Low pH in Soil Affecting a Carrot Plant

Carrot Identification

• Native to Afghanistan, carrots can be grown as an annual vegetable in U.S. Department of Agriculture plant hardiness zones 2 through 11. Gardeners sow them from seed a few weeks before the last frost or in early spring with a light covering of compost, then thin them to about 3 inches apart. They require consistent moisture and are usually ready for harvest 2 to 3 months later. Many different cultivars are available, but all carrots share the preference for loose, even soils, so if necessary amend the soil by working a lightener like compost into the soil before planting.

Soil pH Levels

• A measure for soil acidity and alkalinity, pH weighs heavily on whether or not a plant will have access to available nutrients and be protected from soil toxins. The pH scale ranges from 0 to 14.0, with 7.0 being neutral. Low pH levels indicate that the soil is acidic, while high pH levels mean it is alkaline. Although a few plants benefit from very acidic soils, most are happier in a slightly acidic to slightly alkaline range, with the best results between 6.0 and 6.8.

Carrots and pH

• Soil pH is also a factor in healthy carrot growth, and carrots prefer the standard range of 6.0 to 6.8. Low soil pH limits the availability of important nutrients such as phosphorous. Low pH also frees up metals such as aluminum, iron and manganese, which can be toxic to plants, and hampers the beneficial activity of microorganisms, which cannot live in such an acidic environment. If soil is too acidic, you may raise the pH by amending it with a neutralizing substance such as lime.

Changing Soil pH

• Be aware that lime does not raise pH instantaneously, but rather may take a while to produce the results you are looking for, so resist the temptation to add more than necessary. First determine your soil pH, then determine the difference between that and your ideal pH -- about 6.5. Though specific amounts of lime will depend on your garden, generally it takes more lime the lower your pH is, and more lime for clay soil than for loam, and more for loam soil than sand. To raise 100 square feet of clay soil from 5.5 to 6.5, for instance, you will need about 10 pounds of lime.