commercial cactus mix.. What is wrong with them.

[mikethecactusguy]

Cactus mix is a very hot topic. Most of the old timers here have their prefered personal mixes that they swear by. Different mixes for different species.
I personally have a diverse collection of plants. I have chosen to grow all of them in commercial mixes. I don't augment them with more perlite or sand or gravel. I use them as they come out of the bag. Commercial mixes are different from brand to brand and i settled on 2 specific brands that the plants thrive in best.
Is there any reason I should change them all out to have a diversity of mixes depending on the species?
Thank you
Mike M

[Steve-0]

Does your mix ever behave like commercial "peat & perlite" soil which most every store uses? By that I refer to the dry, hydrophobic nature which won't absorb water no matter what and the becomes sort of a non porous brick encasing the roots. Water just runs straight through out the bottom.

This was the primary reason I ended up here. The 3-4 cactus plants I started with nearly ten years ago came that way and ceased to absorb water unless I set the pot in a bowl of water which I knew wasn't the way to solve that.

Now I mix my own based on what I gleaned from here. So far so good.

[mikethecactusguy]

The 2 mixes I use do not become dry bricks. They stay porus and pretty loose. They will absorb water when I water, drain at a decent rate and then dry out after 3 or 4 days. I just sold off this cereus and needed to unpot it for shipping. You can see the condition of the roots and the soil. It's been in this mix for 9 months.

PXL_20210107_205541961-001.jpg (120.31 KiB) Viewed 3959 times

The ball is around 10" round.

[Steve Johnson]

Cactus mix is a very hot topic. Most of the old timers here have their prefered personal mixes that they swear by. Different mixes for different species.
I personally have a diverse collection of plants. I have chosen to grow all of them in commercial mixes. I don't augment them with more perlite or sand or gravel. I use them as they come out of the bag. Commercial mixes are different from brand to brand and i settled on 2 specific brands that the plants thrive in best.
Is there any reason I should change them all out to have a diversity of mixes depending on the species?

From what I've been able to tell, it takes about 5 years to know if a grower's practices are sound. If you've passed the 5-year mark using the same mixes and your plants are doing well, here two basic nuggets of wisdom:

• If it ain't broke, don't fix it.

• Don't mess with success.

I could never understand why some growers over-engineer their mixes based on different species.

[Not_going_to_treehab]

What commercial mixes do you use Mike?

[keith]

Is there any reason I should change them all out to have a diversity of mixes depending on the species? "

Some cactus are harder to grow than most often rotting if kept too wet that would be the one reason I can think of. Growing in the desert you probably don't have to worry about too much water in the pot for too long.

[DaveW]

Yes the problem of pots is water does not sink down to lower levels clear of the plants roots as it usually does in open ground. Neither do native soils behave the same in a pot as in your yard or garden which is the reason we have special potting soils to counteract this. Generally most cacti and Succulents will grow in a standard mix (whichever one works for you) but with those tricky on their own roots making it more porous and less water retentive by adding more grit etc may be needed.

That said most of us keep fiddling with our cactus soils over the years hoping to find the "magic elixir" that grows them twice as well as previously. There used to be an English book where the author listed dozens of ingredients for his potting soils and had a table of about 15 different combinations for different species. This never took on as most found their plants grew OK in a standard mix that suited their climate. Hot countries often prefer a more water retentive mix where cold climates often need a more porous less water retentive one that will dry out quicker.

Cacti can virtually exist in any mix provided they do not rot, since as Steve implies they are a long time dying. If your mix works OK for you why change? However as said we are all always looking for a better one.

[hiawog]

commercial cactus mix.. What is wrong with them.

It really depends on your growing conditions. Indio, CA gets less than 3.5 inches of rain each year. A commercial mix might be great there. Here in Houston where we get 50 inches per year and it's constantly humid, that ain't gonna work. Or least it doesn't for me.

I personally have a diverse collection of plants.

Same here, and I mean including tropicals, trees, flowers, etc. For me it's just cheaper and more flexible to mix up what I need based on what I'm planting. Gravel, sand, compost, peat moss, perlite....are all super inexpensive. The only pricey ingredient for me is pumice at $30/50lb.

Is there any reason I should change them all out to have a diversity of mixes depending on the species?

How diverse? I sort of see it as a spectrum....agave get a richer soil than opuntia, which get a richer soil than copiapoa...seedlings get a richer soil than adults...this is just what works best for me. In your conditions it may be totally unnecessary.

• If it ain't broke, don't fix it.

This.

[mikethecactusguy]

Thanks all.
Over the past few years I have tried 5 or 6 brands. Sungro Black Gold was too rich and expensive. We all know never to even use Miracle Grow. A few others sold through nurseries would develop into a puck in small pots or would change to a weird texture against the side of the terracotta pots.
Sego Nursery in North Hollywood sells a brand that was perfect. It absorbed just enough water, drained fast and dried out without compacting into a hard ball. I also tried Kellogg and Uni-grow. I liked buying from Sego so I stuck with that brand. The Cerus above was planted in Uni-grow. Kellogg and Uni-grow are the 2 Brands sold out here at the nurseries. I cannot buy the one sold by Sego. It's more a Los Angeles region brand.
The ingredients in Kellogg and in Uni-grow are very similar. These both seem to mimic what the Sego mix did.
As said above, time will tell. Since I'm getting used to how things grow now in the greenhouse and outside in the arrid area I will see how these mixes age in the pots.
So far after 4 months they seem to be doing well.

[K.W.]

Good evening dear cacti friends,
hi Mike,

all plants thrive in pumice!
Pumice with a little lava and zeolite is even better.
Whether cacti and other succulents, roses or lettuce.
Best water flow, ventilation, pH control, nutrient storage and delivery.
Good handling when transplanting and sowing.


Courage dear friends!


Best wishes

K.W.

[greenknight]

When I took Master Gardener training from WSU Extension about 40 years ago, that was one of the big points the Extension Agent emphasized - the average commercial potting mix didn't have nearly enough drainage material for the average house plant. It stays saturated for too long after watering, making it much too easy to over-water and cause root rot. Suggested mixing in 1/3 perlite or other grit at minimum for typical house plants. Potting mixes haven't changed much since then, mass-market potting mixes are still much too high in peat and low in grit.

[Mrs.Green]

A couple a years ago I had to repot a few plants ( not cacti) and I bought a small bag of the only available sort in the store. I did notice it was a different sort than they have had in the past and it was peatfree according to the label. It was very heavy and when opening it, it became clear that the weight came from water. I was hesitant to use it but decided to give it a try. The soil was very dark and had several pieces of decomposing woodchips in it. When this soil dried up in the pots, voila! It became a waterresistant brick. Pouring water on it, the water stayed on top of the soil if it couldn’t ‘escape’ at the sides. Unfortunately I don’t remember what was written on the declaration label apart from the peatfree part. I still wonder what it was made of though.

[mikethecactusguy]

Thanks KW and Spence.
Maybe I have just been lucky. When I lived in Los Angeles I would cover larger plants with plastic bags during extended rain days. I never worried about small pots. If I had any smaller pots that I felt were susceptible to rot I would just move them under the deck for cover. Usually within a few day the Sun would be out the daytime temps would get into the 60's and 70's and the terracotta would dry up.
Now here in the desert it's completely different. Even here in winter, if I water Monday, by tuesday afternoon early wednesday all the 3" to 6" pots have dried out . The larger pots seem to be controlled by the actual plant. If the plant is growing and blooming, it dries out quickly.
Spences mention of weight is interesting. I have noticed over the years some bags weigh a lot more than other. The 2 brands I mention above come in 1ft cubic size. Which to me is not accurate. A cubic foot is 12" x12" x 12". I have to assume it's based on a compressed size since the bag is a lot larger than that. They weigh around 25 lbs. When I open a new bag, the mix looks like it maybe "wet" but as soon as I remove it from the bag it will turn "grey". I have used these brands off and on in Los Angeles over the years. These have never dried out to impenetrable blocks. There have been other brands I tried that did. I found the issue the worse with 2" and smaller pots.
Mike M

[Steve Johnson]

Hi Mike,

I just posted a long-overdue presentation at the Cultivation forum, and you may find this interesting:

http://www.cactiguide.com/forum/viewtop ... 25&t=45833

While terracotta might've been okay for Benedict Canyon, evaporation through porous clay is working against you in the dry climate of Indio. IMO, you should seal your terracotta pots so that you don't have the evaporation problem. Not sure if you could go soil-less with straight pumice, but you may be able to lean out your commercial mixes with more pumice or Perlite. Yeah, I'm not a fan of Perlite, but that's an option if your bigger pots are too heavy for you going with pumice. The downside to Perlite is that it's a floaty pain in the backside, although a good thick layer of gravel top dressing will keep it from floating away whenever you water.

If you decide to seal your terracotta pots, unfortunately you'll have a big job ahead of you -- unpot each and every plant, clean the pots thoroughly, then seal inside and out with UV-resistant acrylic paint after the pots are dry. Good news for your cacti is that you have plenty of time between now and when the growing season begins in the spring. And when you unpot them, you'll be able to inspect their roots and see if the root systems are looking good. If you're sealing the pots for your succulents too, any winter-growing succulents you have should be fine as-is until you seal their pots while they're dormant in summer. For anything else you'd be repotting this winter, your Melos are the only cacti that'll need some light watering 2-3 weeks after they're repotted. Other cacti showing touches of new apical growth might like a sip as well, although I'd go the "better safe than sorry" route and keep their roots dry until they fully wake up in early spring.

[mikethecactusguy]

Thanks Steve.
The issue I am facing is that they did not go to sleep. Daytime temps in the Greenhouse of 85 to 100 degrees. They continue to grow. I tried to withhold water in November. The stress they showed 30 days later was not good. I went back to watering and they all started to grow and bloom.
Humidity During the day drops to 10% and rises to about 50% at night. I have a 12" fan running 24hrs a day to make sure there are no stagnant air spots in the greenhouse.
As for sealing all the pots. I tried sealed pots with some of the plants. I was sad to find that those were the ones that developed root rot. I honestly would prefer having to monitor and water more than chance losing a plant to rot. I do follow the better safe then sorry path still and find I sometimes underwater the larger plants in the collection. I know cactus are different than Tropicals but I find that even cactus will tell you when to water by how they look.