Mature size & growth rate

How big does Mountain Rimu (Dacrydium bidwillii) get?

Also called Bog Pine, Mountain Pine, New Zealand Mountain Rimu.

More about mountain rimu

About Mountain Rimu

Dacrydium bidwillii · also called Bog Pine, Mountain Pine · flowering

Mountain Rimu is a compact, slow-growing podocarp conifer native to the montane and subalpine zones of New Zealand's North and South Islands. It forms a low, spreading shrub with fine, scale-like leaves. Hardy and moisture-tolerant, it suits cool temperate gardens and rock gardens. It is not on the ASPCA toxic plants list.

Mature size: 0.3-1.5 m tall, spreading to 1-2 m wide

Watch for — Poor growth in alkaline soil: Chlorosis and slow growth indicate high pH. Amend soil with sulphur or use ericaceous compost.

Indoor size vs how big it gets in the wild

Mountain Rimu 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 0.3-1.5 m tall, spreading to 1-2 m wide. 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

Mountain Rimu is a slow grower. Realistically, expect a decade or more — slow growers like this add only a few centimetres a year, so expect 8-15+ years to reach their indoor ceiling. Its feeding profile backs this up: apply a slow-release ericaceous fertiliser in early spring. ericaceous (acid-forming) feeds help maintain soil acidity. avoid over-fertilising as this podocarp is adapted to low-nutrient conditions.

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

How to keep mountain rimu smaller

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

The decisive tool is the secateurs: mountain rimu 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.
Good news: slow growth means topping it once buys you years before it needs doing again.

The keep-it-smaller method, step by step

Pick the new height. Decide how tall you want mountain rimu 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 mountain rimu bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for mountain rimu 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 mountain rimu light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When mountain rimu outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for mountain rimu:

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 mountain rimu repotting guide. If you want more of this plant instead of a bigger one, the mountain rimu propagation guide turns prunings into new plants.

Mountain Rimu size — frequently asked questions

How big does mountain rimu get?

Mountain Rimu reaches 0.3-1.5 m tall, spreading to 1-2 m wide 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 mountain rimu slow or fast growing?

Mountain Rimu is a slow grower. Expect a decade or more — slow growers like this add only a few centimetres a year, so expect 8-15+ years to reach their indoor ceiling. Mountain Rimu grows on a tree's timeline and scale — indoors it becomes a tall, trunked statement plant rather than a tabletop one.

How long does mountain rimu take to reach full size?

Roughly a decade or more — slow growers like this add only a few centimetres a year, so expect 8-15+ years to reach their indoor ceiling. Light, pot size and feeding move that timeline more than anything else.

How do I keep mountain rimu smaller?

The decisive tool is the secateurs: mountain rimu 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. Good news: slow growth means topping it once buys you years before it needs doing again.

How can I make mountain rimu 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.