The results of this adapted technique speak for themselves; this is a great way to start seeds of Trichocereus and one would assume all cacti. Below is the basic technique which has been edited and modified slightly by us, you could vary it in subtle ways that suit your climate and environment.
The Takeaway Tek
So take some cactus or seed raising mix and sieve it to remove large rocks and (ugh) sticks and bits of wood (why do they put that rubbish in cactus mix?). I use maybe 30-40% coco peat mixed and sieved as well.
Put a thin layer 2-3cm or so in a microwavable plastic takeaway container (just buy from supermarket). Tamp the mix down into a level layer using something flat.
Add just enough water using a sprayer so its just damp, too much moisture is bad. We use a bit of seaweed solution too. We find for a 500-600ml takeaway container adding 25-50ml of water is more than enough, find what works for you.
Put the lid on loosely and microwave for 3 minutes on high. Give it another minute then remove and allow to cool. (you can actually skip this step if you want, I tend to like working with good bacteria and fungi instead of nuking everything, try both and see what works for you)
Once cool take a permanent marker and write the date, species you are sowing, what treatments you are using (like seaweed, biochar, etc) on either the bottom of the tub, the side or both in case one fades.
Position the seeds evenly across surface using forceps or just sprinkle them. A max of say 50 – 100 seeds per tub. We then tamp down again lightly and spray evenly and lightly with seaweed solution.
You can use a fungicide or mycorrizal fungal powder to assist germination by dusting the seeds in it before planting. A good organic method is to use ground cinnamon, sprinkle it over the surface and mix it in before sowing the seeds. We are currently experimenting with inoculated biochar as part of the seed mix, it appears to be working very well.
Close the lid and place in a bright spot well away from direct sun, if there is any danger of direct sun at anytime cut a piece of 50-75% shadecloth and drape it over the tub. You may need to double it up initially, if the seedlings go red, you need more shade. We find that they really need minimal light when germinating and in the first few months.
Germination starts in 2-3 weeks, spring and autumn being good times for Trichocereus with moderate temperatures.
Ignore other teks that tell you to open the lids once germination occurs, not in this tek, dryness at such a tender stage is either lethal or severely stunting. Leave the lids sealed for up to 6 months, it acts like a mini terrarium, recycling moisture. After 6 months it’ll need a drink, but then you can reseal up to the 12 month mark by which time they should be ready to separate out and pot on. Ours are ready for the big world after 3-6 months.
Only open if you see fungus starting, in which case cracking the lid a while so excess moisture is lost can arrest the fungus.
If its too dry, in which case re-wet with a 1/8 strength solution of miracle gro or seaweed.
The cacti are ready to move on once they have a proper set of spines and a little girth. I find small cacti grow better communally, only being divided to their own pots once about 10 – 20mm tall. But that another stage and is outside the Takeaway Tek
This tek is a rather stress free way of going about growing from seed. R. Saw. author and heavily modified by us 🙂