Pilosocereus Azureus aka the Blue Torch Cactus is one of my favourites. They are fairly hardy in Melbourne’s climate and are quite an attractive, Blue Cactus. They’re also readily available in retail nurseries that carry cactus around Australia (and probably elsewhere worldwide) and usually seed grown, so you will find some variation in appearance, hardiness and growth rate.
So to continue on from my article about buying seed grown cacti, buying the Blue Torch Cactus is a good example or what I was writing about.
Over the last few years I’ve purchased a few of these to grow out. Some were planted in the ground, while others were potted up into larger pots. Most of these were in 55mm punnets, so they were quite small. Unfortunately, mostly were fairly slow to grow, except for this one.
You can see from the growth rings it’s showing about 4 years of growth. It’s now about 70cm tall and put on around 20cm of growth last season. Not really a fast grower, but then this position only gets about half a days sunlight over the warmer months, max! So it’s not really in it’s best position.
Then in May 2021 I came across these 2 Pilosocereus Azureus, below.
When I came across them they were in 80mm punnets and were much larger than the previous Pilosocereus Azureus I’d purchased. Over the next growing season they started to grow quite nicely and looked quite healthy in their larger pots. It was then that I first started to develop my theory.
At first I assumed, because they were larger, they were a year older and hence more likely to grow faster, now outside of the greenhouse. But that didn’t seem to mirror what I was seeing. Most of the smaller one’s I’d purchased, were still very slow to grow. Even after 1 or 2 years!
Then it dawned on me what the situation really was. These larger plants likely weren’t older than the smaller ones. It’s my guess that they were the superior ones (faster growing ones) from the same batch of seed. They grew faster earlier and got potted into larger pots, which in turn helped them to grow faster again. I’ve also experienced this with several other types of cacti originating from this wholesale nursery as well.
So if you want a faster growing cactus, then ones in the 80mm punnets do seem to grow a lot faster than the ones in the 55mm punnets. Not because they are bigger, but probably because they are better!
So here are the same 2 Pilosocereus Azureus after getting potted up again.
From the photos you might notice another difference as well. The 2 Pilosocereus Azureus do look slightly different. Another common trait of seed grown cacti. You can get variations in appearance as well. The one on the right has nice yellow splines which contrast nicely against the blue. While the spines on the left are much duller. However, the blue on the one on the left does appear much deeper (maybe not as apparent in the photo?).
FOOTNOTE: You might notice how the potting mix has dropped into the pot over time. I use a 50/50 mix of general potting mix and perlite which can drop over time. Plus I’ve found worms can get it there as well and turn the mix into worm castings which tends to compact it also.
Also, I don’t really like to over-pot these type of cacti as it can lead to root rot. I have found that using a free-draining mix, drilling extra drainage holes in the bottom, adding a soil probiotic and using porous clay pots can remove excess moisture and help keep the roots healthy.
In this case though, I think in spring I’ll remove them and plant them into the garden. They are quite hardy and will hopefully really accelerate their growth in a nice sunny, well drained position.
