Greenhouse - High pH Sensitive Bedding Plants

Certain bedding plants are sensitive to high pH in growth media and can show iron deficiencies when pH is elevated. The following is a short article on the subject.

It is important to monitor the pH of your media on a regular basis. The group of plants labeled the “iron-inefficient” are prone to iron deficiency if the pH goes above 6.2. This group includes torenia, bacopa, calibrachoa, diascia, nemesia, pansy, petunia, snapdragon and vinca. These plants are best grown at a pH range of 5.4 – 6.2 to increase solubility of micronutrients. This group is often misdiagnosed as a high feed or high iron group. They do not necessarily require higher rates of fertilizer or iron, but they are especially sensitive to high pH and need adequate iron.

Extracted and adapted from the March 31, 2006 edition of the Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension.