FAQs: Can you apply grass seed and fertilizer together?

Are you also confused how to apply grass seed and fertilizer together, or are you confused as to whether you’re even supposed to use them simultaneously or not? Hop on to my article to know what and how to do it.

Applying grass seed and fertilizer together seems like a good idea, no? An average person would think that simultaneous application of both the products would result in fast and effective growth as both the products work for the plant’s growth and development and its stems. And as the name suggests, fertilizers play an even important role in causing the leaves and stems to be healthy and the roots strong as fertilizers comprise a large amount of phosphorus and nitrogen.

However, applying grass seed and fertilizer at the same time is not at all recommended as it can do more damage than good. That is because, a simultaneous application of both can cause uneven distribution of both the products and can result in burned seedlings, owing to the excessive amount of fertilizer or dry, patchy surfaces. And neither of these is what we desire.

With that being said, let’s deeply study the relationship between grass seed and fertilizer below:

Can I spread grass seed and fertilizer at the same time?

No. You might think you’re saving your time by applying both the materials together, but really, you’re just ruining your resplendent garden. Both the products are to be implemented at separate times. With the fertilizer (if not a starter) and seeds applied simultaneously, the seeds will not develop at all, no matter how much you water it or moisten it or look after it.

Should I fertilize when I plant grass seed?

No, it is not advisable to fertilize soil while planting seeds. That is because it can become a cause for the irregular scattering and irregular growth of plants. It can result in damaging your lawn, leaving dry patches having colors like yellow or brown and making it look scorched.

Also, the thumb rule for fertilization is ‘Less is more‘. Fertilization may nourish your plants and help them grow better; however, adding more fertilizers can burn them out. And resultantly, make your lawn look untidy, cluttered, and mutilated.

How long after putting down grass seed can I fertilize?

You can fertilize the lawn immediately after or before applying the grass seed. This provides the grass with all the nutrients it would require for fast and healthy growth.

Also, when working with grass seeds, remember to plant them when the temperature is between 50ᵒ to 90ᵒ F. In case of the temperature being below 50ᵒ, the seedlings, being planted recently, will be immature and can perish in a frost or extreme cold. And in case of the temperature being above 90ᵒ F, the seeds will not germinate as they enter latency and show little to no growth.

How soon can I fertilize again?

Fertilizing is different for every lawn, but it stands firm in one common aim, i.e., to strengthen the lawn and make it vibrant and healthy. And for that very purpose, you have to visually identify what does and does not suit your lawn and whether it requires additional fertilization or not.

However, for most lawns, you can fertilize them after a good five to seven weeks or till the grass is 1½ to 2 inches tall. This not only constrains the development of weed but promotes deep and healthy, and nourished roots too.

Can I fertilize my lawn every 2 weeks?

No, that’s not the right thing to do. Fertilizing your lawn more often than required can do more harm than good. Application of fertilizer after every two weeks can result in pollution to watercourses, excessive grass germination, or scorched grass.

In general, you should fertilize your lawn four times a year. This, however, is the minimum amount. In the case of a quick-release fertilizer, you might need to deploy it more than only four times per annum.

TIP: How often you need to fertilize your lawn can also be determined by the variation of fertilizer you use and the season currently passing or about to come.

What happens if you over-fertilize lawn?

An over-fertilized lawn is the worst nightmare of a gardener. When you over-fertilize a garden, all the salts present in the fertilizer build up in the soil. This excessive buildup of salt causes the areas where fertilizer has been applied to be dried out or become patchy.

It’s similar to when we consume more salt than required; our tongue feels dry, the heart starts racing, you feel like drinking more and more water, etc.

This dried up part of the lawn often becomes yellow, light brown, or green. And this condition is quite prevalent. This practice refers to fertilizer burn. It’s not always lethal, but it can be hard to tell if your lawn is ever going to recover or not. The remotely yellow color means that the grass is in recoverable stage, but the brown color means you better just say bye to it.

TIP: Recovery of your lawn depends upon the moisture available in the grass, type and amount of fertilizer deployed, and most importantly, the health of your lawn on the whole. Similarly, recovery of your lawn is also dependent upon your intervention and how fast you intercede.

What are signs of over-fertilizing?

Some signs or symptoms that you might notice when your plant is over-fertilized are as below:

  • Fertilizer coating on the top surface
  • Tips of leaves turning brown
  • Lower leaves turning yellow
  • Extremely slow or abandoned germination
  • Defoliation
  • Roots turning black or brown
  • Expiration of seedlings
  • Black colored dots on leaves
  • Leaves drying up

These are some of the most common signs that come into view when the soil is over-fertilized. And in all cases, you should refrain from over-fertilizing your lawn. The less, the better.

Over-fertilization can also be due to the type of fertilizer used. Some fertilizers contain nitrogen, one of the most critical nutrients for the soil’s nourishment, in a vast amount. And with such fertilizers, your lawn requires only a small amount of the product. If applied in excess, it can result in over-fertilization and cause the soil to turn patchy, burned, or, unfortunately, dead.

Is it OK to fertilize lawn in hot weather?

It is not highly recommended to fertilize your lawn in hot weather. Especially if the grass is already dormant, that’s because fertilizing your lawn in hot weather is more harmful than in cold weather. Mow and water your lawn regularly but avoid fertilizing if not utterly necessary.

If you fertilize your lawn in hot weather, the excess of stems, leaves, and growth will outgrow the essence organism causing the root system to be absolutely stressed while the roots put futile efforts into maintaining and nourishing the plant.

In fact, it’s best if you refrain from fertilizing the soil from at least one month prior to summer arriving in your area. This will buy your lawn and the seeds planted in it enough time to adjust and adapt to the new environment.

Also, remember to feed your lawn one last time in spring or before the temperatures increase, i.e., before summers arrive. Apply a slow-release fertilizer so that your lawn is all geared up to begin its new growth when next spring starts.

How long does it take for a lawn fertilizer to work?

The effects of fertilizer on your lawn depend upon the type of fertilizer deployed or applied by you. A fertilizer basically works by supplying nutrients like nitrogen or phosphorus, etc., required for the grass to grow and perform photosynthesis.

However, the effect of the fertilizer varies with different variations. If it is a quick-release fertilizer, then it’s evident that you will witness fast results, but they won’t last long. In contrast, if you use a slow-release fertilizer, it will begin working over quite a long period but, its effects will last for a longer time.

A quick-release fertilizer (also known as soluble fertilizer) begins showing effects in 16 to 24 hours. A slow-release fertilizer (also known as insoluble or controlled released fertilizer) can take up to three to ten weeks. A granular fertilizer might take up to two to six weeks to show results.

However, a combination fertilizer includes both quick and slow-release fertilizers. And it’s time to act may differ from the two products as mentioned earlier.


Grass seeds and fertilizers give the same benefits, resulting in colorful, mature, and healthy fruits and vegetables. However, both perform different work. A seed germinates and develops into a plant carrying fruits, vegetables, or other stuff. Whereas a fertilizer simply plays the role of enhancing and accelerating the process of growth of the plant.

And hence, the idea of applying fertilizer and grass seed just doesn’t go together. You can apply fertilizer soon after or before planting seeds, but both processes cannot simultaneously occur.

Let us know if you enjoyed this article and if it proved to be helpful to you. Also, do share and like the article, and stay tuned for more updates. Happy Gardening!

Nicolas Wayne

Gardening and lawn care enthusiast

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    1. Nicolas Wayne author

      If you treated your lawn with a granular fertilizer, it is unlikely there was a lot of fertilizing going on. As the product acts rapidly with water (and sun exposure), most of the nitrogen and potassium would have been used up intervening periods before you watered your lawn again will slow down any further growth. If this is not the case, then yes – do not bother not applying it for 10 minutes or more after that treatment; nutrients will continue to be actively taken up by plant roots and leaves which means they remain available to lawns for future needs.

      But I recommend fertilizing your lawn only when the soil has stopped receiving water, for optimal absorption of nutrients. We also recommend watering once or twice after fertilizing to help distribute the fertilizer evenly. The spring and fall are ideal times to fertilize your lawn.