Soil pH for Plants: A Chart of Preferred Ranges

Most garden plants want pH 6.0 to 7.0, but blueberries, azaleas and brassicas sit well outside it. A reference table by crop and ornamental.

By Zakaria October 28, 2026 3 min read Save to Pinterest

Two cupped hands holding dry crumbling soil, fine grains falling through — Photo: StockSnap, Pixabay Content License, via Pixabay

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Most plants want pH 6.0 to 7.0. The ones that do not are worth knowing by name, because they fail in ordinary soil for reasons no fertilizer corrects.

The short answer

Most garden plants prefer pH 6.0 to 7.0, where the major nutrients are all reasonably available. Outside that band nutrients stay in the soil but become chemically locked: iron and manganese above about 7.5, phosphorus below about 5.5 — which is why a plant can show deficiency in soil full of the nutrient. Blueberries, cranberries and heathers need 4.5 to 5.5; rhododendrons, azaleas and camellias 4.5 to 6.0; lavender, rosemary, brassicas and asparagus tolerate 7.0 to 7.5 and above. Changing pH takes months to a year and reverts, so choosing plants to suit the soil usually beats correcting it.

Default target: 6.0–7.0
Nutrients lock up, they do not vanish, outside that range
Acid specialists: blueberry, cranberry, heather, rhododendron, azalea
Alkaline-tolerant: lavender, rosemary, brassicas, asparagus, lilac
Changing pH is slow and reverts — match plants to soil where you can

Vegetables

crop	preferred pH
Asparagus	6.5–7.5
Beans	6.0–7.0
Beets	6.5–7.5
Broccoli, cabbage, cauliflower	6.5–7.5
Carrots	6.0–6.8
Cucumber	6.0–7.0
Garlic and onions	6.0–7.0
Lettuce	6.0–7.0
Peas	6.0–7.5
Peppers	6.0–6.8
Potatoes	5.0–6.0
Spinach	6.5–7.5
Squash and pumpkin	6.0–7.0
Sweet corn	6.0–7.0
Tomatoes	6.0–6.8

Fruit

crop	preferred pH
Apple	6.0–7.0
Blackberry	5.5–6.5
Blueberry	4.5–5.5
Cranberry	4.0–5.5
Grape	6.0–7.0
Pear	6.0–7.0
Raspberry	5.5–6.5
Strawberry	5.5–6.5

Ornamentals and lawn

plant	preferred pH
Azalea, rhododendron, camellia	4.5–6.0
Heather	4.5–5.5
Hydrangea	5.0–6.5 (flower colour shifts with pH)
Rose	6.0–7.0
Clematis	6.5–7.5
Lavender, rosemary, sage, thyme	6.5–7.5
Lilac	6.5–7.5
Conifers (most)	5.0–6.0
Lawn grasses	6.0–7.0

Why pH matters more than feeding

Above about 7.5 iron and manganese lock up, which is what causes yellow leaves with green veins on a blueberry in neutral soil. Below about 5.5 phosphorus ties up and aluminium becomes available enough to damage roots. Fertilizer cannot fix either — only pH can.

Testing properly

Sample at root depth, four to six inches for most beds
Take five or six samples across the area and mix them
Avoid spots recently limed, fertilised or where ash was dumped
An extension lab test also reports nutrients and organic matter, which a probe cannot

Changing it, if you must

direction	material	notes
Raise	Garden lime	Months to register; retest before repeating
Raise, mildly	Wood ash	1/3 to 1/2 the strength of lime
Lower	Elemental sulfur	Slow, soil-biology dependent, most durable
Lower, faster	Aluminium sulfate	Quicker, easy to overdo, aluminium risk

Clay and high-organic soils resist change strongly; sandy soils move easily and revert just as fast.

Common questions

What pH do most plants prefer?

Between 6.0 and 7.0, slightly acidic to neutral, which is where nitrogen, phosphorus, potassium, calcium and magnesium are all reasonably available at once. Outside that band, nutrients do not disappear from the soil but they become chemically locked up — iron and manganese become unavailable above about 7.5, while phosphorus is tied up below about 5.5. That is why a plant can show a deficiency in soil that contains plenty of the nutrient.

Which plants need acidic soil?

Blueberries are the extreme case at 4.5 to 5.5, along with cranberries and most heathers. Rhododendrons, azaleas, camellias, pieris and gardenias want 4.5 to 6.0; raspberries, potatoes and most conifers prefer the lower end of the normal range at about 5.5 to 6.5. Trying to grow a blueberry in neutral soil produces yellow leaves with green veins — iron chlorosis — and nothing you feed it will fix that until the pH comes down.

Which plants tolerate alkaline soil?

Lavender, rosemary, sage, thyme, clematis, lilac, forsythia, beech and most brassicas all do well at 7.0 to 7.5 or a little above. Asparagus, beets, cabbage and cauliflower are the vegetables that genuinely prefer a touch of alkalinity, and brassicas benefit twice over because higher pH suppresses clubroot. Alkaline soil is far harder to acidify durably than acid soil is to lime, so choosing plants to suit it beats fighting it.

How do I test soil pH?

A laboratory test through an extension service is the accurate option and usually reports nutrients and organic matter as well. For a quick check, a probe meter or a chemical test kit is good enough to place soil within half a point if you take several samples from different parts of the garden and average them. Test at the depth roots occupy — four to six inches for most beds — and keep away from recently limed or fertilised spots, which skew a sample badly.

How do I change soil pH?

Garden lime raises pH and elemental sulfur or aluminium sulfate lowers it, both slowly and both best applied after a test tells you the starting point. Expect several months for a change to register and a year or more for a full point of movement, because soil is buffered — clay and high-organic soils resist change far more than sand. Wood ash also raises pH at roughly a third to a half the strength of lime. Retest before applying more.

Is it better to change pH or change plants?

Change plants, in most cases. Soil pH reverts towards its natural value as rainfall, parent rock and irrigation water reassert themselves, so holding an unnatural pH is an annual commitment. The exception is a contained situation — blueberries in a large pot of ericaceous compost, or a single raised bed of brassicas limed each year — where the volume of soil is small enough to manage. For a whole garden, work with what you have.

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