How to Use Soil pH to Get the Most from Your Organic Vegetable Garden

Soil pH is a measure of how acidic or basic your soils are. If I've already lost you, I'll sum it up in different terms: the number you get when you test your soil's pH can tell you whether your plants are likely to thrive in your garden spot or not. Luckily, if the answer is no, there are ways to change your soil's pH and make your garden into a more hospitable environment for your vegetables, flowers and lawn.

First of all, your soil is likely to be either acidic or basic, some, but not most soils have a neutral pH (7.0 for all you number crunchers out there). Most plants grow best in a slightly acidic soil environment. So, if you test your soil's pH and you get a 6 or 6.5, you're probably in good shape. As a rule of thumb, many soils in the Northeastern and Southeastern US are naturally acidic. Many soils in the Midwestern and Western US are naturally basic. These differences are due to the different parent materials (rocks, minerals, etc.) in these soils.

You can test your soil's pH yourself by using pH test strips or you can box up a sample of your garden soil and send it to your state's soil testing lab to have its pH tested. These tests are usually free or very low cost and will tell you a lot about your soil, including whether or not you need to add more nutrients (in the form of compost, organic fertilizers or other soil amendments) to it.

Soils with a pH below 5.5 or 6 can often benefit from having limestone (lime), oyster shells or other calcium-rich materials added to them. If you have your soil tested at your state's testing lab, they will provide you with a recommendation for how much lime you need to add to your garden in order to optimize your soil pH.

Soils with a pH above 7.0 are basic soils. Most crops have as difficult a time growing in basic soils as they do in acidic soils. So, if you have a basic soil, consider adding sulfur to it in order to lower your pH. Again, you will need to make sure to follow the recommendations from your soil test in order to know how much sulfur to add. Don't overdo it!

If, for whatever reason, you don't want to mess around with adding lime or sulfur to your soil, you can still grow a garden (unless your soil is extremely basic or acidic, in which case, you're going to be stuck painting it green and putting out plastic flowers if you want to have any kind of garden). Some crops, such as potatoes, sorrel and blueberries, thrive in acidic soils. So, if your soil has a pH of 5.0 and you don't want to lime it but do want to enjoy growing some of your own food, try growing these. Beets, lettuce, asparagus, spinach and broccoli are examples of crops that can be grown in slightly alkaline soils.

However, the long and short of it is that if you want to grow a variety of crops in your organic vegetable garden, you'll have to make sure that its pH is in a range that is suitable for most plants. A pH around 6.0 should suit almost any plant, except for blueberries and other acid soil-loving plants. At a pH, the nutrients in your soil will be highly available to your crops, which will help them grow better. Keeping your pH in this desirable range may require some management on your part (mostly in the form of annual soil testing and amending, if necessary) but it will be worth it.

For More Information:

How to measure your soil pH and some advice for how to amend your soil once you find out your results.


coffee plantation soil ecology and pH monitoring website-if you are a trivia or soil science buff, you're bound to enjoy this site!


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Tammy Biondi has been growing organic produce for over 10 years. Besides running Blue Horizon Farm, Tammy teaches about sustainable farming at the Central Carolina Community College. She also is a successful freelance writer, focusing on agricultural topics. Contact her at tammy@bluehorizonfarm.com.