Choose your cooking oil base.[3] Marijuana is not water soluble. It is fat soluble meaning you need cooking oils with high fat contents. Canola oil works well. You may also choose olive or coconut oil. However, olive and coconut oils have lower boiling points than canola oil. Choose your base depending on your application. Grind your marijuana. You want to start with dry marijuana. You may choose to stick with only the flowers. Some people will use all parts of the plant. Keep in mind that you will want to strain your oil later. Try not to grind your pot so finely that it will go through your strainer. A coffee grinder or food processor will work well. Just dont turn your marijuana into powder. Mix your oil and marijuana. The strength of your cannabis cooking oil will vary by your mixture. Pour your oil into a slow cooker, double boiler, or saucepan. Add your ground marijuana and stir. Make sure all your marijuana is covered in oil.