to have one be too dry. I keep the mix dry with more perlite or cinder because my mix has to survive the rainy season and humidity. Average rainfall has been declining it is about 52 inches in a normal year. Average daily amounts less than 0.10 inch, 60% of the rain falls in the rainy season from Nov-May. Jan monthly ave 3 inches of rain. July average 0.5 inches of rain.

We have a lot of coconuts here, but coir is not that easy to find, so I still use peat moss. It is expensive but still available. If I replace some of the peat moss or add more compost to the mix, it will decrease the cost but increase water holding capacity. It means I need to add more perlite or cinder to the pot. I have researched the internet and most recipes use:
4 parts peat moss
1 part perlite
1 part vermiculite
4 parts compost
1/4 cup lime
fertilizer (organic mix of rock dust, lime, bone meal, etc)

I know this mix would stay too wet for me in my humid climate. a 4:1 ratio of a wet ingredient that holds water to 1 for drainage would not tolerate a week of rain. I don't use vermiculite as it is because it holds more water than perlite and is even harder to get.

The wettest peat lite mix that I have been able to use is a 60/40 mix of peat to perlite. Basically 3 parts peat moss to 2 parts perlite. The pots do retain water but most pots that are not pot bound will dry out in 2 days if there is no heavy rain.

My question is if I can replace part of the peat moss with compost, what kind of compost should I get?
How much manure can I add to a potting mix and not have it kill everything? (Been there, done that)
I use synthetic slow release fertilizer in pots. It works well, so I do not intend on adding other kinds of organic fertilizers (bone meal, blood meal). I do use fish emulsion occasionally, but not routinely.

This is what I have:

Composted steer manure
Amend garden soil ( it is mostly a fertilizer not a compost)
Sta green flower and vegetable soil - never used it before, but the ingredient list looks good, it has peat moss as one of the listed ingredients.
En rich - mostly forest fines. I use it mostly in the main garden. I haven't used it in pots.
When I went to the garden center there wasn't any bagged compost. I don't use the local green waste because it has a very alkaline analysis pH 8.13, and my mom used it and has had weeds (nut sedge) and herbicide damage from it, so it is not good quality.
MG potting mix
Black gold is the best compost I have found, but I haven't seen it lately.

I just restarted my worm bin so I don't have any vermicast right now. I do add a couple of handfuls of vermicast to the potting mix when I do have it available. I do trench composting but I don't have the space for a compost pile and it would attract too much vermin.



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