Soil pH Levels for Plants

Optimum Soil pH Levels for Trees, Shrubs, Vegetables, and Flowers

August 13, 2019
Hydrangea Flower Colors
Pixabay

What is your soil’s pH level? Every plant prefers a different level of acidity. Use this soil pH chart to find which pH level is best for your garden plants. Then, learn how to adjust it accordingly!

The Secret of Soil pH

Having the right soil pH is key to growing a healthy garden, but it’s a factor that’s often overlooked in favor of nutrient levels and soil consistency. While these are also crucial things to consider, the pH of the soil plays a major role in how well your plants can absorb the nutrients you provide them, so it’s important to get it right!

The wrong pH often won’t kill plants outright, but it can affect their growth and result in subpar blooms or crops, depending on how sensitive the plant is. In actuality, many plants are able to adapt to a range of pH levels. Hydrangeas, for example, produce different colored flowers depending on whether they’re grown in acidic or alkaline soil.

A pH of 6.5 is just about right for most home gardens, since most plants thrive in the 6.0 to 7.0 (slightly acidic to neutral) range. Some plants (blueberries, azaleas) prefer more acidic soil, while a few (ferns, asparagus) do best in soil that is neutral to slightly alkaline.

How do you find out your soil pH? To do a simple pH test, you can acquire a soil pH test kit online or from a local garden store. However, for a similar cost (or even for free), you may be able to have your soil tested by your state Cooperative Extension, which can provide a much more in-depth analysis of your soil (including nutrient levels and other helpful bits of information). 

Here’s another way to figure out your soil type.

How Do You Adjust Soil pH?

Once you figure out your soil pH, it may be necessary to adjust it to suit the needs of the plants you’re growing. The level of acidity will specify the amount of soil amendment that is needed to bring it up or down to the appropriate level. Acidic (“sour”) soil is counteracted by applying finely ground limestone or wood ash, and alkaline (“sweet”) soil is typically treated with gypsum (calcium sulfate), ground sulfur, or compost.

Read more about preparing soil for planting.

Optimum Soil pH Levels for Plants

Common Name Optimum pH Range

Trees and Shrubs

Apple 5.0-6.5
Ash 6.0-7.5
Azalea 4.5-6.0
Basswood 6.0-7.5
Beautybush 6.0-7.5
Birch 5.0-6.5
Blackberry 5.0-6.0
Blueberry 4.0-6.0
Boxwood 6.0-7.5
Cherry, sour 6.0-7.0
Chestnut 5.0-6.5
Crab apple 6.0-7.5
Dogwood 5.0-7.0
Elder, box 6.0-8.0
Fir, balsam 5.0-6.0
Fir, Douglas 6.0-7.0
Hemlock 5.0-6.0
Hydrangea, blue-flowered 4.0-5.0
Hydrangea, pink-flowered 6.0-7.0
Juniper 5.0-6.0
Laurel, mountain 4.5-6.0
Lemon 6.0-7.5
Lilac 6.0-7.5
Maple, sugar 6.0-7.5
Oak, white 5.0-6.5
Orange 6.0-7.5
Peach 6.0-7.0
Pear 6.0-7.5
Pecan 6.4-8.0
Pine, red 5.0-6.0
Pine, white 4.5-6.0
Plum 6.0-8.0
Raspberry, red 5.5-7.0
Rhododendron 4.5-6.0
Spruce 5.0-6.0
Walnut, black 6.0-8.0
Willow 6.0-8.0

Vegetables

Asparagus 6.0-8.0
Bean, pole 6.0-7.5
Beet 6.0-7.5
Broccoli 6.0-7.0
Brussels sprout 6.0-7.5
Cabbage 6.0-7.0
Carrot 5.5-7.0
Cauliflower 5.5-7.5
Celery 5.8-7.0
Chive 6.0-7.0
Cucumber 5.5-7.0
Garlic 5.5-8.0
Kale 6.0-7.5
Lettuce 6.0-7.0
Pea, sweet 6.0-7.5
Pepper, sweet 5.5-7.0
Potato 4.8-6.5
Pumpkin 5.5-7.5
Radish 6.0-7.0
Spinach 6.0-7.5
Squash, crookneck 6.0-7.5
Squash, Hubbard 5.5-7.0
Tomato 5.5-7.5

Flowers

Alyssum 6.0-7.5
Aster, New England 6.0-8.0
Baby’s breath 6.0-7.0
Bachelor’s button 6.0-7.5
Bee balm 6.0-7.5
Begonia 5.5-7.0
Black-eyed Susan 5.5-7.0
Bleeding heart 6.0-7.5
Canna 6.0-8.0
Carnation 6.0-7.0
Chrysanthemum 6.0-7.5
Clematis 5.5-7.0
Coleus 6.0-7.0
Coneflower, purple 5.0-7.5
Cosmos 5.0-8.0
Crocus 6.0-8.0
Daffodil 6.0-6.5
Dahlia 6.0-7.5
Daisy, Shasta 6.0-8.0
Daylily 6.0-8.0
Delphinium 6.0-7.5
Foxglove 6.0-7.5
Geranium 6.0-8.0
Gladiolus 5.0-7.0
Hibiscus 6.0-8.0
Hollyhock 6.0-8.0
Hyacinth 6.5-7.5
Iris, blue flag 5.0-7.5
Lily-of-the-valley 4.5-6.0
Lupine 5.0-6.5
Marigold 5.5-7.5
Morning glory 6.0-7.5
Narcissus, trumpet 5.5-6.5
Nasturtium 5.5-7.5
Pansy 5.5-6.5
Peony 6.0-7.5
Petunia 5.5-6.0
Phlox, summer 6.0-8.0
Poppy, oriental 6.0-7.5
Rose, hybrid tea 5.5-7.0
Rose, rugosa 6.0-7.0
Snapdragon 5.5-7.0
Sunflower 6.0-7.5
Tulip 6.0-7.0
Zinnia 5.5-7.0

Learn more about testing your garden’s soil.

Reader Comments

Leave a Comment

Hi My garden soil is very

Hi
My garden soil is very sweet.
I want to plant Prorea plants which need a sour soil.
What can I do to change my garden soil to be sour?

Your assistance will be appreciated.

Regards
Wessie

Coffee grounds, pee on the

Coffee grounds, pee on the soil (not the plant), manure from a city horse farm would be good. Sulfer if you want to buy something.

You can use a proper mixture

You can use a proper mixture of white vinegar and water to boost the acidity of your soil or you can add pure sphagnum peat which has a very low ph. Blueberry bushes thrive in low ph and are suggested to be planted in pure peat. So this should remedy you ph issue for raspberry bushes..

Some pine needles contain a

Some pine needles contain a substance to inhibit the growth of other plants - I don't know if all do. This is an advantage to the pine tree as it stops other plants competing for nutrients wherever the chemical washes into the soil. If you have been adding pine needles over the last few years this may explain your decreasing produce.

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