Fertilising guide
How to fertilise Hydrangea 'Endless Summer' (Hydrangea macrophylla 'Endless Summer')— schedule & NPK
Also called Endless Summer Hydrangea, Reblooming Hydrangea.
More about hydrangea 'endless summer'
About Hydrangea 'Endless Summer'
Hydrangea macrophylla 'Endless Summer' · also called Endless Summer Hydrangea, Reblooming Hydrangea · flowering
Endless Summer is a reblooming bigleaf hydrangea that flowers on both old and new wood, giving mophead blooms from early summer to autumn. Flower colour shifts with soil pH: blue in acidic soil, pink in alkaline. A deciduous shrub for partial shade and moist, rich soil, it forgives spring frost damage by reblooming.
Growth habit: Rounded, deciduous, multi-stemmed shrub with bold leaves and large mophead flower clusters. Blooms on both old and new wood, so it reflowers even if old stems are frost-damaged.
Watch for — Few or no flowers: Usually too much shade, drought stress, or pruning at the wrong time. As a rebloomer it forgives some old-wood loss, but feed and water for best bloom.
What fertiliser hydrangea 'endless summer' actually wants — and why
Hydrangea 'Endless Summer' is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for hydrangea 'endless summer': match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed hydrangea 'endless summer', and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For hydrangea 'endless summer':
Feed in spring and again in early summer with a balanced slow-release fertiliser or one formulated for hydrangeas to sustain repeat flowering. For blue blooms, use an acidic/ericaceous feed. Avoid high-nitrogen feeds that grow leaves at the expense of flowers. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
The dormant-season rule matters more than the exact interval: skip feeding entirely when hydrangea 'endless summer' is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for hydrangea 'endless summer'
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for hydrangea 'endless summer'. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water hydrangea 'endless summer' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the hydrangea 'endless summer' watering schedule.
Signs you are over-feeding hydrangea 'endless summer'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for hydrangea 'endless summer':
- Brown, scorched leaf margins from too strong or too frequent a dose.
- White salt crust on the soil surface.
- Soft, lush growth that fruits or flowers poorly.
Signs you are under-feeding hydrangea 'endless summer'
- Yellowing leaves with green veins (iron chlorosis from high pH).
- Weak growth, poor cropping and an overall pale, stressed look.
- Stunted new shoots in spring despite adequate water and light.
If the symptoms point at watering, light or roots rather than nutrition, the full hydrangea 'endless summer' care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush hydrangea 'endless summer' with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Organic vs synthetic feeds for hydrangea 'endless summer'
Organic options
Composted pine bark, pine-needle mulch, used coffee grounds and an organic ericaceous feed gently maintain acidity. UK: Vitax or Westland Ericaceous; US: Espoma Holly-tone or Dr. Earth Acid Lovers. Slow, soil-improving, hard to overdo.
Synthetic / liquid feeds
A liquid or granular ericaceous feed — UK: Miracle-Gro Ericaceous, Vitax or Westland; US: Miracle-Gro Acid-Loving Plant Food or Espoma Holly-tone. Pair with rainwater and an acidic mulch for it to work.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising hydrangea 'endless summer' — frequently asked questions
What fertiliser does hydrangea 'endless summer' need?
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves. Hydrangea 'Endless Summer' is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
How often should I feed hydrangea 'endless summer'?
Feed in spring and again in early summer with a balanced slow-release fertiliser or one formulated for hydrangeas to sustain repeat flowering. For blue blooms, use an acidic/ericaceous feed. Avoid high-nitrogen feeds that grow leaves at the expense of flowers. Feed in spring and again in early summer with a balanced slow-release fertiliser or one formulated for hydrangeas to sustain repeat flowering. For blue blooms, use an acidic/ericaceous feed. Avoid high-nitrogen feeds that grow leaves at the expense of flowers. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
What strength of feed for hydrangea 'endless summer'?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for hydrangea 'endless summer'. The variable that actually matters is pH, not concentration.
What does over-feeding hydrangea 'endless summer' look like?
Brown, scorched leaf margins from too strong or too frequent a dose. White salt crust on the soil surface. Soft, lush growth that fruits or flowers poorly. Feeding hydrangea 'endless summer' an ordinary fertiliser, or growing it in hard tap water / limey soil, is the defining mistake — it triggers lime-induced chlorosis (yellow leaves, green veins) no amount of feeding fixes until the pH comes down.
Should I flush the soil of hydrangea 'endless summer'?
Flush hydrangea 'endless summer' with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Keep reading
- Hydrangea 'Endless Summer' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water hydrangea 'endless summer' — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
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- All 1284 fertilising guides in the Growli library