Lawn Overfertilized: Signs & Countermeasures
An over-fertilized lawn has many faces. We explain how to recognize the symptoms of overfeeding and what can be done about it.
Excessive use of mineral lawn fertilizers can damage the lawn [Photo: SingjaiStock / Shutterstock.com]
If you take a very close look at your own or neighboring lawns, you will quickly see that there is a bald spot, discoloration or other flat blemish somewhere in almost every lawn. Sometimes the reason for this is simply that choosing the right lawn seed mixture was unsuccessful. Another reason for such lawn damage can be the excessive use of mineral lawn fertilizers. In this article we explain how you can recognize overfertilization and what you can take preventively or acutely against it. If you are also looking for general information on fertilizing lawns, you will find it in our overview article.
If a purely mineral fertilizer is used for lawn fertilization, over-fertilization can easily occur. Light and heavy over-fertilization can be recognized by different features that we would like to briefly introduce to you. Then we give tips on how to save your damaged lawn.
How do I recognize over-fertilization on the lawn?
Table of Contents
What an overfertilization looks like depends on how dramatic the overfertilization was. In milder cases, nutrient-typical excess symptoms appear on the lawn plants. We have summarized the most important ones here in a table.
| nutrient | Excess syndrome |
|---|---|
| Nitrogen (N) | – Excessive, pudgy growth; brittle, wavy or thickly swollen leaves – susceptibility to frost damage – Dark green color – susceptibility to fungal diseases – death of the root – Causes calcium and magnesium deficiency: stunted growth, death of the leaf tips, reduced root growth, yellowing |
| Phosphate (P) | – No / hardly any symptoms on the plant – “Fixation” in the soil, with very strong over-fertilization also leaching into the groundwater and pollution of natural waters |
| Potassium (K) | – Causes calcium deficiency: stunted growth, death of the leaf tips |
| Magnesium (M) | – Causes calcium deficiency: stunted growth, death of the leaf tips |
Light over-fertilization is not overly dramatic and does not require treatment. However, in the future you should be careful not to distribute too much of the excess nutrient. Or you can rely on a primarily organic lawn fertilizer such as our Plantura organic lawn fertilizer. This makes over-fertilization almost impossible due to the slow conversion of the nutrients.
If the grass is heavily over-fertilized, it first turns yellow, then brown and finally dies flat. The layman may then speak of “burns”, in fact it is the high concentration of fertilizer salts in the soil that causes problems for the roots of the lawn.
How do the burns in the lawn arise?
The “burns” are caused by the so-called exosmosis. In order to better understand this term, one should study the nutrient uptake of plants a little. Plants actively absorb many of the nutrient ions they need into the root hair cells through special channels. This increases the concentration of ions in these cells. Since water always moves from low ion concentrations to higher ion concentrations, the cells filled with nutrient ions attract and absorb water. In this way, the water rebalances the concentrations in the root hair cells and soil. They say: The water follows the “osmotic gradient”. So plants actively create a kind of suction to absorb water.
This effect is reversed in the case of excessive over-fertilization, hence the term “exosmosis”: If there are suddenly a large number of nutrient ions outside the root, the concentration of particles there is higher. The osmotic gradient then runs the other way round and the plant roots cannot absorb so many ions that there is a higher concentration in their roots. As a result, the water migrates out of the plant and it can no longer maintain its vital functions. Incidentally, road salt also causes damage to plants in this way.
Sharply outlined stains are created by applying too much fertilizer salt at certain points [Photo: mykhailo pavlenko / Shutterstock.com]
Tip : Sufficient amounts of spilled gasoline or gasoline mixture, chain adhesive oil from a chainsaw, pesticides or cleaning agents that have accidentally got onto the lawn can also lead to bald spots. For this reason, devices should only be refueled on paved surfaces and cleaning products do not belong in the garden. In our Plantura Shop you will find environmentally friendly alternatives to harmful pesticides.
What can be done about overfertilization on lawns?
It has already happened: when the fertilizer spreader was filled, the sack with the mineral lawn fertilizer tipped over and the contents were spread over half a square meter of lawn. Now you should do it quickly and thoroughly:
- With gloved hands, remove as much manure from the lawn as possible
- Rake as many fertilizer grains as possible out of the sward with a rake
- Water the affected area long and thoroughly – this will dilute the increased concentration of nutrients
If you have applied far too high a concentration of fertilizer to your entire lawn, then only thorough watering will help. Incidentally, this is even a basic rule when fertilizing lawns: It is best to only distribute fertilizer if rain has been announced within the next day. If this is not the case, the fertilizer must be brought into the ground by watering and diluted.
But if the over-fertilization has happened or a dog has peed a hole in the lawn with its urine unnoticed, the only thing that can help is repairing the lawn at this point. The fast-germinating seeds of Lolium perenne and Festuca rubra, as in our Plantura lawn repair, now protect the bald spot from the emergence of unwanted weeds.
It is of course better to make provisions directly, which we would like to recommend to you at this point. Here are some tips to avoid overfertilizing:
- It is best to use organic or mainly organic fertilizers. These are implemented slowly, even if the distribution is too generous, excessive over-fertilization cannot occur.
- Our Plantura organic lawn fertilizers and organic autumn lawn fertilizers protect you from overfertilization.
- Use mineral fertilizers strictly (and if at all) in accordance with the dosage recommendations.
- Always leave fertilizer sacks on paved surfaces and fill buckets or fertilizer spreader there.
- Always check the function and setting of the fertilizer spreader before use.
- Water after fertilizing or fertilize when it rains.
Fertilize lawn properly: tips for correct application
If you use our Plantura organic lawn fertilizer to avoid over-fertilization, proceed as follows:
- Fertilize 2 or 3 times a year
- Mow your lawn quite short
- Spread 40 to 60 g / m² of our Plantura organic lawn fertilizer by hand or use our recommended settings for fertilizer spreaders as a guide.
- If you don't have a scale at hand: A water glass with a volume of 0.2 L corresponds to 130 g of our fertilizer. Accordingly, a filled 1 L bucket contains 650 g of our fertilizer
- Our mainly organic fertilizers do not cause over-fertilization, but irrigation leads to a faster effect of the nutrients.
With mainly organic long-term fertilizers, the risk of over-fertilization is extremely low
Tip: Is your lawn generally yellow and dry in summer? Of course, this does not have to be related to over-fertilization. If your soil is light and sandy and your lawn is in the blazing sun, you can think about creating a special dry lawn. Our certified Plantura dry grass, which is made up of drought-tolerant grasses, is perfect for this. We are also happy to give you tips on how you can use a potassium-accentuated autumn lawn fertilizer such as our Plantura organic autumn lawn fertilizer to minimize not only frost damage, but also damage caused by drought.
How to fertilize your lawn in the right amount and thus avoid over-fertilization, you can find out here in our overview article.
And in another special article we have compiled general information on lawn fertilizers for you.
* in cooperation with Floragard
