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I am seeing some gritty mixes for succulents and I cannot find any info on the product regarding it usage.. Will succulents or cactus do well if they are placed in those gritty mixes?

Here are gritty mixes:

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4-K
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I suspect what you are seeing in the first picture is a topdressing. Not the actual soil it is planted in. The second could also be a top dressing, but some people do plant some succulents in pure pumice or scoria (lava rock). This will depends on the succulent. The average succulent will not be happy in pure pumice. It will need more water and nutrients than you can provide in pure pumice. If you use straight pumice, you will need to feed and water your plant more often than you would in a soil with more organic material.

A good generic recipe that work for most succulents would be 65-75% inorganic aggregate like pumice, scoria, granite,... and 35-25% organic matter like peat, coconut coir, bark,...

There are a millions of recipes you could try. You will need to find the one that works best for you and your plant. Some plants want a more gritty mix like Lithops and there are others like the Echeveria in the first picture that wants more organic matter. This also goes for you. Are you the type of person to over-water? If so, you want a mix that is more gritty. If you are more of the ignore your plant type, you want a more organic blend.

My business is making craft and custom potting mix. I spent three years testing our succulent blend. Trying to make a blend that works best for most people. But, still have to make variations for different clients, because everyone is different. All plants are different.

A recipe that I don't use, but many many succulent growers do, is buy a bag of Cactus and Succulent Mix & a bag of perlite. Mix these two 1:1 or 50%-50%. This seems to work for many people. Most Cactus and succulent potting mixes on the shelf are good for regular plants, but absolute trash for most succulents. They use cheap filler, like sand. Don't use sand. They never add enough inorganic matter like perlite, because it is more expensive for them to make.

GardenGems
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  • I am thinking of garden soil + Pumice + cactus mix + vermiculite in equal parts. – 4-K Jan 17 '20 at 10:08
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    Just stick to the the pumice and the cactus mix. Vermiculite is a flat substance that holds excessive amount of water. It does not provide aeration or drainage, just holds water. Garden Soil? Why? It may harbour disease. Depending on what it is composed of it might hold too much water, eg clay soil. Why not stick to just the cactus mix and the pumice? – GardenGems Jan 17 '20 at 23:57
  • silica sand or Pumice? My garden soil is mix of soil and organic material and compost.I will stick to cactus mix. But I am finding silica to be much cheaper than pumice. What about stone gravel? Which of these three is the best? – 4-K Jan 18 '20 at 16:28
  • First Pumice. Then it's a toss-up between Very Coarse Silica Sand & Gravel. Pumice has lots of pores that are able to trap water and nutrients for the plant to use even if the soil dries out completely. It also does the opposite when the soil is completely saturated, it holds pockets of air for the roots to breath. It also does not compact. Most sand will compact, unless it is almost the size of small pumice. Gravel works just fine for drainage and a some aeration. Make sure its not too big. 3-5mm (1/8"-3/16") no bigger and not much smaller. – GardenGems Jan 18 '20 at 18:17
  • Pumice it is then. But there are two sizes available:. 2-4mm, and 4-8 mm. – 4-K Jan 19 '20 at 08:29
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    I would use the smaller size 2-4mm. Otherwise the peat or coir or whatever the brown matter is will get washed down to the bottom of the pot when you water. It will create a damn of wet/muddy brown matter that will rot the roots. You need the size to be something that will blend in easy, but not be so small it creates a damn itself. You may buy the pumice and discover it actually has a lot of bits that are smaller than 2mm, sandy/dusty. In that case the pumice will need to be screened. Buy some 3mm (1/8") screen and pour the bag content through it. – GardenGems Jan 19 '20 at 18:50
  • I have found something better but not sure about the size. The coin size is 27mm. People are praising it with no dust and size being excellent. can you take a look? It seems they are much bigger than 8mm. https://images-na.ssl-images-amazon.com/images/I/81NnlzTaBVL._SL1500_.jpg – 4-K Jan 20 '20 at 17:04
  • It's too large. It nice and clean, but too large for little succulents. All the peat will be washed down to the bottom of the pot leaving you a top of just rock. I would buy the 2-4mm and sift it. – GardenGems Jan 20 '20 at 18:36
  • Can I not break pumice stones? – 4-K Jan 23 '20 at 10:19
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    You can crush it, then screen out the smaller particles like the dust you will create. Crush the pieces that remain to large. Its a lot of work, but you already made the investments, so go for it. – GardenGems Jan 23 '20 at 10:26
  • yeah cause the price of 2-4mm was same as this one and the reviews were saying that there is absolutely no dust in this. I will update once I get the packet. – 4-K Jan 23 '20 at 10:31
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Soil mixes for succulents are only part of the picture when discussing successful propagation and growth of succulents.

Pot size and construction, drainage, local weather (if you live in a humid area you'll need a more open mix than someplace with heat and low humidity which wants to retain more moisture. The actual constituents of the mix need to be considered, if you are growing succulents that dry out completely, avoid peat. It is very difficult to re-wet once it dries out. Coir is a reasonable substitute.

The current thinking amongst collector cactus growers are to use a more mineral mix (90/10) for desert plants and adjust from there depending on the native conditions. Some use a 100% mineral mix for some species, but you have to pay attention to feeding. There is little nutritive value in mineral mixes.

Tim Nevins
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