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Understanding Soil pH

The pH of soil refers to the measured level of acidity or alkalinity in your soil.

The pH scale ranges from 1.0 up to 14.0 with 7.0 being neutral.

If soil pH is higher than 7.0 it is alkaline.

If the soil is lower than 7.0 it is acidic.

It is important to know your soil PH because it can have a great effect on which nutrients are available to your plants. When the pH is too high or too low, your plants may get too much of some nutrients and not enough of others.

Testing Soil pH

Checking your soil pH is fairly easy. Do-it-yourself soil-testing kits are available here.

It only takes a minute to get your pH reading and the testers can be used over and over.

It is very important to take samples from different sites in your gardens and beds. pH can vary even within a small area.

Adjusting Soil pH

If your pH test shows your soil to be between 6.0 and 7.0 you do not need to adjust the pH, it is perfectly fine for most plants.

For pH below 6.0 (acidic soil)

For low pH readings you need to add lime to your soil. Garden lime (calcium carbonate) is readily available at garden centers hardware stores and home-and-garden stores.

Applying about 5 to 10 pounds of garden lime for every 100 square feet of garden area will raise the soil pH by one full number (from 5.0 to 6.0, for instance).

Add the right amount based on your initial soil pH reading and work it into the top few inches of soil.

You can apply the lime at any time of the year but it’s best to add several month before planting.

Thereafter you should test pH yearly and adjust as necessary.

For pH above 7.0 (alkaline soil)

To lower pH you have your choice of soil additives – ground sulfur, calcium sulfate, iron sulfate, aluminum sulfate, or garden gypsum. These are all readily available at garden centers hardware stores and home-and-garden stores.

Apply them according to the package instructions (each will be different), depending on how much you need to lower your soil pH.

Thereafter you should test pH yearly and adjust as necessary.

Read the next Article: Greenhouse Growing- Plant Care

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Gardening Tip of the Day

  • If the best looking melons in the garden had little or no flavor last summer, the problem may be the variety planted. Some melon types do better in a region than others and only trial and error or an experienced local gardener or county extension agent can guide you.

    Occasionally the problem is the soil. It may lack sufficient nutrients or the pH can be too low. Dig in compost or rotted manure before planting. Melons do best in neutral to slightly alkaline soil. Have your soil tested and if the pH is below 6.5, amend with lime. Sometimes a lot of rain near the time of harvest will dilute the sugar in melons affecting taste. Watermelons will regain their sugars if you hold off harvesting for a few days. Cantaloupes will not.