Mature size & growth rate

How big does Forget-me-not (Myosotis sylvatica) get?

Also called wood forget-me-not, garden forget-me-not.

About Forget-me-not

Myosotis sylvatica · also called wood forget-me-not, garden forget-me-not · flowering

Forget-me-nots are biennial woodland edge plants with clouds of sky-blue (and rare pink/white) tiny flowers in spring. Self-seed prolifically — almost too well. Pet-safe and a popular underplanting for tulips and bulbs.

Garden forget-me-not (Myosotis sylvatica) is a tufted, hairy short-lived perennial native to woodland and rocky places, including the British Isles, almost always grown as a biennial for spring color.

Self-seeds freely and sometimes aggressively, persisting in the garden for years; in formal beds plants are pulled after flowering to control spread.

Mature size: 20-30 cm tall

Sources: rhs.org.uk, missouribotanicalgarden.org

Indoor size vs how big it gets in the wild

Forget-me-not 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 20-30 cm tall. 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

Forget-me-not is a moderate grower. Realistically, expect a single growing season — it reaches full size in one year, then is done. Its feeding profile backs this up: compost top-dress at planting.

Want this turned into the right next pot at the right moment? The pot size calculator and the forget-me-not repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast forget-me-not grows.

How to keep forget-me-not smaller

You are not stuck with the maximum size. For forget-me-not specifically, these are the levers, in order of impact:

Choose a compact or dwarf variety of forget-me-not 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 forget-me-not bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for forget-me-not 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 forget-me-not light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When forget-me-not outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for forget-me-not:

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 forget-me-not repotting guide. If you want more of this plant instead of a bigger one, the forget-me-not propagation guide turns prunings into new plants.

Forget-me-not size — frequently asked questions

How big does forget-me-not get?

Forget-me-not reaches 20-30 cm tall 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 forget-me-not slow or fast growing?

Forget-me-not is a moderate grower. Expect a single growing season — it reaches full size in one year, then is done. Forget-me-not 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 forget-me-not 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 forget-me-not smaller?

Choose a compact or dwarf variety of forget-me-not 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 forget-me-not 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.