Mature size & growth rate

How big does Simon Bamboo (Pleioblastus simonii) get?

Also called Simon Bamboo, Medake.

More about simon bamboo

About Simon Bamboo

Pleioblastus simonii · also called Simon Bamboo, Medake · tropical

Pleioblastus simonii (Medake) is a tall, vigorous running bamboo native to Japan reaching 3–6 m in warm climates. It forms dense thickets with slender culms and lance-shaped mid-green leaves. Hardy to USDA zone 6, it works well as a privacy screen or windbreak. Running rhizomes require containment; cut back crowded clumps every few years to rejuvenate.

Mature size: 3–6 m tall (temperate UK/US), spreading via running rhizomes

Watch for — Rhizome spreading out of control: Simon Bamboo is a vigorous runner that can spread many metres per year in warm conditions. Install heavy-duty HDPE rhizome barriers at least 70 cm deep before planting. Monitor edges annually and sever escapees with a spade.

Indoor size vs how big it gets in the wild

Simon Bamboo grows on a tree's timeline and scale — indoors it becomes a tall, trunked statement plant rather than a tabletop one. Indoors and in a pot, expect 3–6 m tall (temperate uk/us), spreading via running rhizomes. 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 gains real height on a trunk or main stem, adding a tier of leaves a year and eventually reaching for the ceiling — this is a plant you grow up, not out.

Growth rate and years to mature

Simon Bamboo is a fast grower. Realistically, expect two to four years from a young plant to a room-filling specimen in good light. Its feeding profile backs this up: apply a high-nitrogen granular fertiliser (e.g. 20-10-10) in spring as new shoots push. feed again with a balanced fertiliser in midsummer. avoid autumn feeding which stimulates tender late growth vulnerable to frost damage.

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

How to keep simon bamboo smaller

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

The decisive tool is the secateurs: simon bamboo can be topped (cut the main growing tip) to cap its height and force a bushier, shorter shape.
Keeping it deliberately pot-bound in a snug container slows the whole plant and limits ultimate size.
Prune in spring so it heals fast; remove the tallest leader back to a node to reset the height.
Expect to top or hard-prune it every year or two — left alone it heads for the ceiling.

The keep-it-smaller method, step by step

Pick the new height. Decide how tall you want simon bamboo and find a leaf node or branch point just below that.
Top the main stem. Cut the main growing tip cleanly just above that node in spring; this permanently caps the height and forces side branches.
Keep the pot snug. Avoid jumping to a much bigger pot — a slightly restricted rootball keeps the whole plant smaller.
Maintain the shape. Prune back the tallest new leaders each spring to hold it at the height you chose.

How to grow simon bamboo bigger or faster

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

It already wants the bright light it needs; warmth, a yearly pot-up and spring-summer feed are the accelerators.
Pot up a size every year or two while young; restricted roots are the main thing holding height back.
Feed regularly through the growing season and keep it warm — height comes from sustained good conditions.

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

When simon bamboo outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for simon bamboo:

The top leaves pressing against or bent by the ceiling — the classic "this is now too tall indoors" sign.
It has to be moved away from a light source it has literally outgrown.
Roots filling the largest pot you can reasonably keep indoors — at that point it is top-or-prune or move it outside (if hardy).

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

Simon Bamboo size — frequently asked questions

How big does simon bamboo get?

Simon Bamboo reaches 3–6 m tall (temperate uk/us), spreading via running rhizomes when grown indoors. It gains real height on a trunk or main stem, adding a tier of leaves a year and eventually reaching for the ceiling — this is a plant you grow up, not out.

Is simon bamboo slow or fast growing?

Simon Bamboo is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. Simon Bamboo grows on a tree's timeline and scale — indoors it becomes a tall, trunked statement plant rather than a tabletop one.

How long does simon bamboo take to reach full size?

Roughly two to four years from a young plant to a room-filling specimen in good light. Light, pot size and feeding move that timeline more than anything else.

How do I keep simon bamboo smaller?

The decisive tool is the secateurs: simon bamboo can be topped (cut the main growing tip) to cap its height and force a bushier, shorter shape. Keeping it deliberately pot-bound in a snug container slows the whole plant and limits ultimate size. Prune in spring so it heals fast; remove the tallest leader back to a node to reset the height. Expect to top or hard-prune it every year or two — left alone it heads for the ceiling.

How can I make simon bamboo grow bigger or faster?

It already wants the bright light it needs; warmth, a yearly pot-up and spring-summer feed are the accelerators. Pot up a size every year or two while young; restricted roots are the main thing holding height back. Feed regularly through the growing season and keep it warm — height comes from sustained good conditions.