So I found this website with some recipes https://savvygardening.com/diy... and there's this one recipe I'm interested in crafting:

6 gallons sphagnum peat moss or coir fiber
4.5 gallons perlite
6 gallons compost
1/4 cup lime (if using peat moss)
1 & 1/2 cup of the DIY container fertilizer blend found below OR 1 & 1/2 cups of any granular, complete, organic fertilizer.

I would like to know. Do I absolutely have to use compost for this recipe? Or can I get by without using it? I live in an apartment and don't have access to a yard to make compost nor can I find any stores or garden centres here in Canada who have it readily available (if at all, I don't think stores sell it). I have granular nutrients I intend to top dress with for nutrition, and every other item in that list I can obtain besides the compost. Is compost an absolute necessity?

The term compost means two different things, in US vs Britain at least.
And purchased compost can be all over the place for content.

I'd save the hassle and uncertainty.. just buy quality pre-made potting mix. You won't save money by mixing.. you'll have odd amounts of leftovers, where you going to store that [or just throw away? ]
Don't overthink it. Ain't brain surgery growing a plant.

sallyg said: The term compost means two different things, in US vs Britain at least.
And purchased compost can be all over the place for content.

I'd save the hassle and uncertainty.. just buy quality pre-made potting mix. You won't save money by mixing.. you'll have odd amounts of leftovers, where you going to store that [or just throw away? ]
Don't overthink it. Ain't brain surgery growing a plant.

Well I'll just store what I don't use in my closet for next grow.

I'm using what I THOUGHT was quality premade potting mix, and tbh, I think it's stunting the growth of my plants. It's highly alkaline (8, a high 7) and I'd like to avoid the hassle of it all.

Here in Canada, the only readily available amendment for reducing my soil pH is aluminum sulfate, and I'd rather not put that into soil for crops I intend to ingest. I cannot obtain fast acting sulfur, iron of sulfate or any other form of soil acidifier very easily. We're very derelict when it comes to what items are allowed to be imported into this country, and thus what items are available for use. I can't even get PROMIX's good products, they're only sold at one place over 200 miles away, and shipping for that would be WELL over $100.

You might think it's easier to just purchase quality potting mix, and while that might be true for those who have the products readily available at their hardware stores, here in Canada, we do not. They offer us garbage products that are more less almost completely useless. Making my own potting mix is sort of a must. I hope you understand.

Wow, sorry, I had no idea.
I cannot advise on this situation specifically.
Hope in a day or two someone else can help here.

bobj59108 said:
I would like to know. Do I absolutely have to use compost for this recipe? Or can I get by without using it?

Maybe direct your questions to the creator of your chosen "soil recipe" - the rest of us gardeners can only guess.

My guess:
the compost is added to the mix to add the biological component- the many billions of bacteria/fungi that will be required to breakdown your 'organic fertilizer' components into the minerals your plants can then absorb.

Compost also adds some nutrients: coco coir / peat moss does not add any nutrition.

If you use soluble fertilizers, this biological action isn't required- as evidenced by fabulous plant growth in a well-managed soil-less hydroponic system.

Here is one of the best articles I've found on mixing your own soils, as it gives examples, recipes, and research study footnotes.

https://attra.ncat.org/htmlpub...

Good luck- I mix my own because I need lots! There is much more to learn... some of those lessons by trial and error

@ bobj59108

Quality potting soil is getting hard to find everywhere. Most of it is now made from ground up wood scraps from the local landfill. Sounds as if they put a lot of lime in yours.

How are you checking the pH of the potting soil? What equipment and technique are you using?

If the pH is the only problem with your potting soil, you can acidify your irrigation water with regular household vinegar. If I remember correctly, 1/4 teaspoon of vinegar would lower one gallon of my tap water from pH 8.5 to pH 6. Verify your results with a pH test kit.

Most municipal tap water is adjusted to pH 8 - pH 8.5 for safety purposes.

(I used the General Hydroponics test kits which had a bottle of reagent, an eyedropper, and a color chart. When evaluating, hold a white piece of paper behind the test vial for the most accurate results.)

Other strategies would be to find an acidifying fertilizer, such as one intended for blueberries. In my experience, cannabis just wants to grow, and it will, as long as you don't give it a very good reason not to.