How to Correctly Fertilize All Your Plants

A regular dose of important nutrients goes a long way toward better growth. Use these expert fertilizing tips for the best results.

When it comes to figuring out what to feed your plants, things can get overwhelming fast. Once you factor in the different types of fertilizers, the quality of your soil, and what each individual plant needs, it can feel easier to just skip the whole process altogether. However, if you're not fertilizing your plants, they likely won't grow as well or bloom as much as you want. Beyond sunlight and water, all plants require certain nutrients to thrive, and if you don't occasionally replenish their supply, they can end up having health issues. Here's what you need to know about fertilizing your plants to keep your garden thriving.

close up of a hand with granular plant fertilizer in a garden
A granular fertilizer sprinkled near the base of a plant will slowly release nutrients to the roots below. schulzie/Getty Images

Why Plants Need Fertilizer

Much like people, plants need a set of essential nutrients to grow properly and stay healthy. In particular, all plants must have nitrogen, phosphorous, and potassium, which are known as macronutrients because plants need them the most (there are also several micronutrients that are needed in such small quantities, you usually don't have to worry about them). Without enough of these macronutrients, you'll eventually end up with very sad plants that have weak stems, smaller leaves, fewer flowers, and poor color. The good news? You can correct most nutrient deficiencies by adding some fertilizer to your soil. The best ways to fertilize plants depends on whether they are growing in your garden or in containers.

Fertilizing Garden Plants

It might seem like your plants can get all the nutrients they need from your garden soil, but that's not always the case. Factors such as the region you're in and what had been previously growing in your soil can impact its nutrient levels. Newer properties that have had fill dirt added after construction may actually start out with very poor soil that's low in organic matter, which is the main natural source of plant nutrients. Even if you've got rich soil, your plants can use up all the available nutrients over time.

Before you begin throwing fertilizer around, you need to figure out your yard's current nutrient situation. Start by testing your soil so you know what you're working with and what you need to add for healthier plants. Skip this step and you could end up wasting money on fertilizers you don't need or overdo it and end up damaging your plants. The results of your soil test will usually tell you exactly how much fertilizer with a particular nutrient you need to provide. Because plants will use up different amounts each year, it's a good idea to do a soil test annually.

Adding compost, mulch, and other types of organic matter to your soil can help make it richer but may not provide nutrients fast enough to satisfy everything you're growing. The reason? Organic matter has to break down a little over time before plants can use the nutrients in them. As a solution, you can supplement these slowly released nutrients with more immediately available ones that fertilizers provide. Use either a liquid or granular product with a balanced amount of the big three nutrients, indicated by a 10-10-10 on the label (representing the nitrogen-phosphorus-potassium proportions in the fertilizer, often abbreviated to N-P-K), which will suit most plants.

fertilizer tab in lily plant pot
A fertilizer tab in a container will provide a steady supply of essential plant nutrients. Peter Krumhardt

Fertilizing Houseplants and Container Gardens

Fertilizer is especially important for houseplants and other container plants because they're limited to the soil in their pots. Once those nutrients are gone, your plant's roots can't stretch out to find more. This is one reason why it's important to start with quality potting soil, which often already has slow-release fertilizer mixed in to support initial growth. Once that gets used up, it's important to add more or repot the plant using a fresh mix.

If you're not sure how much fertilizer to give your potted plants, it's always better to under-fertilize than go overboard. Adding too much fertilizer can make it harder for the plant's roots to soak up water. An overdose of fertilizer can also cause leaves to turn brown or yellow, the very opposite of what you're trying to achieve. If you use a liquid fertilizer that's meant to be mixed with water first, a handy trick is to dilute it to about half the strength the label recommends. That way, you'll reduce the risk of over-fertilizing but your plants will still likely get enough of what they need (remember, a little goes a long way).

It's very important to act with care when handling and applying fertilizer. It's always a good idea to wear gloves when applying and to avoid sprinkling fertilizer when windy, as it can blow back into your face. Additionally, make sure to store the fertilizer in a safe and secure location, out of the reach of pets or children who may get into it.

How Often to Fertilize Plants

You might take daily vitamins, but plants don't need to be fertilized quite as frequently. Exactly how often you fertilize your plants depends on the types you are growing and the time of year. Some garden plants are heavy feeders (meaning they need more nutrients than others). These tend to be species that grow fast and bloom a lot, including most annuals, fruits, veggies, roses, and hydrangeas. These plants appreciate being fed about once a month during their growing season with a general-purpose liquid fertilizer. Others, including some perennials (such as bee balm and coneflower), trees, and shrubs, don't need much fertilizer at all—especially if you add plenty of compost or other organic material to their soil before planting. You may want to feed them once in the spring as they start ramping up their growth.

Many leafy and flowering houseplants also follow a seasonal schedule, slowing down their growth during the cooler months and therefore not needing as many nutrients. When they're more actively growing in the spring and summer, they benefit from a little liquid fertilizer mixed into their water about once a month. If you're not one to remember to do that, go for slow-release granules or a nutrient tab you can just push into the soil every few months or so. When it comes to indoor cacti and succulents, which generally don't need much fertilizer at all, just one or two doses of liquid fertilizer per year will suffice.

Frequently Asked Questions

  • Are fertilizer and plant food the same?

    Plant food is an informal term used for fertilizer. Both refer to a product that provides nutrients to plants to help them grow. Fertilizer can be a natural substance or synthetically created chemicals.

  • Where is the best place to buy fertilizer?

    You can buy fertilizer at a home and garden store or plant nursery. If you need to purchase it in bulk, it can be ordered online and delivered.

  • Does fertilizer go bad?

    As long as it's stored properly, fertilizer should last indefinitely. That being said, sometimes critters chew through bags, so watch for holes where they shouldn't be and consider storing fertilizer off the ground in sheds and garages. Keep it dry, too, as damp fertilizer can harden and become unusable. You should also be careful never to keep fertilizer within reach of small children or pets that may be able to access it, as it can be extremely dangerous if ingested.

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