I'm growing indoor basil for a science fair project to "see what fertilizer works best on indoor basil", but I can't seem to find any inexpensive organic fertilizers at stores like Home Depot or Lowe's, and I have to get my stuff from there. Also, do basil plants grow upwards or more to the sides? For the moment, I'm planning to use Miracle Gro Shake and Feed, Fertilizer Spikes, and Miracle Gro Liquid Plant food. I'm also trying to get the plants to last for at least 2 months.
Growing Indoor Basil
Certified GKH Gardening Expert
For your organic fertilizer, look for either compost or composted cow manure, or even mushroom compost. All of these should cost no more than $3-4 for a large bag and all these places should carry them. You can use them instead of potting soil for indoor plants. This are the kind of products that organic gardeners use for fertilizer. Basil will grow naturally upwards, but most people pinch their basil (https://www.gardeningknowhow.com/garden-how-to/info/pinching-plant.htm) to force it to grow outwards. You get a better harvest from the basil if it grows out rather than up. This article, if you have not read it, may also help you with growing your basil indoors: https://www.gardeningknowhow.com/edible/herbs/basil/information-on-how-to-grow-basil-indoors.htm