Soil with a pH that is higher than 7.0 is considered alkaline. Alkaline soils are mostly found in areas with dry climates, whereas moist climates tend to have more acidic soils. This is not always the case, however, as soil on top of limestone will almost always be alkaline, whether in a wet or dry climate. Many different types of plants, including trees, shrubs, vines and some vegetables, thrive in alkaline soil.
A tree is a woody plant with a main trunk and often a distinctive crown. Trees are also perennial, in that they survive longer than two years. The following trees thrive in alkaline soil:
Cedar elm (Ulmus crassifolia) Holly/Holm oak (Quercus ilex) Olive tree (Olea europaea) Japanese plum (Eriobotrya japonica) Asian persimmon (Diospyros kaki)
Shrubs are plants with woody stems but with relatively low overall height. Like trees, shrubs are also perennial. Many types of shrubs grow well in alkaline soil, including:
Japanese quince (Chaenomeles japonica) Littleleaf boxwood (Buxus microphylla) Feathery cassia (Cassia artemisioides) Daphniphyllum (Daphniphyllum humile) Silverthorn (Elaeagnus pungens) Heather (Erica melanthera) Cassina (Ilex vomitoria) Lavender (Lavandula officinalis)
A vine is a plant with weak stems that supports itself by creeping, climbing or twining along a surface. The following vines thrive in alkaline soil:
Japanese honeysuckle (Lonicera halliana) Chilean jasmine (Mandevilla suaveolens) Bluebell creeper (Sollya heterophylla) Common bean (Phaseolus)
Herbaceous plants, more commonly known as "herbs," are plants with non-wood stems that die back into the ground each winter. Herbs can be annual, biennial or perennial. Several types of herbs need alkaline soil to grow, including:
Persian rockcress (Aethionema cordifolium) Japanese anemone (Anemone japonica) Kenilworth ivy (Cymbalaria muralis) Baby's Breath (Gypsophila elegans) Goldencup/Mexican Tulip Poppy (Hunnemannia fumariifolia)
Sweet Pea (Lathyrus odoratus)
A vegetable is a plant cultivated for the part of the plant that is edible, specifically the root, leaf and/or flower. Although all of the following vegetables grow in alkaline soil, they do still have very different growing environments. Asparagus, for example, grows in soil with good internal drainage. Mushrooms, on the other hand, require high humidity in their second stage of growth.
Asparagus Okra Parsley Yams
Plants That May Indicate Alkaline Soil
Plants that may indicate alkaline soil are mostly weeds, although one would be hard-pressed to find someone who considered hydrangeas to be weeds (generally thought to be plants that are either useless or ugly). Although these plants are not a substitute for actual pH testing, the presence of any of the following plants can give you an idea of which end of the pH spectrum your soil tends toward.
Dandelions (Taraxacum officinale) Chickweed (Stellaria media) Queen Anne's Lace (Daucus carota) Goosefoot (Chenopodiaceae) Chicory (Cichorium intybus) Hydrangeas (if the blooms are blue, the soil is acidic, whereas they are pink when grown in alkaline soil)