Mature size & growth rate

How big does African Blue Basil (Ocimum kilimandscharicum × basilicum 'Dark Opal') get?

Also called Perennial Basil.

More about african blue basil

About African Blue Basil

Ocimum kilimandscharicum × basilicum 'Dark Opal' · also called Perennial Basil · herb

African Blue basil is a sterile interspecific hybrid that is unusually long-lived and vigorous, with camphor-scented purple-veined leaves and near-constant lavender flower spikes that are magnets for bees. Because it sets no seed it never truly bolts, so it stays productive for months. Tender to frost, it is often overwintered indoors as a perennial.

Mature size: 60-120 cm tall and 60-90 cm wide in a long warm season

Watch for — Sprawling, woody growth: Large plants flop and go woody at the base. Pinch hard and prune regularly to keep a dense, leafy shape.

Indoor size vs how big it gets in the wild

African Blue Basil reaches its full size within one growing season — there is no "long-term" size, just how big it gets before you harvest or it dies back. Indoors and in a pot, expect 60-120 cm tall and 60-90 cm wide in a long warm season. A pot, your light levels and a little pruning are what set the final size in a home, far more than the plant's theoretical potential.

It sizes up fast and once, racing from seedling to full size in a single season; after cropping it is finished, so size is a within-season question.

Growth rate and years to mature

African Blue Basil is a fast grower. Realistically, expect a single growing season — it reaches full size in one year, then is done. Its feeding profile backs this up: feed every 3-4 weeks with a balanced liquid fertiliser at half strength through the growing season. as a long-lived, large plant it appreciates steadier feeding than annual basils, especially in containers.

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

How to keep african blue basil smaller

You are not stuck with the maximum size. For african blue basil specifically, these are the levers, in order of impact:

Choose a compact or dwarf variety of african blue basil from the start — that is the most reliable size control for an annual.
Grow it in a smaller container to naturally limit how large it gets.
For some crops, pinching or pruning the growing tips keeps the plant shorter and bushier.
Sow a little later or space plants closer if you specifically want smaller individual plants.

How to grow african blue basil bigger or faster

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

Full sun, warm soil and steady water are what drive a crop to full size fastest.
Sow at the right time for your zone so it gets the whole season to size up.
Feed appropriately for the crop and never let it check (stall) from drought or cold.

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

When african blue basil outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for african blue basil:

It sprawls beyond its bed or container before harvest — usually a spacing or support issue.
It flops or needs staking once it hits full height.
Once it has fruited or bolted, it is at its final size for good — the next plant is a new sowing.

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

African Blue Basil size — frequently asked questions

How big does african blue basil get?

African Blue Basil reaches 60-120 cm tall and 60-90 cm wide in a long warm season when grown indoors. It sizes up fast and once, racing from seedling to full size in a single season; after cropping it is finished, so size is a within-season question.

Is african blue basil slow or fast growing?

African Blue Basil is a fast grower. Expect a single growing season — it reaches full size in one year, then is done. African Blue Basil reaches its full size within one growing season — there is no "long-term" size, just how big it gets before you harvest or it dies back.

How long does african blue basil take to reach full size?

Roughly a single growing season — it reaches full size in one year, then is done. Light, pot size and feeding move that timeline more than anything else.

How do I keep african blue basil smaller?

Choose a compact or dwarf variety of african blue basil from the start — that is the most reliable size control for an annual. Grow it in a smaller container to naturally limit how large it gets. For some crops, pinching or pruning the growing tips keeps the plant shorter and bushier. Sow a little later or space plants closer if you specifically want smaller individual plants.

How can I make african blue basil grow bigger or faster?

Full sun, warm soil and steady water are what drive a crop to full size fastest. Sow at the right time for your zone so it gets the whole season to size up. Feed appropriately for the crop and never let it check (stall) from drought or cold.