From time to time, you may find an unwanted visitor has had a field day on your crop. Indoors, this is much less common than an outdoor operation, but is still a possibility. Most pests and deficiencies can be avoided by keeping a clean and tidy grow room, the correct environment, and with the use of some additives. Sometimes, however, you may fall victim to an infestation of thrips or find yourself with a touch of powdery mildew. In this case a more definite solution is necessary. There are a vast range of pesticides and deficiency products on the market to help with this.