5 Common Fertilizing Mistakes You Want to Avoid

Written by Naomi Meza


Posted on June 20 2019

Applying fertilizer to your garden is an essential step in guaranteeing a healthy harvest, but you do need to be strategic with your application.

While there are a number of times when fertilizing your plants is a great idea, contrastingly, there are just as many moments when the fertilizer bag should stay closed.

We’ve rounded up a few common mistakes gardeners are likely to make when fertilizing their plants.

You’ll want to keep these errors in mind, so you can keep your plants at their best and prevent any garden mishaps that may come from a lack of knowledge in the fertilizer department.

1. Overfertilizing

Overfertilizing Your Plants

In many cases too much of a good thing is bad and this remains true with fertilizer.

While you may think providing your plants with frequent feedings and in large quantities is beneficial, it is possible to overfertilize and this can be detrimental to the health of your garden.

Plants need a well-balanced ration of nutrients and when these levels are off, you may notice your plants appear sickly.

With over fertilizing, your plants may show the following symptoms:

  •  Slow to mature
  • Tall plants with weak stems
  • Chlorosis, or paling, yellow discoloration on leaves
  • Lesions on the roots and stems
  • Leaves falling prematurely
  • Reduced root growth


Once your plants exhibit signs of fertilizer toxicity, there is no way to reverse it. All you can do is water them down thoroughly to ensure any excess fertilizer is washed away.

To completely avoid overfertilization, it’s important to stick to the fertilizer manufacturer’s guidelines both in terms of application rate and frequency of application.


2. Underfertilizing

Underfertilizing plants

On the other hand, it is also possible to under fertilize your plants. In an ideal world, we wouldn’t need fertilizer because our soils would be perfect in terms of nutrient availability and texture.  

But sadly, this is not the case. Fertilizing your plants is a must if you have less than ideal soil conditions and you may not be applying enough if your soil is extremely nutrient deficient.

Symptoms of under fertilization include the following:

  • Chlorosis
  • Generalized symptoms as opposed to localized
  • Stunted growth
  • Leaves turning purple or reddish
  • Interveinal chlorosis, or chlorosis between leaf veins while veins remain green
  • Necrosis, or dying plant tissue


There’s a fine line between over and under fertilization that is hard to maintain, but once you determine what levels work for your garden while staying within the manufacturer’s recommendations, under and over fertilizing your plants will no longer be a worry.


 3. Only Considering NPK

Organic Blood Meal 13-0-0

A lot of emphasis is placed on NPK in the gardening world. NPK stands for the Nitrogen, Phosphorus and Potassium content in a bag of fertilizer.

These nutrients are represented by three numbers, typically on the front of the fertilizer product and while they are essential to the fertilizing process, they don’t always tell the whole story.

NPK are macronutrients, meaning your plants need each of these three nutrients in large amounts compared to secondary nutrients like calcium or micronutrients like zinc.

It can be intimidating especially for new gardeners, to know exactly what to look for in a fertilizer, but one thing we want to suggest is looking beyond the NPK when selecting fertilizer.

You also want to pay attention to the micro and secondary nutrient content as well as the form of fertilizer itself (i.e. liquid, powder, granular, etc.). Other factors to consider are whether the fertilizer is slow release, heavy metal free and encourage microorganisms in the soil.


4. The Wrong Fertilizer

Organic water soluble fertilizer

Again, selecting the right fertilizer for your plants is essential to their health. The balance between nutrients in your garden is delicate.

In fact, it’s so delicate, that having higher amounts of one nutrient will not only result in overfertilization but can potentially result in limited availability of other nutrients in the soil.

In this case, your plants will become nutrient deficient because one nutrient that is available in a larger quantity is blocking the intake of other key nutrients.

The easiest way to prevent this is by conducting a soil test either before planting or at the first sign of a nutrient deficiency to determine what your plants truly need.


5. Poorly Timed Fertilizer Application

Fertilizing plants

Knowing when to apply fertilizer to your plants is of utmost importance because plants need different amounts of fertilizers in various growth stages of their life cycle.

Generally speaking, you want to apply your fertilizer at least 2 to 3 weeks before planting, especially if you are using organic, slow release fertilizers to allow enough time for the nutrients to break down and become available in the soil.

On a similar note, you want to become familiar with the crop you are growing so you’ll know when to apply fertilizer during its growth and blooming stages.

Applying fertilizer outside of critical time frames of growth in your plant, can reduce fertilizer effectiveness and crop yield.

Keeping these five common mistakes in mind will allow you to avoid pitfalls that are easily preventable. Shop some of our fertilizers below - practice makes perfect!


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  • Comment author

    Thanks for warning me that overfertilizing my garden can affect its health negatively. I’m trying to grow some spinach and potatoes in my garden and I want them to grow up healthy so I can start adding more crops. It might be a good idea to consult a professional about the subsurface injection fertilizer system and see if installing it will benefit my garden.
    Posted by Zoe Campos | August 24, 2020
  • Comment author

    Justus: Hello, thank you for your question! We would recommend that you determine which issue is more urgent for you to resolve: feeding your plant or ridding of the insects. Based on this, apply one product first and wait at least 2 weeks before applying the second product. If you have any other questions, please email our customer service team via the address provided in our “Contact Us” page. Thank you!

    Posted by Greenway Biotech | April 24, 2020
  • Comment author

    Is it right to apply fertilizer and insecticide control on trees at the same time? Kindly assist.

    Posted by Justus | April 24, 2020
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