The bright, lip-puckering sourness of lemons? That’s the result of acid. So is the cutting tang of vinegar and the slightly sharp flavor of soda. In each case, your tongue is detecting an abundance of hydrogen ions (H+) in the food. The more hydrogen ions, the greater the acidity.
Although our tongues can detect broad differences in the acidity of certain foods, we can discuss acidity more qualitatively (and in things we wouldn’t want to eat such as soil!) using the pH scale. Completely pure water, which has a pH of 7, has no excess H+ ions and is considered neutral. As the pH gets lower, the acidity increases. Something with a pH of 1 has 100,000 times the concentration of H+ ions as something with a pH of 6!
These dramatic variations in H+ concentration can have profound effects on the surrounding chemistry. In the case of soil, increased acidity also affects which vegetables can successfully grow.
Impact of Acidic Soil on Vegetable Plants
Acidity can have a number of different impacts on growing plants. At extremely low pHs (<4) the hydrogen atoms themselves actually damage the roots of plants, making it hard for virtually any plants to survive.
Even at more moderate acidity levels, the presence of excess hydrogen ions still has an impact. For example, acidity can tie up key nutrients like nitrogen, phosphorus and potassium, making them less available for absorption through the roots. It also can increase the concentration of dissolved metals, like aluminum, iron and manganese, which can be toxic to plants. For instance, aluminum can inhibit root growth, while excess manganese is apparent in crinkling and cupping of leaves. Heavy metals (like lead) also have increased solubility at lower pH levels.
Best Vegetables for Acidic Soil
Acidic soil is common and has many different causes. Things such as excessive rainfall, weathering of ground minerals, fertilizer use, bacterial activity and contamination all can contribute to lower ground pH values. And while many people assume that blueberries and cranberries are the only crops suitable for acidic conditions, there are actually several vegetable plants that can tolerate mild to moderate acidity:*
Vegetables for Somewhat Acidic Soil (pH = 5.5 – 6.5)
1. Carrot (5.5-7.0)
2. Cauliflower (5.5-7.5)
3. Corn (5.5-7.5.)
4. Cucumber (5.5-7.0)
5. Eggplant (5.5-6.5)
6. Garlic (5.5-7.5)
7. Pepper (5.5-7.0)
8. Pumpkin (6.0-6.5)
9. Radish (6.0-7.0)
10. Rhubarb (5.5-7.0)
11. Sorrel (5.5-6.0)
12. Squash, winter (5.5-7.0)
13. Tomato (5.5-7.5)
14. Turnip (5.5-7.0)
Vegetables for Moderately Acidic Soil (pH = 4 – 5.5)
15. Peanut (5.0-7.5)
16. Potato (4.5-6.0)
17. Sweet potato (5.5-6.0)
Acidic soil doesn’t have to be a death knell for your garden. By identifying the pH of your soil using simple equipment, such as litmus paper or inexpensive soil meters, it’s possible to plan appropriate crops for different areas and not let acidity sour your gardening experience.
Which vegetables do you grow in acidic soil? What advice would you add? Share your thoughts in the section below: