Repotting guide

When & how to repot Lobster Flower (Plectranthus neochilus)

Also called Lobster Flower, Blue Coleus, Spur Flower.

More about lobster flower

About Lobster Flower

Plectranthus neochilus · also called Lobster Flower, Blue Coleus · flowering

Plectranthus neochilus is a low-growing, mat-forming, semi-succulent perennial native to southern Africa, instantly recognisable by its lime-green, broad leaves with coppery-purple undersides and its strong, pungent aroma that is widely used as a natural cat and dog deterrent in gardens. It produces upright spikes of soft purple-blue tubular flowers through much of the growing season. The most important care fact is that it is remarkably drought tolerant due to its succulent stems, and overwatering is the primary cause of failure — water only when the soil is fully dry. Multiple sources classify the genus pattern as non-toxic to dogs and cats, and Mountain Crest Gardens specifically lists P. neochilus as pet-safe.

Mature size: 20–30 cm (8–12 in) tall with a spread of up to 90 cm (3 ft) in open ground; more upright in containers.

Watch for — Root and stem rot from overwatering: Soft, blackened stem bases and wilting despite moist soil indicate rot; cut away affected tissue, allow remaining roots to dry for 24 hours, and repot in fresh dry gritty mix.

How to tell lobster flower needs repotting

Repotting on a calendar is less reliable than reading the plant. For lobster flower, 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 lobster flower

Every 2–3 years, into bone-dry mix. Lobster Flower's growth habit — sprawling, mat-forming semi-succulent groundcover with upright flowering stems; spreads readily by stem layering. — sets the pace. Plectranthus neochilus is a low-growing, mat-forming, semi-succulent perennial native to southern Africa, instantly recognisable by its lime-green, broad leaves with coppery-purple undersides and its strong, pungent aroma that is widely used as a natural cat and dog deterrent in gardens. It produces upright spikes of soft purple-blue tubular flowers through much of the growing season. The most important care fact is that it is remarkably drought tolerant due to its succulent stems, and overwatering is the primary cause of failure — water only when the soil is fully dry. Multiple sources classify the genus pattern as non-toxic to dogs and cats, and Mountain Crest Gardens specifically lists P. neochilus as pet-safe.

What size pot to step lobster flower up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Lobster Flower 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 lobster flower

Spring or summer, while lobster flower 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 lobster flower

Repot dry. Do not water lobster flower 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 sandy, very well-draining succulent or cactus 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 lobster flower 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 lobster flower 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 lobster flower

Lobster Flower wants sandy, very well-draining succulent or cactus mix. Mix standard potting compost 50:50 with coarse sand, perlite, or pumice to achieve the sharp drainage this species demands; avoid peat-heavy or water-retentive mixes. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting lobster flower — frequently asked questions

How often should you repot lobster flower?

Every 2–3 years, into bone-dry mix for lobster flower. Repot lobster flower every 2–3 years into a snug pot of sandy, very well-draining succulent or cactus 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 lobster flower need?

When is the best time of year to repot lobster flower?

Should you water lobster flower after repotting?

No — not straight away. Repot lobster flower 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 lobster flower after repotting?

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