Re-rooting a Sunburned, Top-Heavy Mexican Fencepost Cactus

A 4-foot Mexican fencepost (Pachycereus marginatus) has a sunburned, weakened lower half and a healthy top. It's top-heavy and unstable. Solution: cut above the sunburn with a sterilized knife, let the cutting callous 2+ weeks until corky, plant in deep pot with moistened builders sand (not play sand), just deep enough to stand. Water only when sand is bone-dry. Rooting takes weeks to months—new growth at the tip confirms success. Then transplant to cactus soil.

The remaining base, if the weak portion is removed, may sprout new arms in a smaller pot. Denver's climate suits this summer project.