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pH preferences of common flowers, grasses and food crops

Hotwired has been very patiently instructing me on how to fix my poor strawberries over in the Strawberry Lovers group and we’ve been discussing the importance of pH for nutrient uptake in plants and soil pH modification. This all came around to me being very irritated about the misreable quality of pH information found on the web. Then today I ran across this publication when I purchased a soil pH kit for my current project. A lot of the numbers are different than what I was finding on the web but seem to make more sense. I thought others might find it useful. If you have questions, I’m sure Hotwired would be kind enough to discuss it with you. I’m pretty sure he has dreams about this stuff at night!

Hotwired’s adjusted list

Flowers, Trees & Shrubs:
Azalea 4 ½ – 5 ½
African Violet 6 – 7
Ageratum 6 – 7
Alyssum 6 – 7
Anemone 6 – 7 ½
Arborvitae 6 – 7
Aster 5 – 6
Amaryllis 5 – 6
Alder 6 – 7
Andromeda 5 – 6
Ash 6 – 7
Begonia 5 ½ – 6 ½
Butterfly Bush 6 – 6 ½
Bottlebrush 6 – 7 ½
Birch 4 ½ – 6
Bayberry 4 ½ – 6
Beech 6 – 7
Boxwood 6 – 7
Batchelor Button 6 ½ – 7 ½
Cedar 5 – 7
Cypress 5 – 6
Cottoneaster 6 – 7
Cottonwood 6 – 7 ½
Chestnut 5 – 6 ½
Carnation 6 – 7 ½
Caladium 5 ½ – 6 ½
Canna 6 – 7 ½
Croton 5 – 7
Chrysanthemum 5 ½ – 6 ½
China aster 5 – 7
Dogwood 6 – 7
Daffodil 6 – 8
Dahlia 6 – 7
Delphinium 6 – 7 ½
Deutzia 6 – 7
Daphne 5 ½ – 6 ½
Elm 6 – 7
Euonymus 6 – 7
Eucalyptus 6 ½ – 7 ½
Forsythia 5 ½ – 6 ½
Fir 5 ½ – 7
Fern 5 – 6
Fuchsia 5 ½ – 6 ½
Gardenia 5 – 6
Gladiolus 5 ½ – 6 ½
Geranium 6 – 7 ½
Hibiscus 5 – 6 1/2
Holly 5 – 6
Hydrangea (Blue) 4 ½ – 5 ½
Hydrangea (Pink) 6 ½ – 7 ½
Hawthorn 6 – 7 ½
Hyacinth 6 – 7
Hazel (Witch) 6 – 7
Hemlock 5 – 6
Honeysuckle 6 – 7
Horsechestnut 6 – 7
Iris 6 – 6 ½
Ilex 5 – 6
Ivy 6 – 7
Juniper 5 – 6
Lantana 5 ½ – 6 ½
Lily 5 – 6
Larch 6 – 7
Laurel 5 – 6
Locust 6 – 7
Lilac 6 – 7
Linden 6 – 7
Lily of the Valley 5 – 6
Magnolia 5 – 6
Marigold 5 ½ – 7
Maple 6 ½ – 7 ½
Mulberry 6 – 7
Narcissus 6 – 6 ½
Oak 5 – 6
Orchid 4 ½ – 6
Palm 5 ½ – 7
Pansy 5 – 6 ½
Peony 6 – 7 ½
Periwinkle 6 – 7 ½
Petunia 5 ½ – 7
Phlox 5 – 6
Pine 5 – 6
Plane Tree 6 – 7
Poinsetta 6 – 7
Poplar 6 – 7
Privet 6 – 7
Quince 6 – 7
Rose 5 ½ – 7
Rhododendron 4 ½ – 5 ½
Snapdragon 6 – 7
Spirea 6 – 7
Spruce 5 – 6
Sweetgum 6 – 7
Sycamore 6 – 7 ½
Tulip 6 – 6 ½
Tupelo 6 – 7
Tuliptree 6 – 7
Verbena 6 – 7 ½
Violet 6 – 7 ½
Viburnum 6 – 7
Walnut 6 – 7
Weigelia 6 – 7
Willow 5 – 7
Wisteria 6 – 7 ½
Yew 6 – 7
Yucca 6 – 7
Zinnia 5 ½ – 7

Grasses
Blue (Ky) 5 ½ – 7 ½
Bent 5 ½ – 6 ½
Bermuda 6 – 7
Buffalo 6 – 7 ½
Clover 5 ½ – 7
Fescue (red) 5 ½ – 6 ½
Fescue (tall) 6 ½ – 7 ½
Rye 5 ½ – 8
Rye (Perennial) 6 – 7
St. Augustine – 6 – 7 ½
Zoysea – 4 ½ – 7 ½

Fruit and Vegetables
Alfalfa 7 – 7 ½
Apple 5 ½ – 6 ½
Artichoke 6 – 6 ½
Asparagus 6 – 6 ½
Barley 7 – 7 ½
Bean 5 ½ – 6 ½
Beets 6 – 7
Blackberry 5 ½ – 6 ½
Broccoli 6 – 6 ½
Brussel Sprout 6 – 6 ½
Cabbage 6 – 6 ½
Cantaloupe 6 – 6 ½
Cherry 6 – 6 ½
Cauliflower 5 ½ – 6 ½
Chive 6 – 6 ½
Corn 5 ½ – 6 ½
Cranberry 4 ½ – 5
Carrot 5 ½ – 6 ½
Cucumber 6 – 6 ½
Celery 6 – 6 ½
Eggplant 5 ½ – 6 ½
Grapes 5 ½ – 6 ½
Grapefruit 6 – 6 ½
Lemon 7 –7 ½
Lettuce 6 – 6 ½
Lima Bean 6 – 6 ½
Mushroom 6 – 6 ½
Onion 5 ½ – 6 ½
Peas 6 – 6 ½
Parsley 5 ½ – 6 ½
Peach 6 – 61
Pear 6 – 6 ½
Pepper 5 ½ – 6 ½
Potato (Sweet) 6 – 6 ½
Potato 5 – 5 ½
Plum 6 – 6 ½
Pumpkin 5 ½ – 6 ½
Rhubarb 5 ½ – 6 ½
Rice 5 – 6 ½
Rye 5 ½ – 6 ½
Radish 6 – 6 ½
Soybean 6 – 6 ½
Spinach 6 – 7
Squash 5 ½ – 6 ½
Strawberry 5 – 5 ½
Turnip 5 ½ – 6 ½
Tomato 5 ½ – 6 ½
Watermelon 5 ½ – 6 ½
Wheat 6 – 7

Posted over 4 years ago | Last edited over 4 years ago

I’ll continue updating my list with optimum values and we can eventually edit yours to incorporate the additional data. It would be nice to have a good reference available and this group is probably more appropriate that Chit Chat

Posted over 4 years ago
N20863

N20863

Folia Helper

United States6b

Just out of curiosity, how much effect does the pH of the water you use have? I guess it would be different for gardens, containers and raised beds but I imagine this would have some impact as well, no?

Posted over 4 years ago

It does have an effect, but minerals in the soil have more of an influence. I feed my strawberries and blueberry bushes with Jack’s Classic Acid Special which has a high sulfur content. My garden soil’s natural Ph is 6.5, and a once a week feeding maintains a 5.0 Ph pretty nicely. I’ve never had my soil below 4.8, however I imagine you could overdo it.

Posted over 4 years ago
N20863

N20863

Folia Helper

United States6b

Gotcha! Thanks @HW. Enjoy the cruise!!!

Posted over 4 years ago

When we have symptoms of nutrient deficiency, often we try to treat the symptom rather than the cause. Nutrition Deficiencies are often caused by the wrong Ph. Ph has significant effect on the plants ability to absorb nutrients. Each vegetable has an optimum Ph.

If we look at Tomatoes, the Optimum Ph is 6.5. For Tomatoes, Nitrogen absorption is blocked at ph levels of 4.0- 5.5. It doesn’t matter how rich in Nitrogen your soil is, if your Ph is too low, then the plant can’t absorb it. Nitrogen is absorbed best in soil at a ph level of 6.0 to 7.0. Anything out of that range will contribute to a nitrogen deficiency.

Potassium absorption is blocked at ph levels of 4.0 to 5.5 for tomatoes. Potassium is absorbed best in soil at a ph level of 6.0 to 7.5, while anything out of this range will contribute to a Potassium deficiency.

Phosphorus absorption is blocked at ph levels of 4.0 to 5.5 for tomatoes. Phosphorus is absorbed best in soil at a ph level of 6.0 to 7.5. Anything out of the ranges listed will contribute to a Phosphorus deficiency.

This is another reason that diagnosing Nutritional Symptoms is so difficult.

Posted about 4 years ago

@Vsecrets – I once had a similar list but it got slimed and eaten by slugs! Thanks for posting it here.
@Hotwired – Really useful info re. absorbtion, explains a lot of the issues I’ve had in some of my problem spots so maybe now I can make some more useful changes and amendments.

Thanks to you both.

Posted about 4 years ago

Hotwired’s comment about absorbtion got my brain going and I wondered if there were any diagrams to illustrate as I remember info better if it’s visual, found a page that has a chart showing “The effect of soil pH on availability of plant nutrients (From Hunger Signs in Crops, edited by H.B. Sprague, 1964, pg. 18)” which will remind me that this is info to bear in mind long after my brain has forgotten the science of it all. Would love some Hotwired feedback if the chart has any errors based on your great practical knowledge of real life planting.

Posted about 4 years ago
TropicanaRoses

TropicanaRoses

Folia Helper

United States7

Wow. I was looking for a Caladium group to join and the search brought me here. :) This info I will be saving to a PDF. Very good stuff in here. THanks for posting guys!!

Posted over 3 years ago

Hi there! You're reading a conversation in the Plant Nutrition, Soil Amendments & Fertilizers/Fertilisers group on Folia.