CactiGuide.com

My neighbour has a large cereus in his yard, around 4m tall with lots of branches and probably 50 years old. I'm going to take a 1 metre cutting (with his permission) and plant it in the same position in my yard, under the eaves where it's fairly dry.

I'm wondering if I should take it now and let it heal over winter, or wait until spring before cutting? July temperatures here average 12C/0C (high/low), and it very occasionally gets to -3C overnight. If I store it over winter would the dark cold garage be better, or outside?

Another question, should I apply sulphur or something to the cut on my neighbour's donor plant or let it heal naturally?

You could apply Sulphur or root hormone powder (what I use). Let the cut heal to calloused over before planting. Were it me, I would probably do it indoors and after the cut heals place it vertical in a pot with sand making contact with the callous for a month or so. Then check for roots. Wait again if not then check again.
Some experts should chime in soon enough with better advice than mine hopefully.
Kia kaha!

Thanks, sand is a great idea for rooting. I have the cut currently healing in a cool room, and as you say I'll keep it inside until spring.

I think I'll also use sand to root some offsets from another cactus I have (mammillaria I think), then pot them once I see roots.