GH Armor Si Armor Si™ is suitable for all types of plants during all stages of growth. It can be used for plants growing in hydroponics, coco coir and all types of media. Use as a growth enhancer with irrigation water, or in addition to your regular fertilizers. Armor Si™ improves plant structure and foliar development, increases yield and improves flower and fruit production. In addition, your plants will experience improved heat and cold tolerance, stress resistance and light absorption, which leads to greater plant stature.