6 Signs You Are Over Fertilizing Your Plants

“If a little is great, and a lot is better, then way too much is just about right!”

When it comes to fertilizing plants Mae West’s advice can be deadly. Plants receiving the proper amount of fertilizer respond quickly in growth and look great. The result makes it temping to give them more fertilizer (in dose, frequency or both) and often this is a mistake. Below are six signs you can easily recognize to determine if you are giving your plants too much fertilizer:


  1. Yellowing and wilting of lower plant leaves.
  2. Browning of leaf margins and tips.
  3. Black brown or rotting roots.
  4. Slow to no growth.
  5. Leaf drop.
  6. Crust of fertilizer on soil surface.
browning of leaf medium

From this article – 6 Signs You Are Overwatering Your Plants we learn the signs for over fertilizing plants are very similar to overwatering plants. However, the signs of over fertilization will occur quickly after your fertilize. You will also recognize over fertilization because you know you were temped to push the limits. Always read and follow the label directions.

Why Do Plants Need Fertilizer

Plants need to be fertilized because most soil does not provide the essential nutrients required for optimum growth. Even if you are lucky enough to start with great garden soil, as your plants grow, they absorb nutrients and leave the soil less fertile.

What Happens To The Plant When You Over Fertilize

When you add too much fertilizer to the soil plants cannot take up water. Plants rely on an osmotic pressure gradient in order to collect water. When the concentration of dissolved solids rises continuously from the soil around the roots to the core of the root, this causes water to flow into the plant. When the pressure around the roots gets too high the flow of water reverses. This is where the term burning your plants comes from. The water is flowing from the leaves out the roots and the leaves burn because they don’t have water to cool them.

Plants adjust to variations in the level of nutrients around their roots but they do best when the level is consistent. This is one of the main benefits of fertigation. Fertigation provides a little bit of fertilizer each time you water so the level around the root stays consistent. This is much better than occasionally shocking your plants with fertilizer. Plants are just like us. We perform better and feel better when we don’t get to full or too hungry. Moderation is the key for our plants and us.

Too much fertilizer can be bad for the environment. If you add too many nutrients excess fertilizers are leached into our ground water, rivers and oceans. This is a concern for people with a few plants because cumulatively in landscapes the amount adds up quickly. Farmers are concerned too because many use large amounts of nitrogen for their crops.

How To Save An Over Fertilized Plant

When you do get carried away with fertilizer or just have a build up of fertilizer in your potted plants there are some steps you can take to save your plants. Leach the fertilizer out of the soil with a long watering taking the fertilizer out of the root zone or out the bottom of the pot. If there is a crust of fertilizer on the surface of the soil remove it carefully. Don’t take more than ¼ of soil with it. Remove the wilted or and burned leaves. Stop fertilizing and rethink the amount you are using. You have a good chance of saving the plant.

You really don’t have to be a chemist to be a good gardener or grower. However, awareness of how fertilizers impact your plants will improve your success rate. If you enjoyed this article please subscribe to the blog or follow me on twitter @H2oTrends


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14 Responses

  1. Richard, thanks for informing me that too much fertilizer would cause my plant’s leaves to burn because they wouldn’t be getting enough water. Moreover, too much fertilizer is also bad for the environment since it would end up in various bodies of water. My husband and I are planning to grow corn in our 20-acre farmland and use subsurface injection fertilizer to help it grow. I’ll take note of what you said so we would not make the mistake of overfertilizing our crops. Thanks a lot!

  2. Great to see that you wrote an article about over fertilizing plants! It is indeed the case that the leaves can burn when you use too much fertilizer, yet many people don’t realize this. At LignoStar we also notice that our customers often forget this.
    Cheers Anne

  3. I want to see how big I can get my tomato plants, not worried about crop yield, just plant size. Growing them in grow bags in organic potting mix. Plant food is Yates Thrive Fish Blood & Bone. Dilution mix is 40 – 80ml to 9 litres of water and application is every one two two weeks. It seems to me that you don’t know how much the plant gets (how long you soak the area, how dry the soil is) or how long the nutrients last in the soil. I had an idea, hey, perhaps I could just feed the plant with a much more diluted plant food continually, instead of hitting it with a belt once a week. But how would I calculate that dilution factor? Would you have any advice???????????????? My theory is this if the plant is to have 1 hit of 80mls/9litres every 10 days then I could just use a continual dilution factor of a tenth so continually water (when needed say every day) using a solution of 8mls per 9 litres of water???? What would your thoughts be on that idea???Thanks, Dave

  4. Thank you for sharing how to effectively fertilize your Plants. I have never seriously started a garden, but I have always wanted one. I work hard in my yard to make it look good.

  5. This was a great help. Now I know how to use fertilizers properly and not overused them on my plants. Informative. Thank you for sharing this.

  6. This was a great help. Now I know how to use fertilizers properly and not overused them on my plants. Thank you for sharing the informative article.

  7. thanks for your article regarding excess fertilising and the after effects of it. How ever the system of reversing the feed obserbed by the plants (intake by the plant) was new to me witch causes root decay and the decay of the plant

  8. It really helped when you talked about fertilizers and why you must be careful with how much you use them! Recently, my sister started filling her apartment with plants, and she’s worried about their growth. I believe my sister could benefit from using fertilizer for her plants, so I’ll be sure to suggest it and share your tips with her! Thanks for the advice on how fertilizers help your plants look healthy!https://greeneralternative.com/our-services/

  9. Does over fertilizing make your tree flowers black? All my leaves and flower fell off. They were all black.

  10. Thanks for pointing out that there are different kinds of releases when it comes to applying yard fertilizers. I’d like to get my yard fertilized soon because I plan to start getting more exotic plants put over there. I’d like to make sure that they could be as healthy as possible.


  11. OMG! Thank you very much for showing us just how important it is to pay close attention to our plant’s soil surface for any accumulation of fertilizer crust which might indicate our excessive use of the substance. I just encountered such a phenomenon while strolling around my aunt’s fruit farm yesterday. Well, maybe it’s time she reconsiders this detail so the plant can grow well as normally as possible again. http://www.bolivarfarmersexchange.com/fertilizer

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