Ericaceous plant food is designed for plants that thrive in acidic soil. Plants like azaleas or rhododendrons will not do well if the soil is not acidic. Soil can be altered to meet the needs of these plants with the use of commercial fertilisers that is mixed in with the soil. Ericaceous plant food can also be used for plants that don't grow well in soil with high lime content.
Ericaceous plant food or compost will alter the pH balance of the soil. For acid-loving plants to do well, the pH level of the soil needs to be less than 7--a pH balance of 7 is considered neutral. Most acidic plants will thrive in soil that has a pH balance of 4 or 5. Soil can be tested to determine the current pH level with a soil testing kit, which can be purchased at most gardening centres. It is advisable to retest the soil after the ericaceous plant food has been added.
Plants that do poorly in lime or chalky soil are called calcifuges plants and can benefit from ericaceous plant food, as well. Lime and other alkaline in the soil will turn the leaves of these plants yellow, and if the soil is left untreated, the plant will eventually die. If soil isn't tested regularly with a soil test kit to check the pH level, the plant will show signs of when the acidic level of soil is decreasing and more ericaceous plant food is needed.
Ericaceous plant food contains key elements to alter the soil for acidic plants. As the ericaceous plant food lowers the pH balance of the soil, iron becomes more easily absorbed by acidic plants. As acidic plants have high iron requirements, these plants thrive as more iron becomes available. The usable forms of calcium become less available to plants in acidic soil. However, acidic plants have the ability to improve calcium absorption and are not affected.
As pH level of soil is altered by ericaceous plant food the toxicity level of manganese in the soil increases. For many plant families the toxicity would be at fatal levels and the plants would die. Acidic plants are able to reduce the effects of toxic manganese levels by concealing excess absorbed magnesium in the compartments of the leaf. However, if the plant food has altered the soil to much the plant will absorb too much manganese, which will result in an iron deficiency in the plant.
Acidic Plants Only
Soil that has been amended with ericaceous plant food should have only acidic plants placed in it. Because ericaceous plant food alters the pH balance of the soil so significantly, it is advised that acidic plants be kept separate. It is also important to remember that while it is possible to change the soil back to a neutral or non-acidic state, it will require time. When planning an acidic flower bed, the future planting goals of the flowerbed should be considered.