Repotting guide

When & how to repot Brunnera macrophylla 'Looking Glass' (Brunnera macrophylla 'Looking Glass')

Also called Looking Glass brunnera.

More about brunnera macrophylla 'looking glass'

About Brunnera macrophylla 'Looking Glass'

Brunnera macrophylla 'Looking Glass' · also called Looking Glass brunnera · flowering

A dazzling sport of 'Jack Frost' with almost entirely silver, metallic heart-shaped leaves showing only faint green veining. Sprays of sky-blue forget-me-not flowers rise above the shimmering foliage in spring. This clump-forming shade perennial brightens dark woodland corners like a mirror, but its near-white leaves are more prone to sun scorch than greener types.

Mature size: 30-40 cm tall and 45-60 cm wide (about 12-16 in tall, 18-24 in wide)

How to tell brunnera macrophylla 'looking glass' needs repotting

Repotting on a calendar is less reliable than reading the plant. For brunnera macrophylla 'looking glass', 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 brunnera macrophylla 'looking glass') 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 brunnera macrophylla 'looking glass'

Only every 2–4 years, when genuinely crowded. Brunnera macrophylla 'Looking Glass' 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. Clump-forming, slowly spreading herbaceous perennial forming mounds of near-silver heart-shaped foliage, with airy blue flower sprays in spring. Foliage holds through the season..

What size pot to step brunnera macrophylla 'looking glass' up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Brunnera macrophylla 'Looking Glass' 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 brunnera macrophylla 'looking glass' 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 brunnera macrophylla 'looking glass'

Early spring, just as new growth restarts, is the ideal window for brunnera macrophylla 'looking glass'. 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 brunnera macrophylla 'looking glass'

Confirm it actually needs it. Slide brunnera macrophylla 'looking glass' 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 brunnera macrophylla 'looking glass' 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 moist, well-drained, humus-rich 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 brunnera macrophylla 'looking glass' 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 brunnera macrophylla 'looking glass'

Brunnera macrophylla 'Looking Glass' wants moist, well-drained, humus-rich soil. Fertile, organically rich, evenly moist but free-draining soil. Tolerant of varied pH. Amend with leaf mould or compost; avoid dry or compacted sites that trigger leaf scorch. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting brunnera macrophylla 'looking glass' — frequently asked questions

How often should you repot brunnera macrophylla 'looking glass'?

Only every 2–4 years, when genuinely crowded for brunnera macrophylla 'looking glass'. Only repot brunnera macrophylla 'looking glass' 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 moist, well-drained, humus-rich soil. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does brunnera macrophylla 'looking glass' need?

When is the best time of year to repot brunnera macrophylla 'looking glass'?

Does brunnera macrophylla 'looking glass' like to be root-bound?

Yes — brunnera macrophylla 'looking glass' 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 brunnera macrophylla 'looking glass' after repotting?

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