I have had no problems with cold-damage. </p><p>The reason to use citrus-specific fertilizer is that citrus plants need micro-nutrients such as manganese, boron, magnesium and other nutrients not found in typical fertilizers. </p><p><b>Container citrus</b></p><p>If you grow non-hardy varieties, or are growing citrus in pots on a patio or balcony, you will have to fertilize more often.