Beheading old timers

[Mike]

I'd appreciated fellow forumites experience and advice on beheading old timers...
By which I mean old plants the top half of which looks lovely, but the bottom half of which is badly marked, or generally looking tired and unattractive. Up to now I've been burying part of the nasty lower parts in a deep layer of gravel at the top of their pot. But that's now getting impractical without using pots that are so deep and/or wide that they look wrong (and take up too much space!).
I'm tempted to take the knife to two in particular, a 35-year-old Astrophytum capricorne, and a 25(?) year old Parodia microsperma. If I do, when's the best time to do this - when they're in active growth or now while they're dormant?
Cheers for any advice.
Mike

[Martin]

Chopping them now and letting they dry for 4 to 6 wks then rooting as spring starts is a good way to do this

Not sure how easy to re root the Astrosphytum will be but the parodia should be ok

M

[lobman]

I would not fancy rooting the parodia , as the core will probably be quite soft -- I would either cut it higher up and wait for the offsetts to form on the lower half , and then cut them off and re root when a fair size , eg golf ball , or learn to like it as it is !

[EuphorbianDM77]

When I have an old plant after many years of growing, I personally wouldn't cut it.

[Mike]

Part of the problem with the Parodia is the way (like. P. leninghausii) it loses turgor pressure in winter, shrinks and leans over, now needing to be supported to avoid falling out of its pot. And that's hard to do without damaging the spines. I'll certainly keep the base to 'harvest' and new shoots in case the top fails to root. I'd hate to lose it as it's such a good bloomer. Here it is back in 2010.
Mike

[Peter]

I've done this three times with Astros. Lost two, but the one that did root successfully has been transformed from an ancient, woody, rather twisted plant to something that I'm rather chuffed with. It was chopped, dried and left in cat litter for the best part of a year before it decided to put out some roots.

[Tina]

Hi
What I often do with my plants -succulents mostly is cut half the area & wedge open with a plant label, maybe add some hormone rooting powder to the cut & leave for a couple/several months, then do maybe another quarter wait more month's so when I do the final cut there is only a small area to callous or risk with infection, the plants often know there is a problem & will start to form root nodules. I just think it's a safer way to do this if you have the time.

A friend used to recommend giving high nitrogen feeds to promote offsetting at this stage but I'm not certain of the science I suppose it would make sense to give the base a good feed to get it growing/offsetting.