What exactly is plant fertilizer?
Fertilizer is a broad name for any kind of concentrated nutrient source that is designed to be 'fed' to plants in order to support healthy, successful growth. They can come in a number of different forms such as sticks, pellets, powders and granules, but Planta typically recommends using liquid fertilizer.
These nutrients are provided in chemical (inorganic) or organic form and are based on the three major nutrients that plants need: Nitrogen, Phosphorus and Potassium. You may have heard this referred to as the N:P:K ratio - different plant types require varying ratios based on their individual needs.
Nitrogen, Phosphorus and Potassium are known as macronutrients, referring to the fact that they are needed in large amounts for plants to be able to survive. Micronutrients, on the other hand, are required in significantly smaller quantities when compared to macronutrients.
Why should you fertilize your plants?
Just like humans, plants benefit from a healthy, nutritious diet. However, most typical gardening soils do not contain sufficient nutrients for your plants, which is where fertilizer comes in.
Fertilizers provide the nutrients plants need in order to grow faster, bigger, stronger and, where applicable, to produce more fruits and / or flowers. Healthier plants are less susceptible to developing diseases or pest infestations and will also typically live longer than their under-fertilized counterparts.
However, it should be noted that too much fertilizer can also be a bad thing, in a similar way to how we humans shouldn't take too many multivitamins! It's important to find a good balance and get to know your plants so you recognize what their normal, happy state is so that you'll soon notice if any symptoms of an imbalance start to crop up.
How do fertilizers work?
Nutrients such as Nitrogen are present in the air around plants but are not available to them, despite the fact that they are necessary for survival. Fertilizers provide available nutrients so that your plant can succeed even in an 'artificial' (indoor) environment where it would otherwise struggle to find a source of those nutrients.
The source of them in fertilizers depends on whether they're organic or inorganic. Inorganic fertilizers are artificial, synthesized forms of nutrients, although sometimes they're also derived through mining. Organic fertilizers include seaweed, bonemeal, poultry manure and fish blood.
Macronutrients (Nitrogen, Phosphorus and Potassium) are the essential building blocks that allow your plant to be able to grow, and so they make up the bulk of all fertilizers. There are also secondary macronutrients which are also integral to maintaining plant health, referred to as secondary only because they are required in lesser amounts. These include Calcium, which aids nutrient absorption and disease resistance, Sulfur, which can help improve hardiness, and Magnesium, which is a necessary component (along with Phosphorus) of photosynthesis.
Nitrogen contributes to new green growth and leaf production, Phosphorus promotes root growth (as well as new shoots) and Potassium assists the production of fruits and flowers. For plants that don't produce fruits or flowers, Potassium can still be helpful in that it supports overall plant strength.
Micronutrients - also necessary but in much lower quantities - include Zinc, Iron, Copper and Manganese, among others.