Over Fertilization Of St Augustine Grass

Feeding our lawns with fertilizers really is vital to achieving a Saint Augustine grass lawn which is in its greatest possible health, remains the greenest all year round, and resists weeds, pests and diseases naturally. For most lawn owners, fertilizers are vital to achieve a beautiful Saint Augustine lawn. However there are major concerns with lawn fertilizers, and one of the most important concerns arises from the overuse of these fertilizers by lawn owners who are keen to have the most beautiful lawn in the street. So lets take a look at some of those concerns to understand the equal importance of fertilizing St Augustine grass in correct moderation of use.

Following are the major areas of concern for over-fertilization of Saint Augustine grass.

Excess Thatch and Growth

Saint Augustine grass is well known for that thick layer of thatch that slowly but surely builds higher and higher over the years, this is especially true when Saint Augustine grass is grown in full sun instead of its peak growing environment of partial shade.

Overuse of fertilizers is well known to create faster growth rates in all lawns in both green leaf matter and the thatch layer, and the same is true for Saint Augustine grass too.

This will not only increase the amount of lawn mowing required as we must match the frequency of lawn mowing with the growth rates of the lawn, but we may also expect the lawn to be scalped at the next lawn mowing, which will make the scalped areas brown and ugly and taking weeks to repair, but will also greatly aid in the increase of the excessive Saint Augustine thatch at significantly greater speed.

Environmental Damage From Lawn Fertilizers

Yes it is true that fertilizers do cause environmental damage, and it’s the phosphate in many commonly used fertilizers which cause those ugly algal blooms in some of our waterways. But such things have been proven over and over to be caused primarily by commercial agriculture and from not home fertilizer use.

Also, if lawns are fertilized properly, then the lawn should use every bit of fertilizer applied to it, with next to zero runoff into the environment. It’s the same as a plate of food for a person, if we serve too much, the person gets full and the remainder is thrown away. If we give too much food to the lawn at any one time, it too can only absorb so much fertilizer at any one time until it is unable to take in any more, and the excess is then washed away into the environment.

Overfeeding Makes For A Very Sick Lawn

As we just used the scenario of the Saint Augustine lawn only being able to take in so much of its food source (nutrients from fertilizers) at any one time, before it can take in no more. The reality is the lawn will actually overfeed itself first before it can stop any further uptake of nutrients.

And it’s from this same overfeeding, that the excess nutrients can become toxic within the Saint Augustine grass, and will result in the lawn becoming quite sick. Which is the opposite result of what we were trying to achieve by fertilization of the lawn in the first place.

And in such a weakened state, which may take months for the lawn to recover from depending on the time of the year the lawn damage occurred, the lawn will be in a highly weakened state for a greater period of time, making it far more susceptible to diseases, weeds and pest invasion.

Fertilizer Burning Saint Augustine Lawn

The over application of lawn fertilizer, if done at a time of year when the weather is hot, can also easily result in the St Augustine lawn being badly burnt and severely damaged from a combination of the fertilizer and heat of the day in the blazing sun.

If fertilizer is left on any lawn for too long during a hot day, the lawn will become burnt very quickly, the lawn will turn brown depending on the amount of fertilizer which is left sitting on the lawn and the temperature of the heat of the day.

Over fertilization simply and massively increases the possibility of this severe damage occurring to our lawns during hot weather.


As we can see from the points already covered, over-fertilization of our Saint Augustine lawn can have dramatic damaging impacts on our lovely lawn, not only risking immediate damage from fertilizer burn and scalping from lawn mowing, but also increasing the thatch layer of the Saint Augustine at far greater speed over time. And then, we may possibly also weaken our lawn, making it sick and prone to invasion of lawn weeds, pests and diseases, and finally, we are adding to possible environmental damage where none needs to occur.

And of course the final point comes down to money. Over-fertilization of our St Augustine lawn can be a huge waste of money, not only in buying the excess fertilizer itself, but also from the extra lawn mowing, repair of damaged or diseased lawns, as well as from possible extra costs associated with de-thatching the lawn more often, or even leading to its possible eventual demise years earlier than it should be as the thatch layer finally becomes unmanageable so much sooner than need be.

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