Tom wrote:

I'm sure I've got some that lean away from the sun... but others appear
to lean into it.

Is there an answer to this?

To be honest, it's a bit of a problem with my large cacti as I need them
to grow straight up - there's very little room here.

Cheers for any help,

Tom.

Here's a thought...

Some cacti swell up when it rains, so perhaps, if they only found
water on one side, they'd swell up on that side and lean away.
Are you watering them unevenly?

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Sleepalot aa #1385