Top dressing for succulents

[conolady]

I don't know about you guys, but I find bickering tiring, boring and a waste of time. What is worse, it's putting people off posting in this Forum. Me included.

[Peter]

I use a 50-50 mix of fine washed grit (approx 3mm) - and John Innes No 3, with a nominal amount of Tesco cat litter added. This latter to help mop up and gradually release excess water. I've used this mix for many years for all my plants and have been very satisfied with the results.

Back to top dressing; I take a degree of pride in the appearance of my plants and top dressing is in my view, essential. I don't need to see the compost to know whether it's dry or wet. My standard mix is free draining and I tend to water every fortnight or so.

[Astro]

Any ion exchange considerations aside, a large concern with a potting mix is to make sure it retains an adequate but not excessive amount of water. In this regard, the same soil can act very differently in a pot vs in bulk (e.g. out in the wild). Here is an excellent post on this topic by one of our forum members:

https://www.cactiguide.com/forum/viewto ... 38#p122559

[conolady]

Any ion exchange considerations aside, a large concern with a potting mix is to make sure it retains an adequate but not excessive amount of water. In this regard, the same soil can act very differently in a pot vs in bulk (e.g. out in the wild). Here is an excellent post on this topic by one of our forum members:

https://www.cactiguide.com/forum/viewto ... 38#p122559

That is really interesting. Thanks for posting.

[Chez2]

I have been reading this thread with interest. Do you think the slimy white stuff on the surface of the growing medium that el48tel mentions could be mould? If potted plant soil is over watered it can get a covering of saprophytic fungus.

[el48tel]

I have been reading this thread with interest. Do you think the slimy white stuff on the surface of the growing medium that el48tel mentions could be mould? If potted plant soil is over watered it can get a covering of saprophytic fungus.

No chez2 -- definitely not mould - was the red stuff some of which was less degraded but was squash-able into the stuff which had degraded

[D^L]

One really good point for newbies is that when we talk of "cat litter" we mean one specific type. There are many types made of paper or other media that do not retain their structure over the years we expect a succulent to be in a pot.
The principle brand in UK is no longer made but there are others.
BUT don't use any old cat litter.
Cheers
David Lambie
Bristol

[D^L]

I have always assumed that angular grit and "sharp sand" tend to pack with larger gaps round them than spheres do, but I don't know any experimemtal evidence that shows that; so if you turn some up Ralph, would be interesting.
I feel that much of our "knowledge" about how to grow is anecdotal and there is little supporting evidence for many of our rules. For instance, whether lime is good or whether nitrogen in fertiliser is bad or... Many strongly held opinions but little evidence. More such evidence would be good. I don't mean evidence like "one old chap told me..." but scientifically sourced evidence.
Cheers
David Lambie
Bristol

[el48tel]

.....................
I feel that much of our "knowledge" about how to grow is anecdotal and there is little supporting evidence for many of our rules. For instance, whether lime is good or whether nitrogen in fertiliser is bad or... Many strongly held opinions but little evidence. More such evidence would be good. I don't mean evidence like "one old chap told me..." but scientifically sourced evidence.
Cheers
David Lambie
Bristol

I know I've been accused of being sarcastic etc etc ..... but this point --- well made by David ---- is exactly the place at where my thinking started. I have even read some of the sister journals from France and Germany to try and understand the thinking behind some of the Compost concoctions.

[peter831shaw]

Hi David and others,

I was taught back in the day to use sharp river sand in my canning mix (not necessarily cactus mixes) for better drainage.

I grow lots of veggies in LECA with an ebb and flood aquaponic systems and have tried another "brand" that was full of various sizes and shapes. The plants did not do as well and I prefer the round LECA better.

On another note, we are going to be building a slow sand filter to remove pathogens from our hydroponic leachate so we can reuse the water.

The sand has to be angular, as shown by researchers at UC Davis. It provides drainage and a surface for the Schmutzdecke a biofilm of odd microbes to do their mysterious work.

Peter