Repotting guide

When & how to repot Quaking Grass (Briza media)

Also called quaking grass, trembling grass, doddering dillies.

More about quaking grass

About Quaking Grass

Briza media · also called quaking grass, trembling grass · flowering

Quaking grass is a dainty, cool-season perennial grass famous for its heart-shaped, locket-like flower spikelets that dangle on hair-fine stems and tremble with the slightest breeze. Forming low tufts of blue-green foliage, it suits wildflower meadows, gravel gardens and naturalistic borders. The papery, shimmering seedheads dry beautifully and are prized for cut and dried arrangements.

Mature size: Foliage tuft 15-30 cm tall; airy flowering stems reach 45-75 cm (about 1.5-2.5 ft) tall and 30 cm wide.

How to tell quaking grass needs repotting

Repotting on a calendar is less reliable than reading the plant. For quaking 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 quaking 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 quaking grass

Only every 2–4 years, when genuinely crowded. Quaking 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. Low, tufted, semi-evergreen clump of fine blue-green foliage sending up slender, wiry stems hung with delicate, nodding, locket-shaped flower spikelets that quake in the breeze..

What size pot to step quaking grass up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Quaking 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 quaking 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 quaking grass

Early spring, just as new growth restarts, is the ideal window for quaking 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 quaking grass

Confirm it actually needs it. Slide quaking 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 quaking 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 well-drained, lean to average soil, 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 quaking 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 quaking grass

Quaking Grass wants well-drained, lean to average soil. Thrives in poor to moderately fertile, free-draining soils and is notably happy on chalky, alkaline ground; tolerates neutral to alkaline pH. Avoid rich, wet soils that cause floppy growth. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting quaking grass — frequently asked questions

How often should you repot quaking grass?

Only every 2–4 years, when genuinely crowded for quaking grass. Only repot quaking 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 well-drained, lean to average soil. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does quaking grass need?

When is the best time of year to repot quaking grass?

Does quaking grass like to be root-bound?

Yes — quaking 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 quaking grass after repotting?

Not immediately. Wait about 4 weeks after repotting quaking 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.