Mature size & growth rate

How big does Lobster Flower (Plectranthus neochilus) get?

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.

Indoor size vs how big it gets in the wild

Lobster Flower stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward. Indoors and in a pot, expect 20–30 cm (8–12 in) tall with a spread of up to 90 cm (3 ft) in open ground. In the ground with no restriction it is a completely different plant — more upright in containers. — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Growth rate and years to mature

Lobster Flower is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: apply a balanced liquid fertiliser at half-strength once monthly during spring and summer; excessive nitrogen encourages lush, floppy growth at the expense of flowers.

Want this turned into the right next pot at the right moment? The pot size calculator and the lobster flower repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast lobster flower grows.

How to keep lobster flower smaller

You are not stuck with the maximum size. For lobster flower specifically, these are the levers, in order of impact:

Divide the clump every year or two — splitting lobster flower is the main way to control its spread and refresh it.
Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump.
Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

The keep-it-smaller method, step by step

Lift the whole plant. Slide lobster flower out of its pot in spring when the clump has filled it.
Split the clump. Tease or cut the rootball into two or more sections, each with healthy roots and growth.
Repot one division. Put a single division back in the original pot to reset it to a smaller size; pot or give away the rest.
Remove offsets as they form. Through the year, detach new runners or pups to stop it spreading again.

How to grow lobster flower bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for lobster flower the accelerators are:

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger.
Good light plus regular feeding maximises offset and runner production.
Leave plantlets and offsets attached and feed through the growing season for the fastest spread.

Light is almost always the ceiling. The lobster flower light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When lobster flower outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for lobster flower:

The clump bulging over the pot rim or splitting the pot — the cue to divide, not to find a bigger room.
A dense centre that goes bare or tired while the edges keep spreading.
Runners or offsets escaping across the shelf or into neighbouring pots.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the lobster flower repotting guide. If you want more of this plant instead of a bigger one, the lobster flower propagation guide turns prunings into new plants.

Lobster Flower size — frequently asked questions

How big does lobster flower get?

Lobster Flower reaches 20–30 cm (8–12 in) tall with a spread of up to 90 cm (3 ft) in open ground when grown indoors, and far larger where it grows unrestricted (more upright in containers.). Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Is lobster flower slow or fast growing?

Lobster Flower is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Lobster Flower stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward.

How long does lobster flower take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep lobster flower smaller?

Divide the clump every year or two — splitting lobster flower is the main way to control its spread and refresh it. Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump. Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

How can I make lobster flower grow bigger or faster?

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger. Good light plus regular feeding maximises offset and runner production. Leave plantlets and offsets attached and feed through the growing season for the fastest spread.