Repotting guide

When & how to repot Notch Cactus (Obregonia denegrii)

Also called Artichoke Cactus, Peyotillo, Notch Cactus.

More about notch cactus

About Notch Cactus

Obregonia denegrii · also called Artichoke Cactus, Peyotillo · houseplant

Notch cactus is a rare, slow-growing Mexican monotype whose overlapping triangular tubercles spiral out like an artichoke or green dahlia, each tipped with a soft tuft of weak spines. A swollen tap root anchors the flattened rosette, which crowns itself with white-to-pink flowers. Endangered in the wild, it is a prized, undemanding collector's cactus.

Mature size: Reaches about 10-12 cm across and only a few centimetres tall, very slowly over many years.

Watch for — Tap-root rot: The swollen root rots fast if overwatered or grown in retentive soil, often with no warning until the body softens. Water sparingly in very gritty mix and keep dry in winter.

How to tell notch cactus needs repotting

Repotting on a calendar is less reliable than reading the plant. For notch cactus, watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot notch cactus

Every 2–3 years, into bone-dry mix. Notch Cactus's growth habit — slow-growing solitary cactus forming a flattened, artichoke-like rosette of spiralling triangular tubercles over a stout tap root; rarely offsets. — sets the pace. Notch cactus is a rare, slow-growing Mexican monotype whose overlapping triangular tubercles spiral out like an artichoke or green dahlia, each tipped with a soft tuft of weak spines. A swollen tap root anchors the flattened rosette, which crowns itself with white-to-pink flowers. Endangered in the wild, it is a prized, undemanding collector's cactus.

What size pot to step notch cactus up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Notch Cactus stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot notch cactus

Spring or summer, while notch cactus is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting notch cactus

Repot dry. Do not water notch cactus for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty very gritty, fast-draining mineral mix ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set notch cactus at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep notch cactus completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for notch cactus

Notch Cactus wants very gritty, fast-draining mineral mix. An extra-sharp blend heavy on pumice, grit and perlite with only a little organic matter, to protect the rot-prone tap root. A deep pot accommodates the long root. Drainage cannot be too good for this species. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting notch cactus — frequently asked questions

How often should you repot notch cactus?

Every 2–3 years, into bone-dry mix for notch cactus. Repot notch cactus every 2–3 years into a snug pot of very gritty, fast-draining mineral mix, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does notch cactus need?

When is the best time of year to repot notch cactus?

Should you water notch cactus after repotting?

No — not straight away. Repot notch cactus into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise notch cactus after repotting?

Not immediately. Wait about 3 weeks after repotting notch cactus. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.