Comparison of substrate types for germinating cactus seeds - which works best?

I'm never sure what sort of substrate should be used for germinating cacti. So here I am starting an experiment to run over the next few months. I have sown 3 types of seeds - Astrophytum Capricorne, Gymnocalycium Damsii and Echinocactus Grusonii - each into 2 separate substrates, one a standard bought potting compost, and one a home-made mix of 50% coconut fibre, 25% river sand and 25% perlite. The former will have a good balance of nutrients in it, suitable for potting up adult plants. The latter will have very low nutrient content, but cactus seeds should be able to start growing without too much nutrition. I've found that a nutrient-rich substrate leads to quite a lot of moss growing under the grow lights. This moss is not necessarily a problem but it can rather swamp the small seedlings in the early stages. I aim to avoid this problem altogether with the home made subsbtrate, and it will be interesting to see how the two compare.
I'm sorry everyone if you were looking for an answer to the question "what substrate should I use to germinate cactus seedlings" then you will have to wait a few months until I have some results! I will provide an update when I open the bags, and may provide an update before then if there is anything interesting to show.
Do please subscribe to my channel and click the notification bell, and please like this video or post a comment or question below. I'm enjoying learning about growing cacti and other succulents so I hope I can share this enjoyment for the benefit of others too.
Happy cactusing everyone! :-)

[@desertplantsofavalon]

This is a BRILLIANT experiment to try growing the seeds with the different substrates, and its going to be really amazing to see what the results will be with their growth rates between all the different substrates, so exciting to get sowing seeds and so looking forward to seeing the results in the coming weeks, and your grusonni you have grown from seed is looking awesome, thanks so much for sharing this wonderful seed sowing substrate experiment with us Donald, and sending you lots of love and happiness and PLANT POWER from Hans and me to Northern Spain for a wonderful Thursday XXXX

[@DFJA01]

Thanks so much for your comment Lyn! I've been stuck with these seeds for a couple of months, waiting for warmer weather but also unable to decide what substrate to grow them on (analysis paralysis!) and doing both was my solution to getting them started - I use a similar technique when I can't decide between 2 flavours of ice cream hahaha :-) :-) :-). I'm really excited to get some more Astrophytums going, and the Gymnocalyciums are totally new to me so I don't know what to expect. The Echinocactus Grusonii I showed was overwintered in my grow tent so not allowed to go dormant, the other six are also doing very well but are a little bit smaller. I should have showed them side by side for comparison.
Lots of cactus love to you and Hans from northern Spain! :-)

[@ZiggySearchfieldCactus]

Nice one Donald 🙂 Be interesting to see what happens. I bet you check on them before you have a cuppa in the morning 😁 Have a lovely evening 🙂🙂🌵🌵

[@DFJA01]

Many thanks Ziggy. My cacti do tend to get rather over-checked, I have to confess. Especially now that some larger plants are growing very noticeably!
Have a great Friday. 🙂💚🌵

[@vanessaamber2608]

Oh yes!

[@UrbanHafner]

Now I am super tempted to buy some seeds and give it a try, too!

[@DFJA01]

Many thanks for your comment. Seeds are very cheap compared to adult plants or even seedlings, and with luck you end up with a lot of plants. I can thoroughly recommend giving it a try. There's definitely something very satisfying about growing cacti from seeds, although expect to have some disappointments along the way. It's not hard to germinate cacti but it can be harder to keep the seedlings going until they reach a large enough size to be robust.

[@UrbanHafner]

@@DFJA01So far I've gone the "natural" route and just sprinkled the needs from my Echinopsis in their seeds and I was able to grow surprisingly many that way. 😆 I guess it's time to do it the right way now.

[@DFJA01]

@@UrbanHafner That will probably work quite well if you have the right climate. I still need to use a heating mat at this time of year, and have really just followed what many other videos show. But I couldn't find a huge amount of discussion about substrate type, so decided to do this experiment to find out for myself.

[@UrbanHafner]

@DFJA01 nah. South of Germany doesn’t really help. Still expecting temperatures below zero here. ;) You just have to start late.

[@vanessaamber2608]

Why do you have to put them in a sealable bag?

[@DFJA01]

Thanks for asking a brilliant question, which I didn't cover in the video. When cactus seeds germinate they need a warm, humid environment, and a good way to do this is to put them in a bag on a heating mat (at least in Spanish winter). By using a sealable bag, the moisture stays in for the long term and also keeps things like fungus gnats out, as well as reducing the risk of contamination that could cause sensitive seedlings to rot. I've also tried "take away tech" which is another popular method.

[@vanessaamber2608]

That's interesting.....
Love, love, love Cactus😊

[@DFJA01]

@@vanessaamber2608 So glad that you love cactus ❤️❤️❤️