Keeping your houseplants healthy and fertilized is easier than ever with Jobe?s? Houseplant Food Spikes. These spikes provide a continuous supply of important nutrients right at the roots where plants need it most. The pre-measured specially formulated spikes are simply inserted into the soil around your plant. Unlike liquids or granular Jobe?s Houseplant Spikes eliminate mess hazards and smells ? and can?t wash through when you water.