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Specific Soil Mixes for Growing Cannabis

Specific Soil Mixes for Growing Cannabis

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An article about the special ladies in our lives, along with the tender youngsters. Special clones or plants that are long IBL/heirloom types fairly often require some soil tweaking. That’s what specific soil mixes for growing cannabis are all about today. We all don’t just crop out commercially available clones, and if you like to walk on the wilder side of cannabis growing, today’s article should enlighten you a bit. Let’s rock and/or roll baybee…

Sprouting Specific Custom Soil Mix

I have heard a lot of times over the years how certain commercial soil mixes are “too hot” for sprouting cannabis. What this means basically is the soil is too powerful, and the little plants can’t handle the big bang and pH changes associated with a lot of nutrients in a soil mix. Let me assure you right now, soil mixes commercially available like Ocean Forest, or Happy Frog by Fox Farm are primo for any germination of any cannabis. All G&B potting soil mixes are also primo. Most bagged organic soil mixes will work awesome for this purpose.

I Use 2 Part TLO Soil and 2s Part Ocean Forest and 1 Part Castings and 1 Part Perlite for Sprouting
I Use 2 Part TLO Soil and 2s Part Ocean Forest and 1 Part Castings and 1 Part Perlite for Sprouting

The problem here usually lies, in my experience (I have been growing steady for 45 years+), with either your water source or the fact that you feel compelled to feed your sprouting plants—you absolutely do not need to feed them. Good quality commercially available soil mixes are buffered well to keep pH in check. If your water source is either low PPM (0-39 PPM) or already lower than 7.0 pH, like some well water can be that is high in iron and sulfur, then you will cancel out that buffering to some degree. Your water needs to be, say, 40 to 65 PPM and it needs to pH at 7.0 or higher.

This Alkaline Water is pH 9.6 and it is 40 PPM
This Alkaline Water is pH 9.6 and it is 40 PPM

In the photo above you can see a nice water option. I got a case of these for about $9.00, and I keep them handy. If your pH is diving too low for your sprouts, you can blend in some of this water like 50/50 with your water, and it should fix things up within a week or ten days.

Custom Soil Mix for Sprouts
Happy Sprouts Grow Up to Be Happy Buds
Happy Sprouts Grow Up to Be Happy Buds and That’s a Fact Jack

Here’s a basic and easy custom soil mix for sprouts. Basically, you want high aeration, buffered pH, and diverse food for the soil life and the plants. Right out of the bag, something like Ocean Forest or any G&B brand potting soil will work fine, but to up your chances of success there are a few tweaks I would use myself, and here they are…

  • 2 parts quality bagged soil mix.
  • 1 part perlite or pumice.
  • 2 parts earthworm castings (bagged is fine), or high-quality. There is some compost out there in bags that is of decent quality.

That’s it! Like I said, you can use just the quality soil out of the bag, but if you overwater it, you will have some issues that my custom mix will avoid easily. Just don’t feed your sprouts anything (ANYTHING) for at least their first 10 or 15 days above ground. Use good groundwater with a PPM of at least 40 and up to 65 PPM is fine. Bottled spring water works fantastic for sprouts all by itself. If your sprouts do take a pH dive, use some of that alkaline water above and that should fix things fast.

Bare Rooted Clone Specific Soil Mix

Now, you do have to be a bit careful with this custom soil mix because these freshly (bare) rooted clones, like you, would have from an aero-cloner, are a tad sensitive out of the gate. You want their soil to be weak/mellow/buffered/aerated etc. I use either of those two brands of bagged soil I mentioned above for these specific custom soil mixes. Use small containers, like 3” wide and 4” tall (about), because the smaller, the better to some extent here. Never compact this mix at all. The mix should be moist but not wet.

Custom Soil Mix for Bare Rooted Clones

Here’s the standard mix I have used for a long-long time with great success…

  • 2 parts quality bagged soil.
  • 1 part vermiculite.
  • 2 parts quality castings or compost.
  • 1 part perlite or pumice.

Like I said my success rates are high, almost 100%. Over the course of a year, I might lose two clones at transplant. Usually not the fault of the soil, more human error—LoL. And you could even go simpler here if you wanted to…

  • 2 parts bagged soil.
  • 1 part vermiculite.

I like adding the castings or compost to add valuable organic matter to the mix that makes not only the microlife very happy, but the plants too! ?

Strain Specific Custom Soil Mix

Sometimes, like in the case of Deep Chunk, an Afghanistan strain that is a long IBL, certain genotypes have adapted over time to different environmental factors. In the case of Deep Chunk, she highly prefers higher soil pH ranges above 7.0. In fact, she can get very unhappy in “normal” lower pH ranges most plants do just fine growing in. Another cannabis line like sativas from the more jungle-like places of South East Asia, can’t even tolerate a soil pH above 6.8 without getting very pissed off looking, growing slowly with “bleaching” and curling. These problems, at the very least, hit your yields hard.

Custom Mix Additions for High pH Lovers
If You Like to Grow a Wide Variety of Legit Exotic Strains You Need to Know Your Soil Mixes
If You Like to Grow a Wide Variety of Legit Exotic Strains You Need to Know Your Soil Mixes
  • Crab Meal: You can add this right on the spot because it breaks down so slowly and has a lot of calcium (Ca) present to buffer the pH upwards a bit; this stuff is perfection. Add approximately 1 cup of this (or any shellfish meal) per 6 gallons (1 cubic foot) of soil. Moisten the soil and allow it to sit for about 24 to 48 hours before using.
  • Ground Oyster Shell: Another one you can add a day before using the soil. I would use about ½ cup per 6 gallons of soil for this purpose.
  • Bottled Water Additions: Using that alkaline water is a great move here and you can mix it into your plant water, or, bottled spring water works great. Any good groundwater with a pH of at least 7.0 and a PPM between 40-65 should be all good. You can bubble dolomite lime in your water before using. This is what I use on things like Deep Chunk. A higher PPM (around 60-65) added by bubbling dolomite lime will hold a strong pH value of just about 7.0 to 7.4, which is perfect for a Deep Chunk. This also adds valuable Ca and Mg that all cannabis plants love.
Custom Soil Mix Additions for Low pH Lovers

This one is actually how many gardens grow, in containers. With soil a bit on the acidic side, and if you have some issues, it is very likely that your pH has dived rather than risen. Like 95% likely in my experience. There’s really only one thing you need to do if, in fact, your pH has risen too high—but it likely hasn’t—or your heirloom cannabis plants need lower pH ranges to be happy…

  • Lower Water PPM: This is all you will need to do to gently lower the pH and make any low pH lover happy. If you normally run 60 to 65 PPM, let’s say, then just drop your pH value by 30%. Or in other words, to about 40 PPM. That’s the only and best move I know of to do it right.
  • Natural pH Lowering Additions: If you run exclusively heirloom jungle sativas, you can make additions to your standard soil mix to help along that direction. Cottonseed Meal, and Neem Seed Meal are both very good at lowering soil pH ranges. Adding about 1 cup of either of these per 6 gallons of soil does the trick. I have used this to make mini soil batches to accommodate heirloom jungle sativas. You must however let these additions decompose for 30 days in the soil before using it.


If you are using TLO soil, you can just use your used soil (see photo below) in place of bagged soil for sprouts, but NOT for bare root clones, TLO soil is a bit too much bang for them right off the bat.

When I say ‘bubbling’ I just mean bubbling water like you would a living tea. Remember that whenever you water your container soil, all that organic matter tends to lower pH while actively decomposing. So, if you do have a pH issue, it is that it is too low, way more likely, than too high. Check out my 2nd Edition TLO Book and learn more about soil recycling and all-natural methodology in containers.

You Can Use Your Used TLO Soil for Sprouts in Place of Bagged Soil But Never for Bare Root Clones
You Can Use Your Used TLO Soil for Sprouts in Place of Bagged Soil, But Never for Bare Root Clones

Never, EVER, use pH-Up or pH-Down on your living soil—it will go enormously bad within a couple of weeks of using it. Grab yourselves some cool ass genetics over at Kingdom Organic Seeds  to start a new growing adventure with! Speaking of KOS, my movie and a doobie recommendation for July is: Big Trouble in Little China, along with a nice doobie of Chunky Cherry Thai. Simply outstanding, and I have seen that movie a couple of times already, but not for about five years. Hilarious, especially with a killer Thai like that one.

Well, I’m off for now, and I’ll see ya all back here next week, same Skunk time, same Skunk channel. L8r G8rs…

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