A cactus mix idea

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Steve Johnson
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A cactus mix idea

Post by Steve Johnson »

At the risk of hijacking someone else's thread, I'd like to break out a new one here. This comes from a comment prompted by Ian:
iann wrote:Pumice is rock. CEC is virtually zero. Porous is not the same as CEC, which measures how well a substance holds nutrients (without water!) in a form available to plants. Degrading to release trace elements is not the same as holding nutrients for roots. Clay holds nutrients available for the roots and most organic materials hold even more. Most other things hold virtually none and you need to provide the nutrients in soluble form or there aren't any.

That CCC soil mix obviously has some fibres in it, but I can't tell what they are. And something that looks like pumice or perlite, but it seems too dark for perlite. There are plenty of experienced succulent growers and sellers that use (and sell!) awful soils. The cost difference can be compelling, not least because fluffy organic soils are so light while rocks and dirt are so heavy. Loam soils are easy to find but locating a consistent source in commercial quantities not so easy. It also seems like regulations in the US right now make it difficult to bag and sell anything that would be considered a good quality loam.
Let's review. This is a sample of cactus mix from the California Cactus Center:
Image
Now, the dirt in my yard comes from Los Angeles (southwest of downtown), and it supports generally good plant life in the area. For example, my vegetable garden thrives on squash, tomatoes, and peppers (gotta love those Jalapenos and Habaneros!). Obviously, the dirt on its own will not provide sufficient drainage for cacti. So what I'm thinking is this: 50% soil from the yard, 25% gravel (perhaps pea gravel?), and 25% pumice. For Astrophytums, Turbinicarpi, a Cephalocereus senilis, and a Melocactus matanzus, it may be advisable to adjust the ratio more in favor of pumice.

This is only a rough idea at this point, so if I'm going in basically the right direction, I would greatly appreciate any suggestions on the best mix ratios I'd be using. If it turns out that my own mix would in fact be a better replacement for the CCC cactus mix, then I'll start afresh at the beginning of spring.

Thanks!

Steve
Tony
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Post by Tony »

Your not really gaining anything using gravel except weight, I would leave out the gravel and just use the pumice 50/50 or go even highter with the pumice if you still want faster drainage.
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Steve Johnson
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Post by Steve Johnson »

Tony wrote:Your not really gaining anything using gravel except weight, I would leave out the gravel and just use the pumice 50/50 or go even highter with the pumice if you still want faster drainage.
I was wondering about the gravel, so I guess it would make more sense to keep it at 50/50 garden soil and pumice. For the Astrophytums, Turbs, etc. I know they should drain faster than most other cacti, so perhaps 60-75% pumice with less of the soil. Of course the push-pull is that less soil means less nutrients available for cacti, so I'd have to add fertilizer at least once a year. However, I wouldn't have a problem doing that given how small (and therefore more manageable) my collection is.

While we're at it, I have a granulated time-release fetilizer from the CCC. Here's what is on the label:
Image
Does this stuff look like it's any good, or is it another example of a supposedly experienced C&S nursery selling an awful product? I kinda hate to sound like I keep bagging (pun intended) on the CCC, but I also don't take anything for granted. (Granite? Ooh, there goes another pun!) By the way -- regardless of any skepticism I may entertain concerning the CCC's cactus mix or fertilizer, I continue to be pleased about the variety and quality of the cacti they have on hand. I wouldn't hesitate to buy more plants from them again.

Other thoughts, anyone?
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Re: A cactus mix idea

Post by RichR »

Steve Johnson wrote:Now, the dirt in my yard comes from Los Angeles (southwest of downtown), and it supports generally good plant life in the area. For example, my vegetable garden thrives on squash, tomatoes, and peppers (gotta love those Jalapenos and Habaneros!). Obviously, the dirt on its own will not provide sufficient drainage for cacti. So what I'm thinking is this: 50% soil from the yard, 25% gravel (perhaps pea gravel?), and 25% pumice. For Astrophytums, Turbinicarpi, a Cephalocereus senilis, and a Melocactus matanzus, it may be advisable to adjust the ratio more in favor of pumice.

This is only a rough idea at this point, so if I'm going in basically the right direction, I would greatly appreciate any suggestions on the best mix ratios I'd be using. If it turns out that my own mix would in fact be a better replacement for the CCC cactus mix, then I'll start afresh at the beginning of spring.

Thanks!

Steve
Steve, Does this blend drain well? If I use that much soil (loam) in my mix it won't drain adequately; tends to get clogged. I found I needed to cut the soil component down to 30-35% at most. Maybe my loam is finer than yours, though.
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Post by iann »

The fertiliser mentions Iron, Manganese and Zinc. I wonder if it has any other trace elements. Not so important if you use a mineral soil though, because they will usually be available from the soil itself or the rocks you add.

Seems quite strong to me to be using that quantity every three months. Might want to use less for slow growing plants like most potted cacti. You have to work hard to underfeed a cactus, but you can easily overfeed one.

Loam varies a lot. The loam I use is quite sandy and I find I need a little more aggregate than soil to get the drainage right. A denser soil would need more. In a very hot dry climate, you can almost ignore drainage since the soil will (should!) dry out so fast that it doesn't really matter whether it retains air or not. Maybe an advanced technique best left until you can resist watering at the wrong times?
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Steve Johnson
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Post by Steve Johnson »

RichR wrote:Steve, Does this blend drain well? If I use that much soil (loam) in my mix it won't drain adequately; tends to get clogged. I found I needed to cut the soil component down to 30-35% at most. Maybe my loam is finer than yours, though.
The dirt in my garden seems to be taking a long time to dry out with all the rain we've been getting. So I'm afraid you're right -- 30% soil and 70% pumice. The idea doesn't thrill me at all, and it looks like I'm going back to square one with the CCC's cactus mix if I can find out a better one.
iann wrote:The fertiliser mentions Iron, Manganese and Zinc. I wonder if it has any other trace elements. Not so important if you use a mineral soil though, because they will usually be available from the soil itself or the rocks you add.

Seems quite strong to me to be using that quantity every three months. Might want to use less for slow growing plants like most potted cacti. You have to work hard to underfeed a cactus, but you can easily overfeed one.

Loam varies a lot. The loam I use is quite sandy and I find I need a little more aggregate than soil to get the drainage right. A denser soil would need more. In a very hot dry climate, you can almost ignore drainage since the soil will (should!) dry out so fast that it doesn't really matter whether it retains air or not. Maybe an advanced technique best left until you can resist watering at the wrong times?
The CCC's fertilizer seems to be matched with what they're using for their cactus mix. What I find strange is that the label on the fertilizer says every 3 months, but the CCC's website says fertilize once a year. That makes a lot more sense for a granulated time-release fertilizer, so I don't know why there's a discrepancy between their labelling and what they have on their site. I may actually look around for a liquid fertilizer anyway -- I put gravel top dressing on my pots, and it seems like it would be a pain to have to take off the gravel, mix the granulated stuff into the soil, then put the gravel back on. Yeah, I know it's only once a year, but I don't like messing around with things too much, and I really like the look of gravel on top of my little C&S collection.

I don't want to experiment on my cacti unless I know what I'm doing. Frankly, I have no knowledge on the ins and outs of soil composition, so the whole garden soil/pumice mix idea seems more and more like it's a bad idea. The CCC's cactus mix may not be the best, but it seems at least adequate for now. I've been keeping the rain situation under control, so dryness in winter (or lack thereof) is not an issue. Don't have to make any changes to a new mix for now, so I'll look into it at my leisure, then we'll see if there are any better alternative for a start on the new growing season.

By the way, Darryl on the forum has been really helpful. I'll ask him if he'd be kind enough to let me snail-mail him a sample of the CCC's cactus mix. Perhaps a little soil analysis could help him figure out if the CCC's mix is good, or if he can give me a better recommendation. Since CoronaCactus Gardens isn't a huge distance from my area, I think Darryl could give me some educated advice.

Thanks, guys, and let me know if you have any further thoughts!

Steve
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Post by CoronaCactus »

Hi Steve,
Looking at the pic of CCCs mix, i'd be surprised if it was much different that a bag of SuperSoil cactus mix (red bag) with maybe a bit more pumice/perlite added. In my opinion it needs much more pumice added!

We have used the SuperSoil mixed with pumice at 50/50 but have moved onto more of a 60/40 70/30 ratio. We grow so many plants thats its hard to impossible to monitor each plant, so we're moving more and more towards mineral mixes with very low amounts to none of any organic matter. We feed on a regular basis so for us there is no need for anything additional in the mix other than trace elements that DG et al. provides.

Moving to a pure mineral mix or with a VERY low % of organics and regular liquid soluable feeding, the chance of rotting a plant dramatically decreases. The downfall to this is the physical weight increases, but i build strong benches ;)

Personally, i like to keep it as simple as possible with 2-3 components in the mix for everything.
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Post by Steve Johnson »

CoronaCactus wrote:Hi Steve,
Looking at the pic of CCCs mix, i'd be surprised if it was much different that a bag of SuperSoil cactus mix (red bag) with maybe a bit more pumice/perlite added. In my opinion it needs much more pumice added!

We have used the SuperSoil mixed with pumice at 50/50 but have moved onto more of a 60/40 70/30 ratio. We grow so many plants thats its hard to impossible to monitor each plant, so we're moving more and more towards mineral mixes with very low amounts to none of any organic matter. We feed on a regular basis so for us there is no need for anything additional in the mix other than trace elements that DG et al. provides.

Moving to a pure mineral mix or with a VERY low % of organics and regular liquid soluable feeding, the chance of rotting a plant dramatically decreases. The downfall to this is the physical weight increases, but i build strong benches ;)

Personally, i like to keep it as simple as possible with 2-3 components in the mix for everything.
Ah, now we're getting somewhere! There is so much I've forgotten over the years, but I seem to recall that most desert plants thrive on clay- and mineral-type soils, and organic materials don't factor much into it. What you said makes a whole lot of sense, so you and Ian pretty much confirmed what I suspected about the CCC's cactus mix.

I could up the ratio of pumice to the CCC's mix. But I'm not satisfied with "adequate", in fact I think I could do much better. I can easily understand the benefits of mineral soil, and I'm attracted by the idea of what this could do for my cacti. Even though I'm constrained by having such a small collection, my plant bench is 5' by 1 1/2' as a virtue of the fact that the heaviness of mineral soil won't be a problem.

Since I'm a total newbie when it comes to dealing with proper cactus mixes, I could use some advice. First, here are the cacti I have in my collection:

Astrophytum asterias, capricorne v. senilis, and myriostigma v. quadricostatum
Cephalocereus senilis
Copiapoa hypogaea
Echinocereus pectinatus v. rubrispinus
Espostoa lanata
Gymnocalycium ochoterenae ssp. vatteri
Mammilaria microcarpus and spinossissima
Melocactus matanzus
Eriosyce senilis
Opuntia articulata
Sulcorebutia rauschii
Turbinicarpus macrochele v. polaskii, schmiedickeanus (v. macrochele or ssp. schmiedickeanus?), and pseudomacrochele ssp. lausseri

I really like your idea of keeping it as simple as possible with 2-3 components in the mix for everything. Even with a small collection, I won't be able to stay up enough on the esoterica of trying to manage a half-dozen different mixes. So what I'm looking for is a basic mix that's suitable for most of my cacti. For certain cacti that need more drainage (such as Astrophytums, Turbs, etc.) I hope that adding something appropriate to the basic mix would be rather easy (yes, simplify!). I suppose that adding pumice if needed would be okay, although if it adds nothing to the nutrient value for cacti, I'd prefer something better. (I'd love it if I could do away with fertilizer entirely!)

If I make my own cactus mix, 20 pounds should be plenty to keep me going for a few years at least. I could use some recommendation on the components I need to get, as well as their ratios for mixing. Also, since I'm not up on where the right sources are, it would be a great help if I can easily find what I'm looking for in the greater Los Angeles area. I have the feeling that going over to a mineral soil will do my cacti a world of good, so I very much appreciate any assistance to go in the right direction.

Thanks!

Steve
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Lots of L.A. growers go to near 100% pumice

Post by amanzed »

Now... I'll say up front that I grow more succulents than I do cactus. (Maybe 700 to 300? That's a guess.) But the more I circulate around L.A. growers, the more I hear people growing with high pumice quotient, often 100%. You have to feed more often but—as I overheard Miles Anderson telling a customer at his 2011 Inter-City booth...

Growing in all or mostly pumice gives you control.

I have settled on about 85% pumice by volume as a baseline, using more or less depending on the sensitivity of the plant. Some plants do great with 95% or 99% pumice with just some added mycorrhizae (I use Plant-Tone which has beneficial microbes), or even without. Others show signs of starving, in which case I add 10% SuperSoil, boiled garden loam or even decomposed granite (my supply is more like mineral dirt than crushed rock).

Whittier Fertilizer has decent prices on pumice. I buy my pumice there under the name "Dry Stall". It's smaller grains than what they sell under the name "pumice", but I actually like the smaller size and it's even cheaper.
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Re: Lots of L.A. growers go to near 100% pumice

Post by Steve Johnson »

amanzed wrote:Now... I'll say up front that I grow more succulents than I do cactus. (Maybe 700 to 300? That's a guess.) But the more I circulate around L.A. growers, the more I hear people growing with high pumice quotient, often 100%. You have to feed more often but—as I overheard Miles Anderson telling a customer at his 2011 Inter-City booth...

Growing in all or mostly pumice gives you control.

I have settled on about 85% pumice by volume as a baseline, using more or less depending on the sensitivity of the plant. Some plants do great with 95% or 99% pumice with just some added mycorrhizae (I use Plant-Tone which has beneficial microbes), or even without. Others show signs of starving, in which case I add 10% SuperSoil, boiled garden loam or even decomposed granite (my supply is more like mineral dirt than crushed rock).

Whittier Fertilizer has decent prices on pumice. I buy my pumice there under the name "Dry Stall". It's smaller grains than what they sell under the name "pumice", but I actually like the smaller size and it's even cheaper.
Ooh -- I wish I could consider pumice. Unfortunately I have a plant bench with smaller pots (mostly 3" - 5") sitting on the front porch of my second-floor apartment. We're exposed to some pretty high winds, and those pots with so much pumice are asking for a crash to the ground. Even though the mix I'm using from the California Cactus Center needs to be replaced with something better, at least none of my cacti have been blown away. If I go over to mineral soil, heavier pots would give me some extra peace of mind.

Thanks for your recommendation, though. I do appreciate the good people we have here at the forum!
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Post by A. Dean Stock »

The fertilizer mentioned above looks a lot like the various fertilizers commonly available for orchids. Most of them are not very effective for either cacti or orchids when based on Urea as this one is. In a cactus mix that dries out rapidly, most of the urea is not going to be available to the plant. I'd suggest a liquid fertilizer based on a nitrogen source other than Urea (Nitrate;Ammonia), and higher in trace elements depending on your mix. The "MSU" (Michigan State Univ.)fertilizer designed for Orchids works well for cacti. I would use it at about half the rate suggested for orchids or house plants if your plants are in good growth . I doubt that you would need to fertilize your plants more than twice a year. I always fertilize in the spring once the plants are growing well. I believe that changing the pH slightly to the acid side (if it is not already) after mixing with your water source is beneficial.
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Post by Steve Johnson »

A. Dean Stock wrote:The fertilizer mentioned above looks a lot like the various fertilizers commonly available for orchids. Most of them are not very effective for either cacti or orchids when based on Urea as this one is. In a cactus mix that dries out rapidly, most of the urea is not going to be available to the plant. I'd suggest a liquid fertilizer based on a nitrogen source other than Urea (Nitrate;Ammonia), and higher in trace elements depending on your mix. The "MSU" (Michigan State Univ.)fertilizer designed for Orchids works well for cacti. I would use it at about half the rate suggested for orchids or house plants if your plants are in good growth . I doubt that you would need to fertilize your plants more than twice a year. I always fertilize in the spring once the plants are growing well. I believe that changing the pH slightly to the acid side (if it is not already) after mixing with your water source is beneficial.
Dean
Wow -- so much I don't know, but this forum is a real education. I take diligent notes whenever I can, and at least I'm willing to learn.

I was looking for a liquid fertilizer to replace the CCC's stuff anyway. If you're recommending the MSU fertilizer, I believe what you're talking about is the following:

http://www.repotme.com/orchid-fertilize ... index.html.

The tap water here in L.A. is pretty hard, so I think it would be slightly acid. Is that correct, or do I need to acidify?

Also, I'm debating the issue of cactus mixes. There are 3 possibilities in the running: 1. Add a significant amount of pumice to the CCC's cactus mix. 2. Use a 60/40 - 70/30 ratio of pumice to SuperSoil (may end up being the same thing). 3. Go over to a mineral soil. With options 1 and 2, regular feeding is a requirement. I have no problem with that as long as I know the right fertilizer to use (sounds like MSU to me). However, I'm feeling more inclined toward a mineral soil, and that may be a real plus being in a southern California climate. If that's the case, would fertilizer be needed at all? These are all questions I'm pondering as I try to figure out what seems to be the best solution for me.

As I'm gaining a little more knowledge on all this, I must say that I'm a bit disappointed about how many C&S nurseries don't seem to know much about the cultivation of their own plants. I'll be happy to visit the CCC for more cacti. But for soil and fertilizer requirements, I'll look elsewhere.

Thanks so much for your help!
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Post by iann »

Hard water is almost always alkaline, sometimes very alkaline. Tap water is almost always alkaline whether it is hard or not, because the water companies dose it to prevent corrosion, but soft tap water will only be slightly alkaline. Rainwater will be mildly acid except in very unusual conditions. Rainwater downwind of a nice coal-fired power station will be more acidic but not so much these days.

You'll need fertiliser sooner or later. Most soil will contain some fertiliser and you can get away with just repotting every 2-3 years for slow growing plants, but a little dilute fertiliser is nearly always helpful. Dilute!

Raw coir won't include much nutrients, although commercial coir-based potting soils will. Any bagged potting soil will contain masses of fertiliser, comfortably a year or two's supply for a cactus, but you can still add a little dilute fertiliser after the first few months. Sandy or stony loam soils dug up for a potting mix will contain some nutrients but not a lot. Use dilute soluble fertiliser after the first few months.

Potting mixes without organic ingredients or loam will need to be fertilised frequently with very dilute fertiliser.
--ian
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Post by Steve Johnson »

iann wrote:Hard water is almost always alkaline, sometimes very alkaline. Tap water is almost always alkaline whether it is hard or not, because the water companies dose it to prevent corrosion, but soft tap water will only be slightly alkaline. Rainwater will be mildly acid except in very unusual conditions. Rainwater downwind of a nice coal-fired power station will be more acidic but not so much these days.

You'll need fertiliser sooner or later. Most soil will contain some fertiliser and you can get away with just repotting every 2-3 years for slow growing plants, but a little dilute fertiliser is nearly always helpful. Dilute!

Raw coir won't include much nutrients, although commercial coir-based potting soils will. Any bagged potting soil will contain masses of fertiliser, comfortably a year or two's supply for a cactus, but you can still add a little dilute fertiliser after the first few months. Sandy or stony loam soils dug up for a potting mix will contain some nutrients but not a lot. Use dilute soluble fertiliser after the first few months.

Potting mixes without organic ingredients or loam will need to be fertilised frequently with very dilute fertiliser.
Well, you're so kind to put up with my endless questions. I've never had to think about the pH of our tap water, so it's another bit of education I should have.

As I pursue the idea of going to a mineral soil, it became apparent that fertilizer still needs to be used. I'm thinking about what you said, so I have more to learn about when it concerns what the heck I'm trying to do.

At the risk of wearing out my welcome, I'll post a new thread on the cactus mix I've been trying to come up with. If you'd like to have a look, that would be excellent. Then I'll have to take off my training wheels and put an experiment into practice. It'll be interesting to see what happens.

Thanks so much!
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Post by A. Dean Stock »

Your water is very likely to be at least slightly alkaline. That if the correct MSU fertilizer at RePotme. I'd buy the one for tap water and also get the granules not the liquid unless you just like paying them for their water and higher shipping weight. The fertilizer may lower your final watering solution pH some but I'd test it to be sure. Use a very dilute fertilizer solution (like 1/2 tsp/gal. of the granular mix to your watering solution. If your water is very hard with a heavy load of salts you might be better off using R/O water, in which case you would buy the fertilizer designed for RO. Your local water company will supply you with water hardness and pH (usually).
Dean
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