Repotting guide

When & how to repot Common Tussock Grass (Poa labillardieri)

Also called common tussock grass, tussock poa, tussock grass.

More about common tussock grass

About Common Tussock Grass

Poa labillardieri · also called common tussock grass, tussock poa · flowering

Common tussock grass is a large Australian native bunchgrass forming dramatic, arching mounds of fine, blue-grey to grey-green foliage. Tall, nodding flower panicles emerge in spring and early summer. Remarkably tough and adaptable, it tolerates drought, periodic flooding, poor soils, and coastal exposure. A key species in Australian ecological restoration and increasingly popular in naturalistic garden design.

Mature size: 60–90 cm tall (foliage); flower stems to 120 cm; tussocks 60–100 cm wide, expanding slowly with age

Watch for — Rust and leaf spot in humid conditions: Fungal leaf diseases may affect tussocks in very humid, poorly ventilated locations. Rarely life-threatening. Improve air circulation; remove and dispose of the worst affected leaves. Cut clumps back hard in late winter to remove accumulated diseased material.

How to tell common tussock grass needs repotting

Repotting on a calendar is less reliable than reading the plant. For common tussock grass, watch for these signs:

Roots spiralling thickly out of the drainage holes or pushing the whole plant up out of the pot.
The pot is so packed that water runs straight through in seconds and barely wets the soil.
It has split a plastic pot, or the rootball is a solid mass with almost no soil left when you slide it out.
Growth and (for common tussock grass) flowering have clearly stalled despite good light and feeding — but remember this plant likes being snug, so a little crowding alone is not a reason to repot.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot common tussock grass

Only every 2–4 years, when genuinely crowded. Common Tussock Grass is one of the plants that genuinely prefers a snug pot — it grows and flowers better with its roots a little restricted, so resist the urge to repot it on schedule. Large, dense, arching bunchgrass forming a rounded tussock mound of fine, blue-grey foliage; tall nodding panicles in spring.

What size pot to step common tussock grass up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Common Tussock Grass positively prefers a snug pot: it flowers and grows better when the roots are a little restricted. The single biggest repotting mistake here is over-potting — dropping common tussock grass into a pot two or three sizes up. All that surplus soil holds water the small root system cannot use, stays cold and wet, and rots the roots within weeks. When in doubt, choose the smaller pot.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot common tussock grass

Early spring, just as new growth restarts, is the ideal window for common tussock grass. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting common tussock grass

Confirm it actually needs it. Slide common tussock grass out and check the roots. Only continue if it is genuinely packed — this plant prefers a snug pot, so if there is still soil and room, put it straight back.
Pick a pot only one size up. Choose a pot just 2–3 cm wider with good drainage. Resist anything bigger; over-potting is the main killer here.
Ease it out gently. Water lightly the day before, then tip common tussock grass out, supporting the base. Tease the outer roots free only enough to stop them circling.
Repot at the same depth. Add a layer of fresh clay, loam, sand, or gravelly soils — highly adaptable, set the plant so the soil line sits exactly where it did before, and backfill around the sides, firming lightly.
Settle it in. Water once to settle the soil, then let it sit. Hold off on more water until the top of the soil dries — fresh soil around a small root system stays wet for a while.

Aftercare

Because the new soil holds more water than the old crammed rootball did, ease right back on watering — let the top of the soil dry before you water common tussock grass again, or you will rot the roots in the very pot you just moved it to. Keep it out of harsh direct sun for a fortnight. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for common tussock grass

Common Tussock Grass wants clay, loam, sand, or gravelly soils — highly adaptable. One of the most soil-adaptable Australian grasses, performing in heavy clay, sandy loam, and gravelly or rocky substrates. Tolerates poor, compacted, saline, and periodically waterlogged soils. pH tolerant from 5.0 to 8.0. Avoid permanently waterlogged anaerobic conditions. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting common tussock grass — frequently asked questions

How often should you repot common tussock grass?

Only every 2–4 years, when genuinely crowded for common tussock grass. Only repot common tussock grass every 2–4 years, and only when it is genuinely root-bound — it flowers and grows best slightly crowded. Step up just one pot size in spring using clay, loam, sand, or gravelly soils — highly adaptable. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does common tussock grass need?

When is the best time of year to repot common tussock grass?

Does common tussock grass like to be root-bound?

Yes — common tussock grass genuinely flowers and grows best when slightly pot-bound, so do not rush to repot it. The mistake to avoid is over-potting into a much larger pot: the excess soil stays wet, the roots cannot use it, and the plant rots. Only repot every few years and only one snug size up.

Should you fertilise common tussock grass after repotting?

Not immediately. Wait about 4 weeks after repotting common tussock grass. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.