Understanding Soil pH

Soil pH can be a critical factor in your gardening success. Some plants thrive in neutral soil while other plants such as azaleas and rhododendrons prefer a more acidic environment. The difference lies in the plant’s ability to use nutrients present in the soil. For plants that prefer a more acidic soil, a critical nutrient is iron. Iron is most available in soil with a pH of around 5.5. Without iron these plants will turn yellow and suffer stunted growth.

Lowering soil pH is not difficult. In new plantings, work-in organic matter such as peat moss or compost.

For existing plantings, regular feeding with Holly-tone will keep soil at an optimum pH while providing all the major, minor, and trace nutrients plants require.

A partial list of plants preferring acidic soil includes:

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Care sheet
By far the most popular acid-loving plants are azalea, holly, and rhododendrons. If planted and cared for properly, these plants will delight the gardener for years. Choose plants from your local garden center that appear robust, with good green color.

Planting
When planting, a hole should be made roughly twice as large and twice as deep as the root ball. One third of the soil removed should be replaced with compost, peat moss or other good humus. To this, one cup of Holly-tone per 2-1/2 gallon bucket of soil should be added and thoroughly mixed. There should be enough of this mixture in the hole to allow the new plant to sit at the same depth it was previously growing. The soil mark on the trunk can be used as a guide. The bottom of the hole should be packed firmly to prevent later settling. Once the plant is placed in the hole and filled half full with the soil mixture, it should be packed firmly, soaked with water, and allowed to settle. After the hole is completely filled, the top two inches should be left loose for easy absorption of water. A slight depression around the plant will also help conserve water. Adding mulch will also help conserve water, slow down evaporation, and control weeds.Often, plants will be purchased in plastic containers. When removing the pot, inspect the root mass. It is not unusual for the roots to have grown in a circular pattern around the inside of the container. If this is noticed, the roots should be disturbed SLIGHTLY to encourage new growth. Simply score the outside of the root mass with a knife to break the circular pattern.

Feeding
Feed azaleas, rhododendrons, and holly in the spring with Holly-tone. In general, the proper rate of application is one cup of Holly-tone per foot of branch spread. This rate should be doubled for plants over three feet wide. Do not work the plant food into the soil as these plants have surface root systems that can be disturbed by such activity. It is best to apply the Holly-tone directly to the soil prior to mulching. If this is not possible, Holly-tone can be applied on top of mulch at double the standard rate. This will compensate for the loss of nutrients in the mulch layer.A second half-strength feeding of Hollytone is recommended in late fall. This will help harden off new growth, aid in root development, and enable the roots to store food for use in early spring.

Pruning
Azaleas and rhododendrons both begin to form their blooms for the next spring season in the late spring or early summer. Because of this bloom set it is critical that these plants be shaped or pruned immediately after the current year’s bloom.