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PH Meter

Soil PH for Container Gardens

If you want beautiful healthy plants that produce lots of big fruit you need to understand soil PH.

What is PH?

To understand how PH levels effect the soil lets first talk about what ph is and does.

PH is the common abbreviation of Potential Hydrogen. The PH scale is a scale that is used to determine the relative basicity and acidity of a substance. This scale shows the relative hydrogen ion in the substance.

On the PH scale a reading of 7 is considered neutral. This means that the substance is neither an acid or a base.

If you want a more scientific discussion on the topic there is a really good explanation of PH on science

So what does all this mean for a gardener?

PH scale reading is vital to gardeners.  PH levels will determine the nutrients available to the plants.

PH itself is not a nutrient.  It is a catalyst which helps release the nutrients for use.

It  means that whatever nutrients are in the soil are more readily available to your plant.

This chart gives you a general idea at what PH level specific nutrients are more easily released.

The roots of your plant are designed to absorb nutrients from the soil. They can only preform this function is the soil is the right PH to release those nutrients.

Proper PH does not mean great soil!

It is important to remember that Soil PH levels are important but they alone do not indicate good soil.

For example builder’s sand has a 7.0 PH or neutral PH but it has not nutrients at all.  Whereas compost came have any PH level from very from 1 to 14.  Note that most fully mature compost does typically fall in the 7 range.

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When you have the proper PH level and the right nutrients this will created a perfect growing environment for your plants.

How to test your PH levels

The best PH level for most vegetable gardens is 6.0 to 7.0. Check your favorite vegetables to determine the exact number for they.

Testing the soil PH is super easy. There are many different types and brands of soil ph testers on the market. A simple tester will cost you about $9. You can get very accurate high end digital testers for as much as $100.

Common meter

The method of testing is as simple as putting the probes into the soil and reading the display.


You can also get an accurate test for PH levels as well as other soil conditions from your local state university. Most state university systems offer free soil testing. Contact the university to find out the details.

Practical guide

Now that you understand the basics of garden soil PH how can you use the information to grow the best vegetables.


First, check your PH levels.

If the levels are not correct there are easy ways to get the back in line.

How to lower soil PH in container gardens

If you test your soil and find that it has a PH level that is too high there are a couple of ways to help the soil become more acidic.

Use lemon juice

Using a small amount of lemon juice, 2 tablespoons per gallon of water, can help bring the PH level down in container plants.

When you use lemon juice remember that too much of a good thing is very bad. Don’t get lemon juice directly on the leaves because it can burn them.

Also add lemon water only once a week until the soil PH levels are good. Don’t try to make drastic changes with one watering.

Add coffee ground

Coffee grounds will raise the acidity levels in your soil. It will also add many needed nutrients and elements such as magnesium, nitrogen , potassium, phosphorus and Cooper.  Un brewed coffee is best.  Brewed coffee ground tend to be closer to neutral

Just lightly top dress the container with coffee grounds than water as normal. Until you soil PH comes into the right levels it would be a great idea to recycle your daily coffee grounds by adding them when you water each day.

This method will slowly raise the PH level. This is the best way because it will not shock the plant.

However if you have very low levels you may want to raise the level faster.


How to raise soil PH in container gardens

If your container soil test on the high side of the PH scale you can correct that situation by one of these methods.

Add baking soda

To raise PH levels in your container garden naturally use baking soda.

Add 1 tablespoon per gallon of water and use the mixture to water once a week.

This will raise the PH slowly which is the safest way to insure you will not shock your plants.

Use limestone to raise soil PH

You can you limestone to raise the PH levels more quickly. This is commonly sold as Lime dust in garden shops and hardware stores.

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Use limestone with some caution in containers. A little will go along way and too much can easily damage or kill your plants. Add a tablespoon to a gallon of water. Use to give the plants a light watering.

Retest and use again as needed.

Summing up the important points of soil PH

  1. Test your soil with a PH meter
  2. Adjust the PH slowly if possible
  3. Use lemon juice or coffee grounds if levels are too high
  4. Use baking soda or limestone if the soil levels are too low
    Retest regularly to stop a problem before it becomes critical
    For information on container soil visit “soil do’s and don’t “




This Post Has 4 Comments

  1. Tour summary controdicrs your blog. Adding sulfer will be ot raise the ph level will lower the ph level. Either I am reading it wrong or you are explaining it incorrectly.
    A high bbn ph level is alkaline and low ph level is acid…..

  2. I think for sulphur, you mean to say that it will lower the PH, not raise. Sulphur makes soil more acidic (PH7)

    1. Hi Jay. Thank you! you are right. I updated the post. Thank you for reading and pointing out my error. My goal is to have the most accurate information available

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