pH for common garden veggies and second-season crops

pH for common garden veggies and second-season crops

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Potatoes need a very acidic soil to thrive, making Long Island an ideal environment. Photo by Ellen Barcel

By Ellen Barcel

What exactly is soil pH and how does it affect your ability to grow the veggies you want? Well, it’s a measure of how acid or alkaline soil is. On a scale of 0 to 14, seven is neutral. Below 7 is acidic (sour) and above 7 is alkaline (sweet). Today, we have little kits that can be used to test soil available in garden stores, but in the “olden days” farmers tasted the soil, hence the terms sour for acidic and sweet for alkaline soil.

The soil pH affects how different plants take up nutrients. Some do better in an acidic soil, that is, take up nutrients better, while others do better in a neutral or slightly alkaline soil.

Long Island soil, for the most part, is very acidic. Test your soil and treat it accordingly based on what you want to grow. Oregon State University Extension explains it this way. Each unit of change is a 10-fold difference. Going from 6.0 to 5.0 means that the soil is 10 times more acidic, so it’s a very big change.

Potatoes do well in a soil pH that is very acidic ­— 4.8 to 5.5. This is why Long Island, going back to the early 1800s, has been known for its potato farms. Farmers had one less thing to be concerned with, namely changing the soil pH. Cornell University notes that growing potatoes in a pH of 6.0 or higher makes them more prone to scab (a disease of root and tuber crops).

Veggies that do extremely well in acidic soil (going down to the 5.0 range) include artichoke, beets, cabbage, sweet potatoes, turnips, leek, chives, carrots, radishes, cucumbers and chili peppers.

Veggies that do well in acidic soil (say 5.5) to neutral (7) include beans, broccoli and cauliflower. Bush beans are ideal as they require no staking. Summer squash, which matures in 50 to 60 days, also does well in acidic soil. Tomatoes also do well in this broad range of soil pHs as well as cucumbers.

Plants that do well in neutral (or only slightly acidic) to mildly alkaline range (7.0 to 8.0) are mushrooms, okra, parsley, peppers, yams and asparagus.

If your soil is substantially below the optimal range for what you are growing, add lime, following manufacturer’s directions. Remember that lime can take many months or even a year to break down in the soil. Read the package directions on the various types you are considering. It’s probably best to start adding the lime to the soil now in the areas where you are planning to grow veggies next year. Also remember that the soil will revert to the pH it tends to be naturally, so once you start liming the soil to reach a certain number, you need to continue to do that as per package directions each growing season.

Ellen Barcel is a freelance writer and master gardener. Send your gardening questions and/or comments to [email protected]. To reach Cornell Cooperative Extension and its Master Gardener program, call 631-727-7850.