Soil pH by Crop: the Reference Table for Vegetables, Fruit and Lawns

Soil pH by crop is the single number that decides whether a plant can reach the nutrients you are paying for: almost every essential element has a pH band where it is available, and outside that band a well-fertilised soil still grows a deficient plant. This reference gives the target pH for vegetables, fruit, berries, herbs and ornamentals in one table, then works through the crops that have no dedicated page of their own (lettuce, strawberry, raspberry and blackberry) with the “what goes wrong first” note for each band.

pH is measured on a 0–14 scale of hydrogen ion concentration, and each whole step is a tenfold change: pH 6 is ten times more acidic than pH 7. Most vegetables sit in a narrow band from 6.0 to 7.0, while the ericaceous group (blueberries, azaleas, rhododendrons) sits a full step lower.

Soil pH reference table by crop

Ranges are the working target for outdoor growing in mineral soil. Container media are usually held a little lower than the same crop in the ground, because peat-based mixes resist pH change.

Crop	Target pH	What goes wrong outside the band
Blueberry	4.5 – 5.5	Iron and manganese chlorosis above 6.0; yield collapses first, then leaves yellow between the veins
Azalea, rhododendron, camellia	4.5 – 6.0	Iron chlorosis; growth stops and buds abort
Potato	5.0 – 6.0	Common scab increases sharply above 6.0, the classic reason to keep a potato patch slightly acid
Sweet potato	5.5 – 6.5	Knot nematode pressure and poor tuber set above 7.0
Strawberry	5.5 – 6.5	Manganese toxicity below 5.5; iron chlorosis above 7.0; fruit is small and dull
Raspberry, blackberry	5.5 – 6.5	Calcium takes over above 6.8, magnesium drops, leaf edge scorch and weak canes
Grape	5.5 – 6.5	Iron chlorosis on calcareous soils; poor colour and delayed ripening
Tomato, pepper, eggplant	6.0 – 6.8	Blossom end rot is a calcium-uptake problem made worse by pH swings; iron chlorosis above 7.5
Cucumber, squash, melon	6.0 – 7.0	Magnesium shortage above 7.2; slow establishment below 5.5
Corn	5.8 – 7.0	Aluminium toxicity in strongly acid sand; zinc deficiency on high-pH clay
Bean, pea	6.0 – 7.0	Nitrogen fixation fails below 5.5, rhizobium will not inoculate properly
Lettuce, spinach, chard	6.0 – 7.0	Tipburn and uneven growth outside the band; lettuce struggles below 5.8
Carrot, parsnip, radish	6.0 – 6.8	Forking and forking root on compacted high-pH soil; scabby skin on carrots below 5.8
Cabbage, broccoli, cauliflower, kale	6.0 – 7.5	Clubroot thrives below 6.0, this group genuinely wants lime
Onion, garlic, leek	6.0 – 7.0	Thick necks and bolting on low pH; white rot worse on acid soil
Asparagus	6.5 – 7.5	The most lime-tolerant vegetable; crowns weaken below 6.0
Herbs (basil, parsley, thyme, rosemary)	6.0 – 7.0	Woody Mediterranean herbs tolerate 7.5; basil is the least tolerant
Hydrangea	5.2 – 6.5	Blue below 5.5, pink above 6.0, see the hydrangea feeding and pH guide
Lavender	6.5 – 8.0	Root rot in acid wet soil; the one common ornamental that prefers alkaline
Lawn turf	6.0 – 7.0	Below 5.5 moss takes over; above 7.5 iron and manganese lock out

The rules that apply to every crop

• Most vegetables want 6.0–7.0. That band maximises the availability of nitrogen, phosphorus, potassium, calcium, magnesium and the micronutrients simultaneously. There is no pH where everything peaks, so the optimum is the compromise.
• Availability falls faster than deficiency shows. Phosphorus ties up with calcium above pH 7.5 and with iron/aluminium below pH 5.5; the plant looks fine for a season or two while the soil runs down.
• Liming raises pH slowly, acidifying raises it fast. Elemental sulphur and aluminium sulfate move pH within weeks; ag lime takes a season. Plan on a test–treat–wait–retest cycle.
• Texture changes how much amendment you need. A clay loam buffers pH and holds it near where you put it; a sand will drift back with every irrigation.
• Test at the right depth and time. Sample to 10–15 cm in the root zone, several points per bed, mixed into one sample, in autumn or early spring before you amend.

Crops with no dedicated page yet

Soil pH for lettuce

Lettuce grows from pH 6.0 to 7.0, with 6.2–6.8 the sweet spot. Below 5.8 the plant takes up manganese and aluminium too readily and growth is uneven; above 7.2 boron and iron become unavailable and the inner leaves cup and brown. Lettuce is a shallow feeder, so the top 15 cm matters more than the subsoil, in raised beds, a mix that starts at 6.4 rarely needs correcting.

Soil pH for strawberries

Strawberries want pH 5.5–6.5. Above 7.0 you get iron chlorosis in the newest leaves and berries that are pale and low in sugar; below 5.5 manganese builds up and leaf margins blacken. Strawberry beds also carry a lot of fertiliser history, so measure rather than assume: repeated ammonium-based feeding drifts the bed downward, and lime or dolomite drifts it up.

Soil pH for raspberries and blackberries

Both brambles sit at pH 5.5–6.5. They are less fussy than blueberries but intolerant of alkaline clay: above 7.0 the roots take up calcium preferentially, magnesium drops, and the classic symptom is scorched leaf edges on the canes in high summer. Plant into a prepared trench with organic matter, keep the crown above the wet zone, and check pH before planting because mature beds are expensive to move.

Soil pH for grape

Grapes prefer pH 5.5–6.5 and are often grown on land too poor for anything else, which is why they tolerate low fertility but not high pH. On calcareous soils they show iron chlorosis in the young leaves while the veins stay green, the same pattern as blueberries on lime, but at a completely different pH, and the fix is chelated iron plus better rootzone drainage rather than acidifying the whole vineyard.

Working from a concentration instead of a pH reading? The pH converter calculator turns any one of pH, hydrogen ion concentration (mol/L, µmol/L or mg/L), pOH or hydroxide into the whole set, so a lab number in any of those units lands on this table.

What to do with the number

1. Test first. A kit gives you one point; a lab gives you pH, CEC, buffer pH and nutrient levels, which is the difference between knowing the pH and knowing how much lime it will take to move it.
2. Split the garden by pH band, not by bed. Most gardens have one acidic corner (under conifers or on sand) and one alkaline corner (near a concrete path or on clay).
3. Amend the whole band, then re-test in 4–8 weeks for acidifying or 3–6 months for lime.
4. Choose crops to suit the pH you have where amending is impractical: this table is as much a planting guide as a correction guide.

The full chemistry of the scale is on the soil pH chart, the practical tests are covered in testing soil pH at home, and the vegetable-specific detail for tomatoes, peppers, potatoes and onions is in soil pH for tomatoes, peppers, potatoes and onions. To bring a bed into range, use the lime and CEC guide to raise pH or the acidification guide to lower it.

Every crop in the table above has a full entry (soil pH range, sunlight, water, traits and safety) in the plant pH database, where you can filter to the exact band you have measured.

Sources

• Soil pH — Colorado State University Extension; backs Crops with no dedicated page yet Soil pH for lettuce Lettuce grows from pH 6.0 to 7.0 , with 6.2–6.8 the sweet spot..
• Nutrient Management course notes: soil acidity, liming and carbonate equilibrium — Cornell University; backs Phosphorus ties up with calcium above pH 7.5 and with iron/aluminium below pH 5.5; the plant looks fine for a season or two while the soil runs down..
• Soil Testing — Extension Winnebago County, Wisconsin; backs Sample to 10–15 cm in the root zone, several points per bed, mixed into one sample, in autumn or early spring before you amend..
• How To Change Your Soil's pH — Iowa State University Extension and Outreach; backs Amend the whole band , then re-test in 4–8 weeks for acidifying or 3–6 months for lime..