Item 1. Soil Preferences of Plants (pH Readings)

Since practically no scientific work has been done to establish standards and limits of plant tolerances for acid or alkaline soils, most of the figures on pH range are based on observations by many authorities. The ranges presented here are not hard and fast read­ings which must be followed to the exact fraction given. (Remember that the pH scale of soil solutions runs from 1.0 [acid] to 14.0 [alkaline], with 7.0 neutral.)

The ability to survive under wide variation of soil is shared by many plants, yet a few are quite exacting in their requirements. When difficulty is experienced in holding a soil to a certain range, the addition of more organic matter will often override the harmful effects of too high or too low a pH.

Many of these figures might be questioned by those who have grown specific plants under other conditions. For example, while 5.5 to 6.9 is given as the proper range for roses, I have seen them grown at readings as high as 8.0 and as low as 4.8. However, when the gardener is striving for healthy plants with generous bloom, he will in general have fewer problems to overcome if he keeps his soil in the range suggested.

Since the principal use of this list will be to determine what plants can be grown under existing conditions, it has been arranged by soil reaction readings, so that all the subjects that can be grown together can be seen at a glance. Those who wish to study the subject more intensely are referred to "Soil Reaction Preferences of Plants," by C. H. Spurway, Special Bulletin 306 of the Michigan State Agricul­tural Experiment Station, East Lansing, Michigan. This lists thousands of plants, including weeds, trees, shrubs, groundcovers, an­nuals and perennials as well as farm crops and fruits.

 

pH

Range

Type

Species & Genera

4.0

to 5.0

SHRUBS

Andromeda, Cornus canadensis, Heaths (Ledum and Leiophyllum), Pieris,

4.0

to 5.5

SHRUBS

Potentilla, Magnolia glauca, Vaccinium Ilex

4.0

to 6.5

VEGETABLE

Dock (Rumex acetosa) Arctostaphylos,

4.5

to 5.5

SHRUBS

Blue Hydrangea, Rho­dodendron Rhode Island Bent Scabiosa

4.5

to 6.0

GRASS

Azalea, Gardenia Irish

4.8

to 7.5

ANNUAL

Potato, Sweet Potato

5.0

to 5.5

SHRUBS

Redtop

5.0

to 6.0

VEGETABLES
GRASS
SHRUBS

Acer pennsylvanicum & A. sfncatum, Aronia, Benzoin, Betula, Callicarpa, Camellia, Ceanothus, Chamaedaphne, Chionanthus, Comptonia, Corylopsis, Cytisus, Fothergilla, Indigofera, Kalmia, Leucothoe, Lyonia, Magnolia grandi-flora, M. soulangeana & M. stellata, Myrica, Nandina, Photinia, Skimmia, Stephanandra, Styrax, Vaccinium (in high organic soils) Aconitum papellus, Androsace Parsley
Apple, Oriental crabapples

 

 

FLOWERS

Enkianthus

5.0

to 6.9

VEGETABLE
FRUIT
SHRUB FLOWERS

Anemone globosa, A. halleri & A. ver-nalis, Pulsatilla vernalis Bellingham hybrids and L. bolanderi, canadensis, catesbaei, elegans, formo-sanum, grayi, japonicum, kellogt, phtl-adelphicum

5.5

to 6.3

LILIES

Carrot, Celery, Chicory, Corn, Cucum­ber, Dandelion, Eggplant, Endive, Onion, Parsnip, Pepper, Pumpkin, Rhu­barb, Squash, Turnip, Watermelon

5.5

to 6.9

VEGETABLES
SHRUBS FLOWERS

Roses
Amaryllis, Aster (perennial), Begonia, Calendula, Lantana, Pansy, Phlox drummondi, Nasturtium, Portulaca, Salvia splendens

5.5

to 7.5

FLOWERS
VEGETABLES GRASSES

Chrysanthemum, Marigold (Tagetes) Cauliflower, Collards, Tomato Poa pratensis

6.0

to 6.9

VEGETABLES

Beans (snap, lima, pole & soy), Broc­coli, Celery, Chives, Garden Cress, Horseradish, Lettuce, Mangel, Musk-melon, Onion, Radish Agrostis (all

 

 

GRASSES

Bents except Rhode Is­land), Poa trivialis, Bermuda Amelanchier,

 

 

SHRUBS

Amygdalus communis, Aralia, Cornus florida, Corylus, Exo-chorda, Genista, Hamamelis, Pink Hy­drangea, Itea, Prunus (cherries & apri­cots), Symplocos
Acanthus mollis, Astilbe, Calceolaria,

 

 

FLOWERS

China Aster, Cineraria, Clarkia, Coleus, Fuchsia, Gloxinia, Gladiolus, Helian-themum, Heuchera, Iberis, Iris ger-manica, LUium aura turn, L. bakerianum, L. philippinense, Narcissus, Poinsettia, Primula, Saintpaulia, Schizanthus, Tu­lips

6.0

to 7.5

VEGETABLES

Asparagus, Beets, Brussels Sprouts, Cabbage, Chinese Cabbage, Kale, Kohl­rabi, Mustard, Peas, Salsify, Spinach, Swiss Chard

 

 

GRASSES

Orchard grass, Perennial & Italian Rye-grasses, (and crabgrass) L. Amabile, Backhouse hybrids, L. Browni, L.

 

 

LILIES

Bulbiferum, L. caUosum, L. candidum, L. cernuum, L. chalcedoni-cum, L. concolor, L. croceum, L. dauri-cum, L. davidi, L. hansoni, L. henryi, L. longifiorutn, L. mart agon, L. monadelphicum, L. pardalinum, L. farryi, L. regale, L. sargentiae, L. speciosum, L. tenuijolium, L. testaceum, L. umbellatum

 

 

SHRUBS

Ailanthus, Daphne cneorum, Forsythia, Fraxinus, Ribes (cultivated currants), Viburnum

 

 

FLOWERS

Ageratum, Alyssum, Anagallis, Anchusa, Antirrhinum, Aquilegia, Aubrietia, Di-anthus (carnation), Celosia, Centaurea, Cynoglossum,

 

 

 

Dahlia, Delphinium (an­nual & perennial), Dicentra spectabilis, Digitalis, Dimorphotheca, Gaillardia, Geum, Godetia, Ipomaea, Gypsophila, Lobelia, Lupinus, Mirabilis jalapa, Nigella, Papaver, Petunia, Salvia jarin-acea, Vinca rosea Garlic, Leek,

6.0

to 8.0

VEGETABLES SHRUBS

Watercress Abelia, Acacia, Acer (except A. penn-sylvanicum & A. spicatum), Aesculus, Alnus, Amorpha, Berberis, Buddleia, Buxus, Calycanthus, Cephalanthus, Chaenomeles (Cydonia), Citrus, Cornus (except C. florida & C. canadensis), Cotoneaster, Deutzia, Dirca, Eleagnus, Euonymus, Hibiscus, Hypericum, Ker-ria, Kolkwitzia, Laburnum, Ligustrum, Lonicera, Mahonia, Malus, Philadel-phus, Prunus (ornamental varieties), Pyracantha, Rhamnus, Rhodotypos, Rhus, Ribes alpinum, Robinia, Sambucus, Sorbaria, Spirea, Symphoricarpos, Syringa, Tamarix, Weigela Adonis, Althaea,

 

 

FLOWERS

Amaranthus, Anemone alpina & A. cylindrica, Crocus, Gilia, Heliotrope, Mesembryanthemum, Myosotis, Paeonia, Phlox (perennial)

6.5

to 7.5

FLOWER
MUSHROOM

Lupinus (western varieties)
Meadow mushroom (cultivated)

7.0

to 8.0

SHRUBS

Baccharis, Daphne mezereum

Two flowers are so tolerant that they will grow in any pH from 5.0 to 8.0. These are the Cosmos and Mignonette.

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