What is a Good Soil Mix for Cannabis Seedlings?

[Amnesia]

I won't be starting any seedlings for a few months, so now is the time to plan. I believe the initial soil I've used may be to blame for my slow plant growth problem during the plant's early life. I suspect it is because the seedlings haven't been rooting well. So, I'm seeking suggestions for organic soil growing.

As Mary Poppins said, "Well begun is half done!"

 

[GoodShit97]

I won't be starting any seedlings for a few months, so now is the time to plan. I believe the initial soil I've used may be to blame for my slow plant growth problem during the plant's early life. I suspect it is because the seedlings haven't been rooting well. So, I'm seeking suggestions for organic soil growing.

As Mary Poppins said, "Well begun is half done!"

Im hooked on promix from start to finish. Its the easiest media ive worked with in 5 years.
Ive run FF ocean forest and happy frog seperate and mixed together, with added perlite.
Fox farm original mix
Mother earth groundswell
Roots organic 707
Coast of maine Stonington blend
Moisture control Miracle gro outside (terrible stuff)

Out of all of those, im hooked on promix. It has nothing in it but peat, perlite, and dolomite lime.

 

[moe.red]

I am doing my first soil grow.

This is working in solo cups so far


Then I will be moving to these at transplant

 

[Amnesia]

Im hooked on promix from start to finish. Its the easiest media ive worked with in 5 years.

I've thought about using the same, or maybe nearly the same, mix for seedlings. My standard mix is probably too hot for them. I have used FFHF and the seedlings didn't like that.

Out of all of those, im hooked on promix. It has nothing in it but peat, perlite, and dolomite lime.

I haven't tried Promix. I know many folks like it and I just recently found a hydro store that carries it. I understand it doesn't have much in the way of nutrients, and that's okay for seedlings, for a while. Unfortunately, I'm well stocked with FFOF. It's helpful to know you use the same basic soil, though.

 

[GoodShit97]

I've thought about using the same, or maybe nearly the same, mix for seedlings. My standard mix is probably too hot for them. I have used FFHF and the seedlings didn't like that.


I haven't tried Promix. I know many folks like it and I just recently found a hydro store that carries it. I understand it doesn't have much in the way of nutrients, and that's okay for seedlings, for a while. Unfortunately, I'm well stocked with FFOF. It's helpful to know you use the same basic soil, though.

Ffof is good soil imo, it just is a little hot for seedling, so something like the biobizz light mix or promix would probably be your best bet for seedlings.

I went organic so that was the reason behind promix. I was gonna go away from organics and go back to synthetics, but now that @Shaded is here to rewrite an article on gaia green, im gonna stick to it.

 

[steamroller]

I start my seedlings in COM seed starter. I use solo cups. When it is time to up pot I start with a more full soil. I have a history of mixing soils.
I have mixed FFOF, Pro Mix and next grow Sohum LS all with Coast of Maine Stonington. Next grow will be equal parts COM ST, Pro Mix, Sohum LS with added perlite.

 

[freezeland]

Jiffy organic seed starter mix. Cheap and available most everywhere.

 

[growsinse79]

I won't be starting any seedlings for a few months, so now is the time to plan. I believe the initial soil I've used may be to blame for my slow plant growth problem during the plant's early life. I suspect it is because the seedlings haven't been rooting well. So, I'm seeking suggestions for organic soil growing.

As Mary Poppins said, "Well begun is half done!"

Cocoloco is the best I found.

 

[MysticEpipedon]

I am doing my first soil grow.

This is working in solo cups so far
View attachment 5579

Then I will be moving to these at transplant

View attachment 5580
View attachment 5581

Lush is my favorite pre-mixed organic soil.

I've used Pro-Mix as a base organic mixes, with good success.

 

[brettdawg]

I am doing my first soil grow.

This is working in solo cups so far
View attachment 5579

Then I will be moving to these at transplant

View attachment 5580
View attachment 5581

I used the bio bizz light on young clonea and seelings workes fine

 

[Pipecarver]

I use Promix and its good for almost 3 weeks before I start a light feed. I've learned though with peat based medium to add far more perlite than recommended, I'm up to 40% now to help stop compacting of the soil. Peat based soils shrinks and hardens with continual wet dry cycles and by the time your pots are 3 months old the soil is a tight compacted mass hard to penetrate and water correctly....40% perlite prevents that but it makes transplanting awkward with the mass breaking apart easily

 

[Shaded]

ProMix with added perlite

Amendments & Triforce start after the first transplant or around week 2/3

 

[Pipecarver]

ProMix with added perlite

Amendments & Triforce start after the first transplant or around week 2/3

Yes, I've added worm castings, gypsom & azomite recently but after I move out of the solo cups..seedlings just get Promix.....clones can have the mix but seedlings just get water saturated Pm

 

[Amnesia]

I use Promix and its good for almost 3 weeks before I start a light feed.

ProMix with added perlite

It seems Promix is a top contender. I suspect compacted soil is one of the problems I've encountered.

Some authors of soil articles do not recommend using peat-based products because they claim peat is unsustainable. They acknowledge that it's organic, but it takes a long time to be created and thus supplies are being depleted.

 

[Amnesia]

Amendments & Triforce start after the first transplant or around week 2/3

Curiously, amendments have not been mentioned in any of the seedling soil articles I've reviewed so far. I've drafted a recipe and will post it soon. I did add amendments to it, and will be interested to know your thoughts about it. There aren't many DIY seedling soil articles for cannabis.

 

[Shaded]

It seems Promix is a top contender. I suspect compacted soil is one of the problems I've encountered.

Some authors of soil articles do not recommend using peat-based products because they claim peat is unsustainable. They acknowledge that it's organic, but it takes a long time to be created and thus supplies are being depleted.

there's similar thought processes to perlite as well. Try to re-use and recycle what you can is my only advice.

IMO with organics seedlings don't need nutrients until their cotyledons naturally fall off so around week 3 anyways. I believe most synthetic users will start at around 300ppm for seedlings?

 

[Amnesia]

IMO with organics seedlings don't need nutrients until their cotyledons naturally fall off so around week 3 anyways.

I'm only considering organic methods.

I've seen the advice about cotyledons frequently. It's probably a good indicator of when to start nutrients. One of my goals for seedling soil is to provide a medium that enables the plant to do what it wants to do--create roots. That, I believe, is how soil compaction matters.

 

[Amnesia]

Here are some of my thoughts based on reviews of seedling soil articles I found using Google searches:

Thanks to everyone for the helpful recommendations. I've tried a few commercially available seedling soils without much success. Commercial products are sure to compromise for broad appeal. They, therefore, do not optimize for our favorite plant. So, I ask: Could we do better by developing our own seedling mix?

Many authors claim that the seedling stage is a critical part of a plant's life. I believe them. Cannabis is resilient and can overcome many problems, but it doesn't make sense to rely on its capability to do so. I suggest it's better to give them the best beginning we can.

So, what is the best soil mix for cannabis seedlings?

I specifically searched for cannabis seedling soil mix recipes, and only found a few. Those that are for cannabis have several ingredients in common. Coco coir is the first ingredient in every recipe. As an alternative, many recommend sphagnum peat moss with lime. (Most authors view the two as interchangeable.) Perlite was also on every recipe. Most also included vermiculite. Compost was also commonly included. No recipe included nutrients or supplements.

There is little consistency regarding the ratios of ingredients. For example, some had coco coir at 80%, some had it at 40%, others had it at 25%. So, ratios are something to consider.

I'm thinking of a recipe something like this:

4 parts coco coir
4 parts compost
1 part perlite
1 part vermiculite

Plus, tiny amounts of the following supplements:
magnesium sulfate (Epsom Salts)
calcium sulfate (Gypsum)
trace minerals (Azomite)
root growth stimulant (Great White or Recharge)

 

[Amnesia]

Try to re-use and recycle what you can is my only advice.

We think alike. Thanks.

 

[budsofmadison]

i was gonna use these to start my seeds in

 

[Zen_seeker]

It seems Promix is a top contender. I suspect compacted soil is one of the problems I've encountered.

Some authors of soil articles do not recommend using peat-based products because they claim peat is unsustainable. They acknowledge that it's organic, but it takes a long time to be created and thus supplies are being depleted.

Sunshine Mix #4 is also similar to ProMix HP/BX. About the same as HP I think G$ said. It does have Si in addition to the rest.

I can’t find it locally but have a bale and a bit left. Grabbed 2 bales of ProMix HP on sale JIC.

 

[Pipecarver]

Here are some of my thoughts based on reviews of seedling soil articles I found using Google searches:

Thanks to everyone for the helpful recommendations. I've tried a few commercially available seedling soils without much success. Commercial products are sure to compromise for broad appeal. They, therefore, do not optimize for our favorite plant. So, I ask: Could we do better by developing our own seedling mix?

Many authors claim that the seedling stage is a critical part of a plant's life. I believe them. Cannabis is resilient and can overcome many problems, but it doesn't make sense to rely on its capability to do so. I suggest it's better to give them the best beginning we can.

So, what is the best soil mix for cannabis seedlings?

I specifically searched for cannabis seedling soil mix recipes, and only found a few. Those that are for cannabis have several ingredients in common. Coco coir is the first ingredient in every recipe. As an alternative, many recommend sphagnum peat moss with lime. (Most authors view the two as interchangeable.) Perlite was also on every recipe. Most also included vermiculite. Compost was also commonly included. No recipe included nutrients or supplements.

There is little consistency regarding the ratios of ingredients. For example, some had coco coir at 80%, some had it at 40%, others had it at 25%. So, ratios are something to consider.

I'm thinking of a recipe something like this:

4 parts coco coir
4 parts compost
1 part perlite
1 part vermiculite

Plus, tiny amounts of the following supplements:
magnesium sulfate (Epsom Salts)
calcium sulfate (Gypsum)
trace minerals (Azomite)
root growth stimulant (Great White or Recharge)

Okay what is your nutrient regime going to be? Are you going with a company line? or are you going home made organic?

All I know of Coco is it requires more frequent watering than Promix does and that its more of a headache for new user's.............. but those that know how to use it love it so there's that too.....I have these fears...lol

I like using a company line and follow their feed schedule, its pretty well idiot proof and you can tweak it as you learn it better. Their science guys have done the work so I don't have to.....I use GH products and have started increasing my mix with more of their additives over the past 2-3 years

 

[Pipecarver]

Sunshine Mix #4 is also similar to ProMix HP/BX. About the same as HP I think G$ said. It does have Si in addition to the rest.

I can’t find it locally but have a bale and a bit left. Grabbed 2 bales of ProMix HP on sale JIC.

Yes I'll use that if its available.....My favorite though is Greenworld VPW30, they have 30% perlite to start they also have a vpw420 for pot but its more expensive. Promix for me $39/ bale+ tax....VPW30 $29+ tax....I like vpw30...lol

 

[Amnesia]

Okay what is your nutrient regime going to be? Are you going with a company line? or are you going home made organic?

I am currently using Gaia Green in accord with @Shaded's method. So, I'm not considering homemade organic nutrition now, but also am not ruling it out for later. I am considering using my own compost, but I'm worried about it because I don't know what life might be in it. I've considered sterilizing it, but using a commercial product would be much easier.

I'm only talking about specialized soil for seedlings. That means the emphasis isn't on nutrients. Instead, the idea is to create a soil that promotes optimal root growth. Thus, for example, soil density would be significant to this project. The idea is to optimally prepare plants for their transition to the vegetation stage when nutrition matters most, when they're moved to larger pots.

I have seen many discussions about soil mix for the vegetation stage. I have seen none for the seedling stage, which is the stage that is currently causing me the most difficulty. So, that led me to start thinking about how the seedling stage could be done better. That led me to consider a specialized soil for cannabis seedlings.

All I know of Coco is it requires more frequent watering than Promix does and that its more of a headache for new user's.............. but those that know how to use it love it so there's that too.....I have these fears...lol

That is my understanding about coco coir, as well. So far, I found five different seedling soil mix recipes. Only one was for cannabis. All but one used coco coir as the main ingredient. The one that didn't use it, used compost instead. Most listed peat + lime as an alternative, but I ruled that out for this seedling mix because there are problems with peat, compaction being one of them.

Equal parts of coir and compost are used for this initial draft recipe. I am not sure that's best, however. Experimentation is probably the best test. Advice from those who are familiar with coco coir would be welcome.

I am a few months away from starting new cannabis plants, so there is plenty of time for me to think about a seedling soil mix.

 

[Rootsruler]

I'm going to add that maybe you should look at the seedling part in different stages. Most will start their seedlings in a small pot like a solo cup then up pot to a 1 gallon or maybe directly to their home. Because seeds are self contained in regards to nutrient I would imagine a fairly benign soil mix with almost minimal nutrient in it would be best and then up pot into a hotter mix once roots have been established in the solo.

I reuse my potting mix from the last grow as most of the nutrient has been used by the plant so very little remains. Haven't had a seedling yet that didn't thrive in it. I bottle feed so after up pot my strategy will differ from yours.

 

[Shaded]

I like to use the mix in my signature to start seedlings, and lately I've just been starting them without the EWC for the first few weeks. The trick with seedlings in soil is to mimic hydro as best as we can - high porosity, lots of oxygen via fabric or air pots, with fast draining soils that have quick dry-back cycles that promote high transpiration.

I recommend sticking with a peat-based medium if you are going with Gaia Green however it is entirely doable in coco as you can see from Mr. Canuck although he switched to living soil quite some time ago.

 

[Amnesia]

I'm going to add that maybe you should look at the seedling part in different stages. Most will start their seedlings in a small pot like a solo cup then up pot to a 1 gallon or maybe directly to their home.

That's how I do it. I go from a sprout in a paper towel, to a seedling in a cup, to early vegetation in a one-gallon pot, and finally to whatever size pot I decide to use to finish--usually either a five- or seven-gallon fabric pot.

The scope of this discussion is the solo cup phase — the seedling stage — whether use of a specialized soil for that stage has merit.

I define the seedling stage as the time between the plant being a sprout and early vegetation. I've seen this referred to as the establishment stage. During this stage, the plant develops its first pair of leaves and begins to grow roots. I suppose we could also think of it as the time beginning when the sprout is first put in soil and ending when it is transplanted or perhaps when adding nutrients begins.

Because seeds are self contained in regards to nutrient I would imagine a fairly benign soil mix with almost minimal nutrient in it would be best and then up pot into a hotter mix once roots have been established in the solo.

That's true, but what do we mean by nutrients? Do we specifically mean macronutrients? What about micronutrients? Additionally, there are other growth factors than nutrients. That's what I'm contemplating regarding a recipe for a plant's first soil.

What does "minimal nutrients" mean? It probably does not mean the absence of any nutrients. The first roots in soil must serve a purpose beyond physically anchoring the plant. We know the plant needs moisture in the soil. What else does it need? Would that include micronutrients? If so, which micronutrients and how much? We know a seedling's initial growth focus is the roots, therefore, an optimal first soil would contain substances that promote root growth.

A plant's first soil also needs to have a structure that enables optimal root growth.

I reuse my potting mix from the last grow as most of the nutrient has been used by the plant so very little remains. Haven't had a seedling yet that didn't thrive in it. I bottle feed so after up pot my strategy will differ from yours.

I also reuse soil. I add to it, though. Lately, I've mixed it with FFOF in a 1:1 ratio. Then I add other amendments, such as rice hulls or earthworm castings. I began using synthetic nutrients and have gradually been converting to organic growing. It takes a while to learn as well as acquire the various amendments. I finally found a good hydro store, and that has been helpful.

Apparently, it's frequent practice to use a first soil that is the same as or similar to the soil used during the later stages of plant development. Basically, I'm wondering if we can improve on that practice. I have a notion that the beginning growth stage has a significant impact on all the stages that follow.

 

[Pipecarver]

That's how I do it. I go from a sprout in a paper towel, to a seedling in a cup, to early vegetation in a one-gallon pot, and finally to whatever size pot I decide to use to finish--usually either a five- or seven-gallon fabric pot.

The scope of this discussion is the solo cup phase — the seedling stage — whether use of a specialized soil for that stage has merit.

I define the seedling stage as the time between the plant being a sprout and early vegetation. I've seen this referred to as the establishment stage. During this stage, the plant develops its first pair of leaves and begins to grow roots. I suppose we could also think of it as the time beginning when the sprout is first put in soil and ending when it is transplanted or perhaps when adding nutrients begins.


That's true, but what do we mean by nutrients? Do we specifically mean macronutrients? What about micronutrients? Additionally, there are other growth factors than nutrients. That's what I'm contemplating regarding a recipe for a plant's first soil.

What does "minimal nutrients" mean? It probably does not mean the absence of any nutrients. The first roots in soil must serve a purpose beyond physically anchoring the plant. We know the plant needs moisture in the soil. What else does it need? Would that include micronutrients? If so, which micronutrients and how much? We know a seedling's initial growth focus is the roots, therefore, an optimal first soil would contain substances that promote root growth.

A plant's first soil also needs to have a structure that enables optimal root growth.


I also reuse soil. I add to it, though. Lately, I've mixed it with FFOF in a 1:1 ratio. Then I add other amendments, such as rice hulls or earthworm castings. I began using synthetic nutrients and have gradually been converting to organic growing. It takes a while to learn as well as acquire the various amendments. I finally found a good hydro store, and that has been helpful.

Apparently, it's frequent practice to use a first soil that is the same as or similar to the soil used during the later stages of plant development. Basically, I'm wondering if we can improve on that practice. I have a notion that the beginning growth stage has a significant impact on all the stages that follow.

Hey, I think your making it more complicated than need be. I haven't had many seeds fail to pop or grow once they pop.

I use the spring water they soak in to saturate then squeeze out a small piece of folded paper towel. same on top....no standing water...in a sealed small plastic 2 oz cup for each strain or seed. In a warm location 2 days later there are tails......

I saturate a solo cup full of promix......no additives.......once the cup is saturated it will be 1/2 full of wet soil....poke a hole, drop in the seedling, tap in place, head above or at soil level, put in warm location off the bright lights.....plant grows...once it has leaves it can get moved closer and closer to the light until its developed enough to handle it all.......I'm 100% if it pops it grows....just straight Promix HP, BX, Sunshine mix, Greenworld Vpw30, .

They're good for almost 3 weeks with just water before they need a light feed to start.

 

[Amnesia]

I like to use the mix in my signature to start seedlings, and lately I've just been starting them without the EWC for the first few weeks.

Thanks.

The trick with seedlings in soil is to mimic hydro as best as we can - high porosity, lots of oxygen via fabric or air pots, with fast draining soils that have quick dry-back cycles that promote high transpiration.

I'm sure this is the direction I'm headed, and you've provided me with a solid foundation for further thought. So far, I've mostly been thinking about rooting capability. I haven't mentioned transpiration yet, and that factors into what is in this theoretical first soil.

We see solo cups commonly recommended, which, with their plastic sides, is contrary to your recommendation for fabric or air pots. I agree that oxygenation would be an important consideration for a first soil. Perhaps perforations on the sides of a solo cup would be helpful.

I recommend sticking with a peat-based medium if you are going with Gaia Green however it is entirely doable in coco as you can see from Mr. Canuck although he switched to living soil quite some time ago.

I understand. I question the practice of using a low pH substance (peat) and then adding a high pH substance (lime) to adjust the pH. What benefits does peat provide that warrants the addition of lime?

 

[Pipecarver]

Thanks.


I'm sure this is the direction I'm headed, and you've provided me with a solid foundation for further thought. So far, I've mostly been thinking about rooting capability. I haven't mentioned transpiration yet, and that factors into what is in this theoretical first soil.

We see solo cups commonly recommended, which, with their plastic sides, is contrary to your recommendation for fabric or air pots. I agree that oxygenation would be an important consideration for a first soil. Perhaps perforations on the sides of a solo cup would be helpful.


I understand. I question the practice of using a low pH substance (peat) and then adding a high pH substance (lime) to adjust the pH. What benefits does peat provide that warrants the addition of lime?

Perhaps perforations on the sides of a solo cup would be helpful.

Its a given that the cups have aeration but they're only in there 2-3 weeks depending on the size of the solo cups and it makes them easy to transplant out of and monitor watering needs