All plants can benefit from some fertiliser. It’s important you choose the right kind, for example, if a plant needs a fertilised with a lot of potassium, then this needs to be an important consideration. A little research will tell you what your plants need and what you can do to make sure that they thrive. If you are growing chilli plants or plants with fruit/seeds, then you can often buy particular types of plant food and fertiliser that will be perfect for them. This will help them grow strong and healthy, and to produce as much fruit as possible for you.
Many plants that you grow indoors will also need to have some additional fertiliser in order to grow strong and healthy. You can buy plant fertiliser for houseplants, as well as for outdoor plants, that will have the right balance of nutrients for the particular plants you are growing.