Monday, October 20, 2014

pH Can Make A Difference



Why are certain plants in the garden growing poorly while others flourish?  
Obvious answers maybe insect pests, fungal diseases and abiotic ailments such as soil deficiencies. The pH of the soil, however, is an often overlooked problem. pH measures the acidity/alkalinity of the soil. Seven is neutral; below 7 is acidic and above is alkaline.

To address this, the University of Hawaii Cooperative Extension has a publication “The pH Preference of Plants.”  The pamphlet includes a chart with many crops including fruit trees, vegetables and ornamentals, and their suggested pH growth range. All plants prefer a specific pH range, usually around neutral; some require slightly acidic while others favor slightly alkaline.

The pH of soil is important and can be a reason for poor growth. Take note which plants are doing well and which are not. Compare those plants to the list in the publication. If all or most of the poorly growing plants prefer a soil pH which is not indicative of your soil, then pH may be a problem. Get a soil analysis. Often taken through a local university cooperative extension, the analysis will be  helpful for a variety of reasons.  

As an example, breadfruit, mac nuts, parsley, lilikoi (passionfruit) and gardenias prefer an acidic soil and will grow well down to a pH of 5 and even 4.5.  These plants may be flourishing in the garden,  On the other hand, plants like bananas, mock orange, broccoli, leeks and lettuce all like a pH much higher, between 6 and 7. If these plants are growing poorly, then your soil may be too acidic.  

For additional information on pH and a useful chart, search this blog for the articles, Problems With Acidic Soils: Lime Can Work Wonders, and Unsuspected Causes of Plant Damage.