What’s the Best Soil pH for Your Plants?

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Learn Why Soil pH Matters—and How to Get It Just Right

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Soil pH might not be something you think about often—but it plays a big role in how well your garden grows. In fact, no matter how much fertilizer you add, your plants can’t use it properly if the pH is off.

Most garden plants like soil that’s slightly acidic to neutral, in the range of 6.0 to 7.0, but some plants are pickier than others. Blueberries, for example, like it much more acidic, while asparagus prefers a pH on the alkaline side.

Use the soil pH chart below to figure out what level your plants like best. Then, find out how to test your soil and adjust it, if needed, to keep your garden growing strong.

What Is Soil pH?

Soil pH measures how acidic or alkaline your soil is, on a scale of 0 to 14.

  • A lower number (below 7) means acidic soil, sometimes called “sour.”
  • A higher number (above 7) means alkaline, or “sweet.”
  • A pH of 7 is neutral.

A pH of around 6.5 works well for most garden plants. But some crops and ornamentals prefer things a little more acidic or alkaline. For instance, hydrangeas change flower color depending on soil pH—blue in acidic soil and pink in alkaline.

More importantly, the pH affects how plants take in nutrients. If the pH is too high or too low, those nutrients just sit there—even if you’ve added compost or organic fertilizer to the soil. The roots simply can’t absorb them.

Here’s a quick look at the pH ranges some common plants prefer. (See full table below.)
 

PlantIdeal pH Range
Blueberries4.5–5.5
Tomatoes6.0–6.8
Lettuce6.0–7.0
Carrots6.0–6.8
Hydrangeas5.2–6.2 (for blue)
Asparagus6.5–7.5
Roses6.0–6.5

How to Test Your Soil pH

There are two main ways to check your soil’s pH:

  1. Use a test kit – Sold at garden centers and online, these are easy to use and give a general idea of your pH.
  2. Send a sample to your local Cooperative Extension office – Many states offer soil testing for a more detailed picture, including nutrient levels and recommendations for improving your soil. Find your Cooperative Extension.

Tip: Test different parts of your garden, especially if you grow different kinds of plants. Soil can vary from bed to bed.

How to Change Soil pH

Once you know your soil’s pH, you can add natural amendments to raise or lower it, depending on your plants’ needs.

If your soil is too acidic (below 6.0):

Add ground limestone, wood ash, or crushed oyster shells to bring the pH up.

If your soil is too alkaline (above 7.5):

Use elemental sulfur, gypsum, peat moss, or compost to bring it down.

Tip: Organic matter like compost is always a good bet—it helps buffer pH and improves the soil overall. Just take it slow and retest your soil after a few months. Changes don’t happen overnight.

Keep It Balanced

Soil pH doesn’t have to be perfect—but it should be in the ballpark. Here are a few last tips:

  • Don’t overcorrect. Make small changes and retest.
  • Add compost regularly. It naturally balances pH and improves structure.
  • Watch your plants. Yellowing leaves or slow growth might mean your pH is off.
  • Rotate crops to help avoid long-term imbalances. See our Vegetable Planting Calendar to plan ahead.

Chart: Optimum Soil pH Levels for Plants

Common NameOptimum pH Range
Apple5.0-6.5
Ash6.0-7.5
Azalea4.5-6.0
Basswood6.0-7.5
Beautyberry Shrub6.0-7.5
Birch5.0-6.5
Blackberry5.0-6.0
Blueberry4.0-6.0
Boxwood6.0-7.5
Cherry, sour6.0-7.0
Chestnut5.0-6.5
Crab apple6.0-7.5
Dogwood5.0-7.0
Elder, box6.0-8.0
Fir, balsam5.0-6.0
Fir, Douglas6.0-7.0
Hemlock5.0-6.0
Hydrangea, blue-flowered4.0-5.0
Hydrangea, pink-flowered6.0-7.0
Juniper5.0-6.0
Laurel, mountain4.5-6.0
Lemon6.0-7.5
Lilac6.0-7.5
Maple, sugar6.0-7.5
Oak, white5.0-6.5
Orange6.0-7.5
Peach6.0-7.0
Pear6.0-7.5
Pecan6.4-8.0
Pine, red5.0-6.0
Pine, white4.5-6.0
Plum6.0-8.0
Raspberry, red5.5-7.0
Rhododendron4.5-6.0
Spruce5.0-6.0
Walnut, black6.0-8.0
Willow6.0-8.0
Asparagus6.0-8.0
Bean, pole6.0-7.5
Beet6.0-7.5
Broccoli6.0-7.0
Brussels sprout6.0-7.5
Cabbage6.0-7.0
Carrot5.5-7.0
Cauliflower5.5-7.5
Celery5.8-7.0
Chive6.0-7.0
Cucumber5.5-7.0
Garlic5.5-8.0
Kale6.0-7.5
Lettuce6.0-7.0
Pea, sweet6.0-7.5
Pepper, sweet5.5-7.0
Potato4.8-6.5
Pumpkin5.5-7.5
Radish6.0-7.0
Spinach6.0-7.5
Squash, crookneck6.0-7.5
Squash, Hubbard5.5-7.0
Tomato5.5-7.5
Alyssum6.0-7.5
Aster, New England6.0-8.0
Baby’s breath6.0-7.0
Bachelor’s button6.0-7.5
Bee balm6.0-7.5
Begonia5.5-7.0
Black-eyed Susan5.5-7.0
Bleeding heart6.0-7.5
Canna6.0-8.0
Carnation6.0-7.0
Chrysanthemum6.0-7.5
Clematis5.5-7.0
Coleus6.0-7.0
Coneflower, purple5.0-7.5
Cosmos5.0-8.0
Crocus6.0-8.0
Daffodil6.0-6.5
Dahlia6.0-7.5
Daisy, Shasta6.0-8.0
Daylily6.0-8.0
Delphinium6.0-7.5
Foxglove6.0-7.5
Geranium6.0-8.0
Gladiolus5.0-7.0
Hibiscus6.0-8.0
Hollyhock6.0-8.0
Hyacinth6.5-7.5
Iris, blue flag5.0-7.5
Lily-of-the-valley4.5-6.0
Lupine5.0-6.5
Marigold5.5-7.5
Morning glory6.0-7.5
Narcissus, trumpet5.5-6.5
Nasturtium5.5-7.5
Pansy5.5-6.5
Peony6.0-7.5
Petunia5.5-6.0
Phlox, summer6.0-8.0
Poppy, oriental6.0-7.5
Rose, hybrid tea5.5-7.0
Rose, rugosa6.0-7.0
Snapdragon5.5-7.0
Sunflower6.0-7.5
Tulip6.0-7.0
Zinnia5.5-7.0

Garden Soil pH FAQs

Q: Can I test soil pH with vinegar and baking soda?
A: Sort of. Vinegar will fizz in alkaline soil; baking soda will fizz in acidic soil. It’s a fun trick, but not very precise. For best results, use a real soil test.

Q: How long does it take to change soil pH?
A: It depends on your soil type. Sandy soil changes faster; clay takes longer. Plan on checking again after 3 to 6 months.

Q: Does compost make soil more acidic or alkaline?
A: Most compost brings soil pH closer to neutral. That’s one reason it’s great for general use.

About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
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