The Importance of the Water pH for Flowers

Nutrient Availability

• There are 16 elements required to keep a plant healthy and producing well. Many of these elements are less available in a pH that is acidic -- anything below a 6 on the pH scale. Additionally, many of the macronutrients required by plants are less available when conditions are too alkaline. Certain plant species have adapted to acidic soil and will do fine with a shortage of nutrients. Conversely, others will thrive best in pH levels above 7, and have adapted to living with a shortage of micronutrients.

Iron Chlorosis

• Chlorosis is a yellowing of leaves, iron chlorosis refers to a leaf yellowing that is present when iron is in short supply. This problem is most often caused by a pH level that is too alkaline, a common problem with overwatering or using water with an incorrect pH. Acid-loving plants, including azaleas, rhododendron and heather, are especially susceptible to iron chlorosis. Correcting the soil by adding well-decomposed compost or an iron chelate should be done as soon as possible to avoid irreversible damage.

Bacteria and Fungi

• Bacteria and fungi of all types are common parts of the environment and are prevalent in soils across the United States. The pH of soil, and of the water used for plantings, is an essential part in controlling these potentially harmful organisms. Fungi and bacteria thrive best in pH levels of 6.3 to 6.8, meaning the process of breaking down leaves, fruit and other plant parts increases at these levels. Because of the increase in population at these levels, it is important to improve pH levels as soon as possible to prevent damage or death of the plant.

Flower Color Changes

• In some plants, certain pH levels will trigger flower petals to change color. Hydrangeas, acid-loving plants, are perhaps the most common of these plants. When acidic water or soil is present, white flowers will turn blue, while alkaline water will create pink blooms. A few additions may be made to the soil to increase acid in soil, including mixing in a bit of sphagnum peat, or watering plants a few times per day with a solution of water and vinegar.