Repotting guide

When & how to repot Hydrangea 'Endless Summer' (Hydrangea macrophylla 'Bailmer' (Endless Summer))

Also called Endless Summer hydrangea, reblooming hydrangea.

More about hydrangea 'endless summer'

About Hydrangea 'Endless Summer'

Hydrangea macrophylla 'Bailmer' (Endless Summer) · also called Endless Summer hydrangea, reblooming hydrangea · flowering

Endless Summer is a reblooming bigleaf hydrangea bred to flower on both old and new wood, so it keeps producing its rounded mophead blooms from early summer to frost even after a hard winter or spring pruning. Flowers swing blue in acidic soil and pink in alkaline soil, making it a versatile, long-blooming shrub for borders and containers.

Mature size: 0.9-1.5 m (3-5 ft) tall and wide, forming a compact, rounded shrub well suited to borders and large containers.

Watch for — Powdery mildew and leaf spot: Humid, crowded, poorly ventilated plantings develop fungal leaf disease. Improve airflow, water at the base rather than overhead, and remove fallen infected leaves.

How to tell hydrangea 'endless summer' needs repotting

Repotting on a calendar is less reliable than reading the plant. For hydrangea 'endless summer', 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 hydrangea 'endless summer') 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 hydrangea 'endless summer'

Only every 2–4 years, when genuinely crowded. Hydrangea 'Endless Summer' 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. Deciduous, rounded, mounding shrub that reblooms on both old and new wood. It produces flushes of large globe-shaped flower clusters over a long season above broad, coarsely toothed bright green leaves..

What size pot to step hydrangea 'endless summer' up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Hydrangea 'Endless Summer' 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 hydrangea 'endless summer' 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 hydrangea 'endless summer'

Early spring, just as new growth restarts, is the ideal window for hydrangea 'endless summer'. 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 hydrangea 'endless summer'

Confirm it actually needs it. Slide hydrangea 'endless summer' 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 hydrangea 'endless summer' 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 rich, moist, well-drained loam, 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 hydrangea 'endless summer' 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 hydrangea 'endless summer'

Hydrangea 'Endless Summer' wants rich, moist, well-drained loam. Wants fertile, humus-rich, moisture-retentive but well-drained soil. Soil pH controls flower colour: acidic (below ~6) gives blue, alkaline (above ~7) gives pink. Amend with sulphur or aluminium sulphate for blue, lime for pink. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting hydrangea 'endless summer' — frequently asked questions

How often should you repot hydrangea 'endless summer'?

Only every 2–4 years, when genuinely crowded for hydrangea 'endless summer'. Only repot hydrangea 'endless summer' 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 rich, moist, well-drained loam. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does hydrangea 'endless summer' need?

When is the best time of year to repot hydrangea 'endless summer'?

Does hydrangea 'endless summer' like to be root-bound?

Yes — hydrangea 'endless summer' 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 hydrangea 'endless summer' after repotting?

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