Soil & potting mix

Best soil for Nikko Blue Bigleaf Hydrangea (Hydrangea macrophylla 'Nikko Blue')

Also called Nikko Blue Hydrangea, Bigleaf Hydrangea, Mophead Hydrangea.

More about nikko blue bigleaf hydrangea

Nikko Blue Bigleaf Hydrangea soil at a glance

Best mix	Moist, humus-rich, well-drained, slightly acidic to neutral loam; pH 4.5–7.5
Light	Bright indirect light (just back from a sunny window)
Ideal temperature	−15 to 28°C (5 to 82°F)
Watering	When the top 3–5 cm of soil is dry, roughly every 3–5 days in summer; reduce in winter

About Nikko Blue Bigleaf Hydrangea

Hydrangea macrophylla 'Nikko Blue' · also called Nikko Blue Hydrangea, Bigleaf Hydrangea · flowering

Nikko Blue is a classic mophead hydrangea bearing large, rounded flowerheads of intense blue (in acidic soils) or pink to mauve (in alkaline soils). It flowers on old wood, so correct pruning timing is critical. One of the best-known garden hydrangeas for borders and containers. All parts are toxic to pets and mildly toxic to humans.

Preferred mix: Moist, humus-rich, well-drained, slightly acidic to neutral loam; pH 4.5–7.5

Watch for — Wrong flower colour / fading: Blue requires soil pH 4.5–5.5 with available aluminium; pink occurs in alkaline soils. Use rainwater and ericaceous compost to maintain blue. Fading in strong sun is prevented by afternoon shade.

Why nikko blue bigleaf hydrangea needs this mix

Nikko Blue Bigleaf Hydrangea is a true acid-lover — it physically cannot take up iron above about pH 5.5, so an ericaceous mix is not optional, it is survival.

Nikko Blue Bigleaf Hydrangea has evolved on acidic, peaty ground and depends on soil fungi that only function in acid conditions — raise the pH and it starves even in "rich" soil.
In a too-alkaline mix iron and manganese lock up chemically, so the youngest leaves yellow between green veins (lime-induced chlorosis) and the plant fades out.
Its fine, shallow roots also want an open, free-draining structure, not a heavy clay or claggy compost.

For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.

What goes wrong with the wrong mix

The wrong soil is one of the most common reasons nikko blue bigleaf hydrangea struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:

Ordinary multipurpose or garden compost is far too alkaline for nikko blue bigleaf hydrangea — expect classic yellowing, weak growth and a slow decline over a season or two.
Hard tap water slowly pushes the pH up too, undoing a good mix; rainwater is strongly preferred for watering.
Lime, mushroom compost or wood ash anywhere near this plant is actively harmful.

Planting nikko blue bigleaf hydrangea in standard compost or limey garden soil. Without an acidic (ericaceous) medium it will yellow and fail no matter how well you water and feed it.

pH — does it matter for nikko blue bigleaf hydrangea?

This is the whole game: Nikko Blue Bigleaf Hydrangea needs pH 4.5-5.5. Test it, use ericaceous compost (and an ericaceous feed), and water with rainwater where you can to keep the pH from creeping up.

If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.

DIY mix vs a bagged one

Bagged ericaceous compost is the correct, easy base for nikko blue bigleaf hydrangea; just open it up with bark and grit per the ratio above. Do not try to acidify ordinary compost by guesswork — it rarely holds.

Drainage and the pot

Containers are often easier than open ground because you control the pH completely. Use a pot with good drainage and an ericaceous mix; never let it sit waterlogged.

Top up or refresh the ericaceous mix yearly and test the pH each spring — it naturally drifts upward over time, especially if watered with tap water. When the time comes, our repotting guide for nikko blue bigleaf hydrangea covers the timing and technique step by step.

Nikko Blue Bigleaf Hydrangea soil — frequently asked questions

What is the best soil mix for nikko blue bigleaf hydrangea?

3 parts ericaceous (acidic) compost : 1 part composted pine bark or pine needles : 1 part perlite or coarse grit. Nikko Blue Bigleaf Hydrangea has evolved on acidic, peaty ground and depends on soil fungi that only function in acid conditions — raise the pH and it starves even in "rich" soil.

Can I use normal potting soil for nikko blue bigleaf hydrangea?

Ordinary multipurpose or garden compost is far too alkaline for nikko blue bigleaf hydrangea — expect classic yellowing, weak growth and a slow decline over a season or two. Bagged ericaceous compost is the correct, easy base for nikko blue bigleaf hydrangea; just open it up with bark and grit per the ratio above. Do not try to acidify ordinary compost by guesswork — it rarely holds.

Does nikko blue bigleaf hydrangea need a special pH?

Should I buy a bagged mix or make my own for nikko blue bigleaf hydrangea?

How often should I refresh the soil for nikko blue bigleaf hydrangea?

Top up or refresh the ericaceous mix yearly and test the pH each spring — it naturally drifts upward over time, especially if watered with tap water. Containers are often easier than open ground because you control the pH completely. Use a pot with good drainage and an ericaceous mix; never let it sit waterlogged.