Soil Test Note – No.
H001
Dr. Gerald L. Klingaman
Extension Horticulturist - Ornamentals
OPTIMUM pH RANGES FOR ORNAMENTAL PLANTS
Very Acid
pH Between 4.8 and 5.5 |
Medium Acid
pH 5.5 to 6 |
Slight Acid
pH 6 to 7 |
Sweet Soils pH 7 and Above |
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Azalea |
African Violets |
Anemone |
Arborvitae |
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Blueberry |
Begonia |
Aster |
Barberry |
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Calla Lily |
Bleeding Hart |
Candytuft |
Calendula |
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Camellia Japonica |
Black Gum |
Canna |
Clematis |
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Gardenia |
Boxwood |
Carnation |
Deutzia |
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Hydrangea (blue) |
Cyclamen |
Centaurea |
Forget-me-nots |
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Huckleberry |
Cypress |
Chrysanthemum |
Geranium |
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Ferns: |
Delphinium |
Columbine |
Hydrangea (pink) |
|
There
are many ferns and
they vary from acid
to alkaline in soil requirements |
Easter Lily Holly sp. Iris, Japanese Lily |
Cosmos Crocus Daffodil Dahlia |
Junipers Lupine Morning Glory Nasturtium |
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Heather |
Oak |
Dogwood |
Redbud |
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Magnolia |
Pecan |
Gladiolus |
Sweet Peas |
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Pine |
Phlox |
Hawthorne |
Yucca |
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Rhododendron |
Sweetgum |
Hollyhock |
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Vinca |
Hyacinth |
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Weigela |
Iris (bearded) |
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Viburnum |
Ivy, English |
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Larkspur |
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Lilac |
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Marigold |
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Narcissus |
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Pansy |
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Peony |
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Primrose |
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Poinsettia |
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Poppy |
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Rose |
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Petunias |
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Snapdragon |
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Stocks |
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Tulip |
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Violets |
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Wisteria |
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Yucca |
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Zinnia |
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NOTE: Many
of these plants will grow without problems in a wide range of soil pH levels.
LIME
REQUIRED TO RAISE SOIL pH TO SPECIFIC LEVELS1
Soil pH Change
From |
Exchangeable (Soil Test) Calcium,
Lbs. Per Acre
|
||
Below 800
|
800-2,500 |
2,500 and above |
|
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|
Lbs. Ground Limestone Per 1,000 Sq. Ft.2 |
||
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4.5 to 6.5 4.5 to 7.0 |
90 115 |
140 140 |
185 230 |
|
5.0 to 6.5 5.0 to 7.0 |
70 90 |
115 140 |
140 185 |
|
5.5 to 6.5 5.5 to 7.0 |
45 70 |
90 115 |
115 140 |
|
6.0 to 7.0 |
45 |
70 |
90 |
|
6.5 to 7.0 |
23 |
35 |
45 |
1 Mix the specified
rates thoroughly with the 6- to 7-inch layer of soil. For established plants, split into two applications
6 months to one
2
Examples:
a.
For rates per 300 sq.
ft.:
(1)
Limestone – Take 1/3 of the amount specified for 1,000 sq.
ft.
(2)
Hydrated Lime – Take ¼ of the amount of ground limestone per
1,000 sq. ft.
b.
For rates per 100 sq. ft.:
(1)
Limestone – Take 1/10 of the amount of specified for 1,000
sq. ft.
(2) Hydrated Lime – Multiply .075 x the amount of ground limestone specified
for 1,000 sq. ft.
MATERIALS REQUIRED TO LOWER SOIL pH TO SPECIFIC LEVELS
Use
the Following Table for Each 100 Square Feet1
(Multiply
by 436 for lbs/A)
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Add
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Add
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To Change
From: |
Wettable Aluminum3 Sulfur or Sulfate (lbs) (lbs) |
To Change pH From: |
Wettable Aluminum3
Sulfur or Sulfate
(lbs) (lbs) |
||
|
8.0 to 7.0 8.0 to 6.5 8.0 to 6.0 8.0 to 5.5 8.0 to 5.0 7.5 to 7.0 7.5 to 6.5 7.5 to 6.0 7.5 to 5.5 7.5 to 5.0 7.5 to 4.5 7.0 to 6.5 7.0 to 6.0 |
2 3 4 5 6 1 2 3 4 5 6 1 2 |
3.0 4.5 6.02 7.52 9.02 1.5 3.0 4.5 6.02 7.52 9.02 1.5 3.0 |
7.0 to 5.5 7.0 to 5.0 7.0 to 4.5 6.5 to 6.0 6.5 to 5.5 6.5 to 5.0 6.5 to 4.5 6.0 to 5.5 6.0 to 5.0 6.0 to 4.5 5.5 to 5.0 5.5 to 4.5 5.0 to 4.5 |
3 4 5 1 2 3 4 1 2 3 1 2 1 |
4.5 6.02 7.52 1.5 3.0 4.5 6.02 1.5 3.0 4.5 1.5 3.0 1.5 |
1Aluminum sulfate is faster in reaction than sulfur. The two materials may be applied together (half of each).
Incorporate
2 Rates higher than 4.5 lbs. Per 100 sq. ft. can cause excess soluble salt problems. Split the amount in half and apply
in the spring and fall.
3 Aluminum
sulfate is much less effective in reducing pH than wettable sulfur but is
quicker acting than flowers of sulfur and usually available. More frequent
applications may be necessary. Sample again within a year to evaluate reduction in pH.
April, 1995
The Arkansas Cooperative Extension
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