Whilst most plants prefer a neutral environment, there are exceptions. Here is a list of the exact pH preferences for some common plants, including fruits and vegetables. A guide like this may be included with many of the pH meters available.
Plants that like very acidic conditions (5.0-5.8 pH)
5.0-5.8 is considered very acidic for soil conditions. Plants that prefer this include:
Azalea
Heather
Hydrangea
Strawberry
Plants that like moderately acidic conditions (5.5-6.8 pH)
Moderately acidic levels are from 5.5-6.8 and some plants which prefer these conditions include:
Camellia
Carrot
Fuchsia
Rose
Plants that like slightly acidic conditions (6.0-6.8)
Plants that prefer the conditions just below neutral at between 6.0-6.8 include:
Broccoli
Lettuce
Pansy
Peony
Plants that prefer alkaline conditions (7.0-8.0 pH)
Soil conditions do not venture far into the alkaline side of the pH scale, but plants which prefer conditions just above neutral at 7.0-8.0 include:
