Potting soil mix for marijuana

A question I get a lot is: What’s a good mixture for potting soil? Example: how should I mix perlite and vermiculite to get a good mixture?

What are other good soil mixtures?

I was thinking about trying Ideal 420 soil, they say that you can grow from start to finish just using water. I have seen a couple of grow journals that say it works. I saw 2 that said that it did not. The 2 that I saw that said that it did not work, one guy quit after 3 weeks the other did not even try it he just said it would not work.

Price right now is $49.00 with free shipping for 1.5 cu ft.
Looking at the cost of nutes and soil to grow in, and looking at just using 420 soil I am leaning toward 420 soil. They recommend using RO or distilled water so PH should not be a problem. Just check the PH of the water before you use it. It should already be neutral.

1 Like

To sterile dirt;
I add 20% perlite,
10% vermiculite,
20%peat moss.
3-4tbs. epsom salts
3-4 tbs. pulverized dolomitic lime.

When using commercial nutrients like Marijuana Booster; I prefer to have sterile soil without any N-P-K rating. This allows me to know exactly what I am giving to my plants


Epsom salts? I mean, I haven’t read of that for a mix, I will be mixing my own, peat moss 2.2cuft squares in plastic are available, perlite, and vermiculite, I may have to order dolomite or go to a dedicate garden store or local grange store for that. But Epsom salts, I dunno, that scares me, I suppose it does something I don’t quite understand. I am still tryng to decide if I need to eventually need five gallon buckets, or an almost as big plant pot each for my plants, as a first time grower.

1 Like

Magnesium Sulfate. MgSo4. It is one major part of nutrient blends.


Epsom salts is just magnesium sulfate, it provides magnesium and sulfur, very much needed by the plants for healthy photosynthesis and other cellular development. In its own way it is not much different than dolomite lime, just a good natural mineral salt. Not everything needs to come out of some animal’s butt to be healthy and natural for your plants, lol.


In fact; I meant to say this earlier. Dolomitic lime is a source of Calcium and magnesium, I believe.

1 Like

Yeah, so I could then add in Epsom salts in place of dolomite lime from what I am gathering. Maybe a good thing, cause locally I was able to purchase peat moss in bulk cubes, perlite, and verminulite, but they didn’t have any dolomite lime in the garden section.
I am in a hurry of course and should have ordered dolomite lime, but my seedlings, a couple of them are growing fast, like several need planted in intermediate sized 6" pots tomorrow, outgrowing the seedling starter container.

Oh, wait, I see that Epsom salts is used with dolomite lime as well in a mix with perlite, vermiculite, and peat moss.

One thing we did not mention. Dolomitic lime is also a ph buffer.

Used together, with Epsom salts, you get a pH, Cal-Mag buffer. :smiley:


Oh, I think I was missing something, “add to sterile dirt” all the mentioned ingredients. I mean, I bought dolomite, perlite, vermiculite, peat moss, and already have Epsom salts. We have a local grange supply store, they had plenty of 3.2 cu.ft. peat moss, very large bags of perlite. Not sure what to do about “sterile soil”. I probably don’t need sterile dirt, basically get away without adding any. I had better check the marijuana bible, and some sort of video I saw on youtube, especially concerning the rations of ingredients.
Maybe the original poster can forgive me for digging into his post with my trials and tribulations.

Sterile dirt is dirt you find in a walmart, garden store that shows on the bag, that it contains no fertilizer additives or anything that would not be good for produce. That is the key.

Sterile dirt contains no bugs etc etc

I used to get bags for 1.99 and that would fill a 3 gallon pot with the peat perlite vermiculite erc, etc. and possibly some small stones in the bottom for passive Oxygen uptake.Peapt moss is what it is. You get a lot for not much money. Buy a plastic tub or small trash can and save it back :slight_smile:

As far as Perlite; What do you mean large bags? How Much? I buy Commercial bags 400lbs. at a time. Maybe I can help you out.

1 Like

Okay, “sterile dirt” is indeed another way of saying peat moss, from what I am seeing, if that is true, I have lots of sealed peat moss I just bought, several 3.2cu.ft and one 2.2 cu.ft squares of Canadian peat moss. I am gonna check the “guides” on this sight, I just noticed them…Anyway, I need to mix me up some, or something, I got some seedlings in peat cubes that need to be transplanted to six inch pots. Right now I am under my allowed limit, one seed never germinated or broke open, another did and stopped right there, and one other started growing and won’t put out its first two leaves after the two round ones, so I had to start me some more seeds in peat pellets.

Sterile dirt is just that, it is not peat moss. Unless you get a special type of peat moss that might be fortified with added minerals, it will not contain many of the minerals that sterile dirt will have, such as silicon and other “rocky” minerals that naturally occur in dirt. Also obviously it will have a different consistency to peat moss and may have very different drainage and water retention properties than plain peat moss. Also peat moss by itself is notorious for becoming quite acidic as it starts to break down. You would certainly want some pH stabilizing minerals added.

Well, ya know, I thought a lot of folks were growing marijuana with soil less mixtures, that of peat moss and such, without any grit/sand—dirt? I was watching a video on youtube, and it was indepth, talking about one part peat moss, one part pearlite, one part vermiculite. Ha, yeah, when I was at a garden supply section of a local large store, they sold large bags of potting soil with cocoanut fibers mixed, I mean, maybe I should have just bought that, dunno at this moment.

Sterile dirt is “Dirt” Peat moss is not! “dirt”.

Unless you are experienced, and plan to live in and about your grow room; You do not want to grow in a simple peat moss mixture. I have experimented with that, and the medium can dry up extremely fast. Adding dirt allows you to screw up a little and not lose your plant

1 Like

Sterile dirt is “Dirt” Peat moss is not! “dirt”.

Unless you are experienced, and plan to live in and about your grow room; You do not want to grow in a simple peat moss mixture. I have experimented with that, and the medium can dry up extremely fast. Adding dirt allows you to screw up a little and not lose your plant

1 Like

Yeah, I agree, I mean, I have lots of experience growing houseplant and other plants, and very few times have I seen plants grown in a light medium, usually items touted as for hanging plants, like woman of the home once ordered strawberry plants that were hybrids, they arrived in just peat moss and perlite, maybe vermiculite and were in these little synthetic mesh hanging bags, and got dry too fast and it kept them sort of small. So, I need to get some “sterile dirt” to mix with my other ingredients, or get some emergency potting soil with such in a bag from the local store or Walmart, for my young seedling plants. I am sure this information can help others reading this, seems “soil” is almost a near murky area, probably why a person looks on the net and notices folks with real small plants that are supposedly mature.

Then there is that whole “wetting agent” thing, saw on the internet video that some folks add in a little dish soap with water and the fertilizer, but I need to re-review that, could have been for the video that talked of no sterile dirt at all.

1 Like

You dop not need a wetting agent unless you plan on using a foliar application.

Soil is not murky either. Any soil you get at a garden store, is for Joe Homeowner and his garden. He does not worry about fertil;izer, and if he gets a few flower, he feels successful.,

All you need to ask for is: PLain clean dirt. I used to buy it at the dollar store, or wally’s. Any good garden store should have bags of plain dirt. approx. 1.99 us

Can you take a few minutes of your tume to explain all that to me? I need to learn how to make my own mixes and how you go about doing along w stuff like how vermiculite and perlite/peat moss effect the plant and how much you should normally use in a mix. What i really wanna know is how do i mix my own soils i cant cause i dunno hpw everything works but ill be working for an indusrty one day so i gotta know the whats and whos

welcome to the forum.

Go back and read my directions, give it a shot, and you should do fine.

If you want an in depth explanation of the benefits of perlite, vermiculite and peat moss; I suggest you do a search and read the found info. All commercial growers use the same ingredients.

Happy growing