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[tetris]

I have a cactus that has been in a solo cup for a few years and seems to want a new pot to be planted in.  The dirt I used when I first planted it was garbage (full of peat moss and coco coir... sort of like it was meant for growing pot)

I was wondering if people would tend to try removing the old dirt, or simply add new/better dirt while re-potting.  I'm also interested in hearing about if people think trimming the roots would be a good idea. 

Thanks for your input!

[geezer]

I've washed several roots over the years. There doesn't seem to be any bad consequence to it although it seems likely that some micro root might be removed in the process which is where the real interacting with the soil happens.

Root washing is usually done to remove some pathogen or bug. Simply changing the soil seems to be the right way to go for your transplant especially since you've not suggested a problem at or with the root.

[geezer]

Your next soil should have much more mineral in it with a small percentage, let's say less than 15%, of fully composted compost. Your grafting stock will thrive with a lot of water as long as the soil will drain quickly, which makes fertilizing with a dilute fertilizer easy as can be.

You must be being careful with the watering as there's no indication of rot in the pot. Overwatering that soil mix would most likely rot the roots pdq but your grafting stock and scion look very good. I wish I had one

[tetris]

Thanks for the help, geezer.  It took quite a bit of time to nurse the scion back to health, as it did start rotting shortly after the graft started.  Now it has a cool scar. 

My next question is, how deep should the soil be?  Should I keep roughly the same depth, go more shallow or go deeper?

[geezer]

I don't graft so I honestly don't have valuable input on that matter.

BUT

......assuming the scion grows best on root stock that's growing vigorously....

you'd want to bulk up the root stock and that's done by growing a big root ball

so I'd guess the right way to go is a pot about 10 inches tall and 6 inches across. There's plenty of room for root growth there and I'd think with summer heat and light but not too much moisture you'd grow a healthy root system pdq. When you don't water the trichs they get nervous and start seeking water by way of new roots. You don't want to wilt it but don't want to give it any more water than it needs to stay healthy but hungry. It's a thing you learn with experience but thankfully have to work pretty hard to screw up.

anyway, better that someone who grafts long term chime in on this

[geezer]

Inyan and Boebs might be members here.

both are big time grafters

Boebs is active at Mycotopia these days

[tetris]

Well, i mixed some new dirt today and found a 10x6 pot.  I went with a perlite topper, to reflect more light back to the scion. 

I'll try out mycotopia, thanks for the advice.  I'm wondering if they have a more active forum over there?  I'm not seeing all too much action in this place, though I haven't made to the next level of membership, so there are still hidden parts here. 

Anyhow, this is what my baby is looking like now,

[geezer]

see if you can find a pdf titled The Stone Eaters

very useful info toward understanding the biology of the interaction between cactus roots and basically rocky soil. it will likely change the way you go about making soil mixes in the future.

it used to be everywhere on the net but seems to have been memory holed

1 Like Hopfrog likes this.

[tetris]

I read "The Stone Eaters" and will agree it is a great book for cactus growers to look into.  I've replanted about 10 cacti thus far, and am excited to see how things go.

1 Like Hopfrog likes this.