Plants do need nutrients, but they don't necessarily need fertilizer.
Plants use their leaves to make food from sunlight, water, carbon dioxide and nutrients.
Nutrients in the soil are necessary for structure, regulating metabolism, growth and reproduction. Some key nutrients for plants include nitrogen, phosphorus, potassium, calcium, zinc, magnesium, iron and manganese. If a plant is appropriate for the soil and site where it is located, it may not require additional nutrients from fertilization. A great way to improve your soil is by adding compost, which can be made from partially decomposed yard or kitchen waste. When added to your soil it can create the perfect medium for sustained plant health.