Organic component's in soil mixes

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MikeInOz
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Re: Organic component's in soil mixes

Post by MikeInOz »

jerrytheplater wrote: Sat Sep 28, 2024 5:31 pm
MikeInOz wrote: Sat May 25, 2024 6:08 am New Zealand is where Orchiata bark comes from. They have a seedling grade (called ''Precision'') which is 3-6 mm. You can use that or you can use a potting mix which conforms to the Australian Standard - I'm sure they import it to NZ - and use a sieve to separate the various sizes, or you can use one manufactured there and recommended by the nursery industry. Or you can use cow manure which has been thoroughly decomposed (at least one year) then dried and screened. Or you can use a good quality commercial compost which is again dried and screened. Or you can use leaf mould gathered from under Nothofagus trees or deciduous trees and once again dried and screened. Composts, cow manure and leaf mould need to be wetted and solarized in a plastic bag in the sun on a hot day to bring them up to at least 60 degrees C for a couple of hours. This removes all pests and pathogens. A few weed seeds may survive. It should be mature, clean and free of sticks and other undecomposed material. pH should always be checked before use and adjusted to about 6.5 if needed.
Hi Mike. Just wondering here. I can pick up steer pies in a field nearby that are very fresh. What is the next step? Collect in a bucket and place in a pile outdoors for a year exposed to the weather? Or should I collect and mix up with hay/straw and let it compost for a year outdoors? The landowner keeps his cattle outdoors all year. No barn where manure could be collected. Or maybe he does have a shelter or two I am not aware of.

I can buy bags of composted cow manure in the big box stores, but they are usually wet and very heavy in texture. Not sure what they would be like if I dried them out. Don't think I am going to do that indoors in my wife's oven. Soil/compost she'll tolerate. Manure? don't even want to ask.
Hi Jerry
I put the manure into a very large pot without drainage holes. It's about 3 feet high and wide. I wait until the manure is just moist so it can be broken up into small pieces and then add a little more water and cover the pot with another one and place it in a garden shed. After about a 6 months - more or less - it is in a crumbly texture (as long as it doesn't dry out) which I can then force through a plastic sieve with 1/4 inch holes. Then it goes back into the bucket for a few more months. By then it has become quite fine and I dry it out and then store it in bags. You want it to by fairly fine and consistent before use.
Another option is to dry it out and throw it through a garden shredder then wet it and store it. The more you turn it over the quicker the results. I would not add any straw. The good thing about cow manure is that it's fine textured because it's chewed twice. If you leave it in the rain you will lose quite a bit of it's nutrient content but it will still be a good addition to your mixes. Manure from grass fed cows is better than grain fed IMO.
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Re: Organic component's in soil mixes

Post by jerrytheplater »

Thanks Mike.
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SpriteFish
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Re: Organic component's in soil mixes

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I'm just about ready to redo my potting mix recipe using all if this information, and while trying to finalize the details I had a question.

I've decided to use a commercial potting mix as a base, and then ammend it with grit, and was wondering if there would beneficial to add bark aswell? If it won't change much then I'll leave it, but if you all think it would be worth it then I will. (It might only be beneficial for cacti that have adapted to growing on trees.)

In the future when I finally get around to adding a compost pile, I'll also probably add some of that. I did see someone say that they were apprehensive about adding things like manure and compost high in nitrogen due to concerns with unhealthy growth, I'm curious if this concern has any legitimacy? Prepaphs it just means I need to fertilize less frequently with stuff like that in my potting mix.
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Steve Johnson
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Re: Organic component's in soil mixes

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SpriteFish wrote: Fri Oct 04, 2024 8:02 amI've decided to use a commercial potting mix as a base, and then amend it with grit, and was wondering if there would beneficial to add bark as well?
Just wanted to remind you about something I discussed a few time in the past -- all types of tree bark become hydrophobic over time, doesn't matter if the bark is chipped, shredded or composted. The commercial wetting agent Mike gets in Australia isn't available in New Zealand, and I wouldn't trust any of the organic-based wetting agents you find. Stick with just the potting mix and grit.
SpriteFish wrote: Fri Oct 04, 2024 8:02 amI did see someone say that they were apprehensive about adding things like manure and compost high in nitrogen due to concerns with unhealthy growth, I'm curious if this concern has any legitimacy?
Yes it does -- add compost and/or manure to the mix, and it's too easy to overfeed unless growers really know what they're doing. Mike's levels of horticultural knowledge and growing skill are way beyond what the vast majority of hobbyists have, so it's best if we feed our cacti and succulents with the right fertilizer (plus any supplements if required) on a regular basis. Leave the compost and manure for crops and other leafy nonxeric plants.

By the way -- I still need to give you the stock solution recipes to supplement your Succulent Focus. Sorry about taking so long there -- I'll start running some numbers, and I hope to give you the recipes by Sunday.
If you just want photos without all the blather, please visit my Flickr gallery.
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Re: Organic component's in soil mixes

Post by SpriteFish »

Just wanted to remind you about something I discussed a few time in the past -- all types of tree bark become hydrophobic over time, doesn't matter if the bark is chipped, shredded or composted. The commercial wetting agent Mike gets in Australia isn't available in New Zealand, and I wouldn't trust any of the organic-based wetting agents you find. Stick with just the potting mix and grit.
I may have interpreted what Mike said incorrectly, but I beleive he said the wetting agent "saturaid" is a good option, and if this is the case then I'll be able to use bark. Of course if I interpreted this wrong, then bark won't be an option so that would awnser my question.
MikeInOz wrote: Thu Jun 13, 2024 12:34 am
Steve Johnson wrote: Wed Jun 12, 2024 2:37 am
MikeInOz wrote: Wed Jun 12, 2024 1:36 amWetta soil is actually a good quality wetting agent. The coir is (was) only used as a carrier. The Debco company (which is just down the road from me) has been bought out by a German company and I don't think they even produce Wetta soil anymore. I get my bulk potting mix from them each year. The quality varies every year. The water storing crystals are completely unsuitable for cacti as they need constant available water to work. Not many people use them for anything anymore. I still have a sackful from 30 years ago.
Hi Mike,

Thanks for warning us about the water-storing crystals. Wettasoil is still being sold by Bunnings under the product name Amgrow Wettasoil Professional:

https://www.bunnings.com.au/amgrow-1l-w ... t_p3010119

These are the ingredients from the product's Material Safety Data Sheet:

Wettasoil.jpg

Would you use the current product? If so, SpriteFish may want to contact Bunnings Australia and find out if Wettasoil can be shipped to New Zealand:

National Support Centre
Botanicca 3 – Level 2 East Tower, 570 Swan Street, Burnley VIC 3121 | Locked Bag 3004, Hawthorn VIC 3122
(03) 8831 9777
Yes Wetta soil was a Western Australian company and was probably bought out by Amgrow. It is what I use. It's also the same product they used in Saturaid.
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Steve Johnson
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Re: Organic component's in soil mixes

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SpriteFish wrote: Fri Oct 04, 2024 11:15 pm
Just wanted to remind you about something I discussed a few time in the past -- all types of tree bark become hydrophobic over time, doesn't matter if the bark is chipped, shredded or composted. The commercial wetting agent Mike gets in Australia isn't available in New Zealand, and I wouldn't trust any of the organic-based wetting agents you find. Stick with just the potting mix and grit.
I may have interpreted what Mike said incorrectly, but I believe he said the wetting agent "saturaid" is a good option, and if this is the case then I'll be able to use bark. Of course if I interpreted this wrong, then bark won't be an option so that would answer my question.
Saturaid might've been a good option at one time, but not now:

Saturaid.jpg
Saturaid.jpg (20.33 KiB) Viewed 737 times
The organic additives are a deal-breaker, as Mike stated that organics in wetting agents make them ineffective for cacti and succulents. We'll compare this with the Amgrow Wettasoil still available in Australia:

Wettasoil.jpg
Wettasoil.jpg (27.69 KiB) Viewed 737 times
Actually, the Saturaid in Australia might be okay because it's available as a liquid. But no such luck in New Zealand -- you can only get it in granular form (in other words, water-storing crystals).
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Re: Organic component's in soil mixes

Post by SpriteFish »

Steve Johnson wrote: Sat Oct 05, 2024 1:44 am
SpriteFish wrote: Fri Oct 04, 2024 11:15 pm
Just wanted to remind you about something I discussed a few time in the past -- all types of tree bark become hydrophobic over time, doesn't matter if the bark is chipped, shredded or composted. The commercial wetting agent Mike gets in Australia isn't available in New Zealand, and I wouldn't trust any of the organic-based wetting agents you find. Stick with just the potting mix and grit.
I may have interpreted what Mike said incorrectly, but I believe he said the wetting agent "saturaid" is a good option, and if this is the case then I'll be able to use bark. Of course if I interpreted this wrong, then bark won't be an option so that would answer my question.
Saturaid might've been a good option at one time, but not now:


Saturaid.jpg

The organic additives are a deal-breaker, as Mike stated that organics in wetting agents make them ineffective for cacti and succulents. We'll compare this with the Amgrow Wettasoil still available in Australia:


Wettasoil.jpg

Actually, the Saturaid in Australia might be okay because it's available as a liquid. But no such luck in New Zealand -- you can only get it in granular form (in other words, water-storing crystals).
Ah alright, well that awnsers the bark question!
I have just found another problem with my plan, the contents of the commercial potting mixes. We've discussed this before in regards to fertilizer, but ive just realized that the potting mixes that don't include slow release fertilizers (aka the organic ones), include manure instead. It's worth asking if you think I'll need to fertilize differently, or due to the small amount of manure plus amending the soil with grit that it won't make much differnce.

Also NZ potting mixes are based on bark, so I'm thinking the commercial potting mix will also be suseptible to hydrophobia. If you feel that one of these facts are an absolute deal breaker, my only organic options will be:
. Bark (hydrophobia concern)
. Peat (Enviromental concerns, highly absorbent so use very little, I beleive hydrophobia is a concern?)
. Tree Fern fibre https://www.bioleaf.co.nz/product-page/ ... fern-fibre
. Coco coir (I'm aware of all the cons, but it's worth listed as a final option)
. Spagnhum moss (I don't actually know much about spag moss, all I know is its highly absorbent, meaning id use very little)
. Worm casting (would this have the same concern as compost and manure?)
. Loam (Compacts and absorbent, I would only add a little.)
. Leaf mold (Honestly not even sure if this is available here, I'll have to check.)
By the way -- I still need to give you the stock solution recipes to supplement your Succulent Focus. Sorry about taking so long there -- I'll start running some numbers, and I hope to give you the recipes by Sunday.
For whatever reason I completely missed this the first time I read it! No worries about delay, stuff takes time and it's not urgent anyways. No rush whatsoever. :)
Last edited by SpriteFish on Sat Oct 05, 2024 3:05 am, edited 1 time in total.
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Re: Organic component's in soil mixes

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I wouldn't use coir unless I absolutely had nothing else to use. And probably still wouldn't. It has many problems. 1, It is often high in chloride, this can be mitigated by rinsing several times. 2, It has very low S and Ca and very high K. So much so that it can cause Mg deficiencies unless it is amended. Soaking in CaSo4 or MgSo4 and CaNo3 after rinsing can help. 3, Orchid growers were initially told that Coconut was the medium to end the use of all other mediums and went ahead and used it at full throttle. What did they find? Most had great results for a start and then found all kinds of deficiencies showing up later, severe chlorosis, death of roots and death of the entire plant in many cases. 3, Fungal mycelium LOVES coir unless it is completely consumed by composting. It thrives in it and if it gets a foot hold, the entire root ball can become choked with white mold and dead roots. Fungus tends to proliferate in dry, acidic conditions rather than moist alkaline ones where bacteria usually dominates. 4, It should have Fe and Cu added to it. 5, It is sometimes prepared from green husks and can contain unwanted plant hormones. Having said all that some people say they have used it with success but I think we should be aware of it's possible problems. It is interesting to note that some commercial Dutch nurseries said they never want to have to see or deal with coir products again.
Also in regards to coir, would the nutrient deficiency issues be irrelevant if I have a complete fertilizer that includes everything?
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Re: Organic component's in soil mixes

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SpriteFish wrote: Sat Oct 05, 2024 2:19 am
Steve Johnson wrote: Sat Oct 05, 2024 1:44 am
SpriteFish wrote: Fri Oct 04, 2024 11:15 pm

I may have interpreted what Mike said incorrectly, but I believe he said the wetting agent "saturaid" is a good option, and if this is the case then I'll be able to use bark. Of course if I interpreted this wrong, then bark won't be an option so that would answer my question.
Saturaid might've been a good option at one time, but not now:


Saturaid.jpg

The organic additives are a deal-breaker, as Mike stated that organics in wetting agents make them ineffective for cacti and succulents. We'll compare this with the Amgrow Wettasoil still available in Australia:


Wettasoil.jpg

Actually, the Saturaid in Australia might be okay because it's available as a liquid. But no such luck in New Zealand -- you can only get it in granular form (in other words, water-storing crystals).
Ah alright, well that answers the bark question!
That's a shame, really -- when I put my "Are you growing your cacti in a soilless mix?" presentation together, I had high hopes for chipped/shredded tree bark as the only organic component we'd need in a soilless mix.

Before we continue, I'll mention that pure loam is a mineral soil in the truest sense of the word. Pure loams don't exist in the real world because there is always a certain amount of organic material mixed in -- plant roots, decomposing leaves, etc. Loam-based commercial potting soils used to be common, although those days are long gone. The last time I saw one was a "custom" cactus mix I got at the California Cactus center back in 2011:

CCC_soil_sample.JPG
CCC_soil_sample.JPG (123.25 KiB) Viewed 711 times
Yep, that's sandy loam, pieces of tree bark, and pumice. When I used it for growing my Tephros and Eriosyce senilis in the 50/50 pumice and soil mix, I picked out the biggest chunks of bark and pumice first. I still have just enough of the CCC soil to repot them again, plenty of pumice in the 2 mm-5mm grain size range which I can buy all over the place. If you can find a commercial potting soil that's loam-based with a minimal amount of organic material (like what you see in the photo), the tricky part will be to find one that doesn't have nutrients pre-loaded by the manufacturer.
SpriteFish wrote: Sat Oct 05, 2024 2:19 amI have just found another problem with my plan, the contents of the commercial potting mixes. We've discussed this before in regards to fertilizer, but I've just realized that the potting mixes that don't include slow release fertilizers (aka the organic ones), include manure instead. It's worth asking if you think I'll need to fertilize differently, or due to the small amount of manure plus amending the soil with grit that it won't make much difference.:)
Cacti and succulents are ev0lutionarily adapted to living well on low levels of nutrients, so IMO it's best to feed them under your control rather than the control of a manufacturer pre-loading the potting mix with slow-release fertilizer or manure. Aside from the possibility of overfeeding, there's also the risk that your plants may not get some of the nutrients (including micronutrients) that are essential for healthy, vigorous growth.

If you can't find a loam-based potting mix that isn't already loaded up with nutrients, this brings us right back to square 1. We already know why bark is a problem, and Mike's numerous objections to coir should tell you that you can't use it. When I went through your list of organic options, Fernwood tree fern fibre really intrigued me. In fact, this may be the one and only organic component you'll need for a soilless mix. The correct proportion of tree fern to mineral grit is something we'll have to figure out based on the type of mineral you'll use for the mix. According to Fernwood, "Tree fern fibre is very durable and takes years to break down. I have read reports of orchids repotted after 15 years, and the fibre had not broken down." If that's correct and it's a good application for growing cacti and succulents in a soilless mix, the only reason for repotting is when your plants get too big for the pot and they need a bigger pot. That's a nice problem to have!
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Re: Organic component's in soil mixes

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Loam (Compacts and absorbent, I would only add a little.)
If you add soil, I would suggest perhaps not much more than 10-15% and watch the results.
I beleive with loam, they stopped using it due to compaction causing suffocation and other issues. I'm unsure if adding grit will stop compaction enough for loam to be suitable, I do know that Mike suggestedonly adding a little loam, so that's probably why.

In fact, I wonder if the reason many of your plants didn't do well in loam, is due to the same reasons it isn't used in container gardening! It seems obvious when writing it out, but it would phrase the issue you were having as the fault of container gardening with a high amount of loam, and not loam itself.

As I theorized in a differnt topic (I don't remember where), coarse sand may make a great substitute texture wise. I beleive with coarse sand I also have to use a small percentage due to suffocation concerns (like 20% or less?), although that may be wrong.
When I went through your list of organic options, Fernwood tree fern fibre really intrigued me. In fact, this may be the one and only organic component you'll need for a soilless mix. The correct proportion of tree fern to mineral grit is something we'll have to figure out based on the type of mineral you'll use for the mix. According to Fernwood, "Tree fern fibre is very durable and takes years to break down. I have read reports of orchids repotted after 15 years, and the fibre had not broken down." If that's correct and it's a good application for growing cacti and succulents in a soilless mix, the only reason for repotting is when your plants get too big for the pot and they need a bigger pot. That's a nice problem to have!


When I saw Fern fibre, I thought it looked like a great substitute for coir. If we're lucky it won't have as many downsides as coir, and might make a great addition, though I'm not sure how I'd test to see if it does has the same downsides.

I beleive it's recomended for plants that like moist environments though, so if I do use it I'll use very little and see if it drys out appropriately. This link has some more info: https://www.lovethatleaf.co.nz/collecti ... re-5-litre
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Re: Organic component's in soil mixes

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SpriteFish wrote: Sat Oct 05, 2024 7:44 am
Loam (Compacts and absorbent, I would only add a little.)
If you add soil, I would suggest perhaps not much more than 10-15% and watch the results.
I believe with loam, they stopped using it due to compaction causing suffocation and other issues. I'm unsure if adding grit will stop compaction enough for loam to be suitable, I do know that Mike suggested only adding a little loam, so that's probably why.

In fact, I wonder if the reason many of your plants didn't do well in loam, is due to the same reasons it isn't used in container gardening! It seems obvious when writing it out, but it would phrase the issue you were having as the fault of container gardening with a high amount of loam, and not loam itself.
Correct. When I purchased the first major round of cacti that started my current collection in June 2011, the people at the California Cactus Center who also sold me their "custom" soil-heavy cactus mix recommended adding pumice -- but only for some species. Unfortunately it was bad advice which set me up with a couple of problems I didn't realize at the time:
  • I have always watered my cacti from the top. Every time I watered them in 2011, I had to wait for the water to soak in, then do it again (and again) until I saw it coming out of the drain hole. Think it took 1 or 2 minutes (maybe longer in the bigger pots). That means poor drainage, and it was a red flag I failed to see.
  • Even though compaction wasn't an issue at that point (or maybe it was right from the get-go), all the loam in the mix was slowly suffocating the roots.
When I unpotted my cacti for the move from the CCC mix to soilless pumice and granite gravel in spring 2012, I was shocked by how bad the roots were. In fact, a few of the plants lost their roots completely. With the soilless mix, water drains all the way through in a matter of seconds (instantly with my smallest pots) -- excellent drainage and wide-open aeration that make cactus roots thrive.

As I've said a number of times in the past, my Tephros were the only cacti that wouldn't grow in the pumice and granite gravel because their very thin scraggly roots wouldn't grow in a mix that's too open for them. They love growing in the 50% pumice-50% CCC soil mix, so I'll disagree with Mike's advice on adding just a little bit of loam. When I water the Tephros, water drains all the way through in about 20-30 seconds, and compaction has never been an issue for me. However, I believe the 50/50 mix may be suitable only for Opuntioids (Opuntia, Puna, Tephrocactus, etc.). For any other cactus species we're growing, I'd say that Mike's advice for adding 15% loam to the mix is spot-on.
SpriteFish wrote: Sat Oct 05, 2024 7:44 amWhen I saw Fern fibre, I thought it looked like a great substitute for coir. If we're lucky it won't have as many downsides as coir, and might make a great addition, though I'm not sure how I'd test to see if it does has the same downsides.
You'll have to do what the rest of us have done -- trial and error. If you add fern fibre to the mix, see how your plants behave over the course of a year or two. If they respond by growing well, you're set. If they don't, you'll have to try again with another mix. Quite frankly, I'd be surprised if fern fibre has any downsides unless you have too much of it in the mix. Which brings us to this...
SpriteFish wrote: Sat Oct 05, 2024 7:44 amAs I theorized in a different topic (I don't remember where), coarse sand may make a great substitute texture wise. I believe with coarse sand I also have to use a small percentage due to suffocation concerns (like 20% or less?), although that may be wrong...

I believe it's recommended for plants that like moist environments though, so if I do use it I'll use very little and see if it dries out appropriately.
Yes, coarse sand is a good soil substitute -- 1 mm-2 mm grain sizes won't get compacted as loam will. Only problem is that coarse sand won't retain water, so I'll recommend a mix of 50% pumice (it holds more water than you might imagine), 35% coarse sand, and 15% tree fern fibre for some additional water retention. When your cacti and succulents are in their growing seasons, water released to the roots will dry out the mix.

How often you should water isn't something you have to leave up to chance, so rather than just guess, here's a scientific approach you can take...

Pot up a few of your cacti and succulents representing the various pot sizes you have in your collection. Make sure the mix is completely dry when you start the test. Using a digital scale, weigh them in their pots and write down the dry weight. Saturate the mix until water is coming out of the drain hole. When the pots stop dripping, write down the wet weight and the date when you started the test. Weigh them on a daily basis until they go back to their dry weight and write down the date. That ends the test, at which point you can figure out a good watering schedule. For example -- if the pots go from wet to dry in 7-10 days, water every 2 weeks. Cacti and succulents take an incredibly long time to die of dehydration, but killing them with kindness by watering too often is a common mistake inexperienced growers make. To avoid making it, here's a good watering rule I learned from a senior member back in 2012 -- when in doubt, don't.

I'll leave you with one final thought for the moment...
MikeInOz wrote: Mon Aug 05, 2024 2:42 am...plants are adaptable things and can keep going even with sub-optimal conditions.
To which I say -- why make do with sub-optimal when we know how to grow our cacti and succulents under more optimal conditions? In my carefully-considered opinion, potting mixes coming with nutrients pre-loaded by the manufacturer lead to sub-optimal results. That's why I'd rather take the time to give you the ingredients for a comprehensive and properly balanced feed you'll give to your plants with the mix I have in mind for you.
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Re: Organic component's in soil mixes

Post by MikeInOz »

SpriteFish wrote: Fri Oct 04, 2024 8:02 am

In the future when I finally get around to adding a compost pile, I'll also probably add some of that. I did see someone say that they were apprehensive about adding things like manure and compost high in nitrogen due to concerns with unhealthy growth, I'm curious if this concern has any legitimacy? Prepaphs it just means I need to fertilize less frequently with stuff like that in my potting mix.
Properly prepared cow manure has low to very low levels of N so don't worry about that aspect of it. Other composts - impossible to be sure. It all depends on what is in it, how it has been treated, how old it is and if it has been leached.
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Re: Organic component's in soil mixes

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MikeInOz wrote: Sun Oct 06, 2024 3:44 am
SpriteFish wrote: Fri Oct 04, 2024 8:02 am

In the future when I finally get around to adding a compost pile, I'll also probably add some of that. I did see someone say that they were apprehensive about adding things like manure and compost high in nitrogen due to concerns with unhealthy growth, I'm curious if this concern has any legitimacy? Prepaphs it just means I need to fertilize less frequently with stuff like that in my potting mix.
Properly prepared cow manure has low to very low levels of N so don't worry about that aspect of it. Other composts - impossible to be sure. It all depends on what is in it, how it has been treated, how old it is and if it has been leached.
I beleive with loam, they stopped using it due to compaction causing suffocation and other issues. I'm unsure if adding grit will stop compaction enough for loam to be suitable, I do know that Mike suggestedonly adding a little loam, so that's probably why.
If you are having problems with loam, it is because you are using a loam with poor or fragile structure. The best loams have stable ''crumbs'' which
do not interfere with drainage and hold their structure for the life of the mix. Akadama is an excellent example of this type of soil. However if you look for it you can find it in most areas. It is the clay content which is the most important factor if crumb formation, so a sandy loam will not have this structure, nor will a silty loam. Top soil is too high in organic matter. The best structured soils are usually found at sub-soil level such as under pasture and other natural areas which have not been disturbed by agriculture or, for example, where they might grow cherry trees and such. Such soils are often red but can also be black. Or.... you can just buy a bag of akadama - or not use any soil... In my experience cacti of all kinds seem to like akadama and many roots attach to the particles.
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Re: Organic component's in soil mixes

Post by SpriteFish »

This was the potting mix I was planning on getting just you all can see it: https://tuigarden.co.nz/product/tui-per ... ising-mix/
If you are having problems with loam, it is because you are using a loam with poor or fragile structure. The best loams have stable ''crumbs'' which
do not interfere with drainage and hold their structure for the life of the mix. Akadama is an excellent example of this type of soil. However if you look for it you can find it in most areas. It is the clay content which is the most important factor if crumb formation, so a sandy loam will not have this structure, nor will a silty loam.
In regards to soil structure, does that mean the soil that I tested (which seemed to have no or very little clay content), would be unsuitable then due to lack of clay? It came back as loamy sand.
I seem to remember reading something you said about squeezing the dirt together and if it stayed together it had good structure, but also I can't find that post anywhere so maybe I imagined it lol. If this is wrong and there is a differnt way to judge soil structure that you know of I'm all ears!

I did just have a look to see if akadama is sold near me, and it turns out there are a few places that sell it! I found both double line akadama and (maybe) triple line akadama. I also found Kanuma, but I'm unsure what the differnces between them are.
It's considered inorganic right? I wonder if it would still be worth adding something organic.
If you guys think it'll solve the potting mix conundrum then it'll be worth getting!
I have no idea how much I should add or what it's water holding capacity is like, so if any of you have advice on that that'll be great. :)
Wellington, New Zealand.

Humidity 70% - 80%, goes as low as 60%.
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Steve Johnson
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Re: Organic component's in soil mixes

Post by Steve Johnson »

Let's go back to basics with the first part of my "Are you growing your cacti in a soilless mix?" presentation (https://www.cactiguide.com/forum/viewtopic.php?t=47632):
Steve Johnson wrote: Wed Feb 08, 2023 12:37 amI went soilless back in 2012 when I moved 64 of my 68 cacti from a heavy soil-based mix to a hydroponic pumice and granite gravel mix. The benefits have been quite significant, although there may be a couple of drawbacks to this mix for some of you:
  • Pumice is easily available in the US, but not so easy in other countries. If you can't buy pumice, Perlite is second-best. Only problem there is that it floats away whenever you water. A good thick layer of gravel top dressing on your pots keeps the floaty stuff from getting all over your plants. Another viable option -- calcined clay cat litter. Either Perlite or calcined clay will work just fine as the mineral component in a soilless mix.
Contrary to what I believed until Mike just pointed it out, sandy loam is completely unsuitable. The loamy sand on your farm is also unsuitable because it doesn't contain any clay. As he said, the best structured soils are usually found at sub-soil level such as under pasture and other natural areas which have not been disturbed by agriculture -- something you won't find with commercial potting soils. This is a very good argument in favor of going soilless.

I had to remind myself about why I recommended adding organic material to soilless mixes:
Steve Johnson wrote: Wed Feb 08, 2023 12:37 am
  • The hydroponic approach is appropriate to humid or very humid climates. If your local climate is on the dry or very dry end of the scale, such a mix will dry out too quickly in the pot -- that's when you'll need a soil substitute for better water retention as the soilless mix dries out like it would in a soil-based mix.
The soil substitute would have to be some sort of organic material, and chipped/shredded tree bark would be great if it weren't for the fact that it becomes hydrophobic over the course of repeating wet-to-dry cycles. What can we do instead? Well, the answer is irrelevant -- since you live in a very humid climate, you can take the completely mineral hydroponic approach. The more I thought about it, the more I realized that there's no advantage to adding an organic component, and in fact I firmly believe it'll cause nothing but trouble for you because it retains too much water. (By the way, the Tui Performance Organics Seed Raising Mix is right out.)

Mike mentioned Akadama, so we'll compare it with pumice. From Wikipedia:
  • "Akadama is a naturally occurring, granular clay-like mineral used as soil for bonsai trees and other container-grown plants. It is surface-mined, immediately sifted and bagged, and supplied in various grades; the deeper-mined grade are somewhat harder and more useful in horticulture than the more softer, shallow-mined grades."
Okay, if you want to go that route, you'll need to buy the deeper-mined grade. If your sources in New Zealand can't tell you specifically that they're selling the deeper-mined grade (or they only sell the surface-mined grade) of Akadama, that's a deal-breaker. Even if you can find the deeper-mined grade, consider this:
  • "For all of its qualities, many bonsai growers consider the cost of akadama prohibitive or unnecessary. Still other growers claim that when subjected to cold and wet climates, the granules progressively break down into smaller particles that inhibit drainage, an unwanted characteristic of bonsai soil."
Given the cost and complicating factors involved, you're better off with the pumice you can easily buy in New Zealand.

A potful of pumice takes too long to dry out in humid climates like mine, and adding granite gravel to the mix acts as a sort of "modifier" so that it dries out in a more timely manner. I found that a 60% pumice-40% granite gravel mix is pretty much perfect. Since your climate is more humid, I'd go with a 50% pumice-50% granite gravel mix. Instead of granite, you could make it 50% coarse sand with the 1 mm-2 mm grain sizes I mentioned in my previous post. Even better, I think such a mix should work well for your cacti and succulents. Only downside is that you'll have to fertilize every time you water, but the upside for excellent growth is something I've been enjoying with all of my cacti. I'm sure you'll get the same upside with your cacti, and your succulents too.

If you'd like to go with a 50% pumice-50% coarse sand mix, here's a tip -- using a spray bottle, spray the mix just enough to moisten it. The sand will want to drift down to the bottom of your mixing container if it's dry, but if you spray the mix, it'll hang together better while you repot your plants. The mix will dry out quickly after you repot, and it'll continue to hang together as it goes through further wet-to-dry cycles. I used to struggle with my pumice and granite gravel while I was mixing it dry, but spraying it when I mix works remarkably well.
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