What Is the Purpose of Plant Food?

Why Use Plant Food?

• When plants go dormant or exit their growing season in the winter, they don't need much food. They use nutrient reserves in the roots to stay alive in the colder months. As they start to bud and grow, they use up the rest of those reserves to put out new leaves that can start absorbing sunlight. Without another influx of food for the roots, the plants have trouble growing and building up new reserves for the next winter.

Nutrients

• Fertilizer typically offers three main nutrients to plants: nitrogen, phosphorous and potassium. These help support leaf growth, leaf color, bloom growth and fruit development. In smaller amounts, plants also need additional nutrients such as calcium, sulfur, iron and magnesium, which are included in most plant foods. Plant food comes with different levels of these nutrients, so check the labels for a list of what plants the food is designed for.

Signs of Not Enough Food

• When plants are several years old, they don't need as much fertilizer as newer plants. Young plants thrive when fed properly. Without enough food, plants tend to exhibit stunted growth compared to their potential heights and fewer leaves than normal. The leaves might also be yellow, or green with areas of yellow. The leaves can fall off, further damaging the plant by not allowing it to garner nutrients from the sun. If you notice any of these symptoms, it's time to feed your plant.

When to Feed

• Each plant has different nutrition needs, but they all need fertilizer in the spring after depleting their winter reserves. Some also do well with a shot of plant food early in the fall, as they begin storing up reserves for the next winter. Vegetables and plants that bloom all summer often need more fertilizer than other plants, often every four to six weeks. Overfertilization can cause some of the same symptoms as a lack of food, or it can stimulate growth so much that the plant doesn't enter its normal dormancy phase. This can cause the plant to die when the first frost hits. Follow the fertilizer label's instructions to help you determine when, besides spring, your plants need to eat.