A Guide to Fertilizing a New Lawn

Seeding a New Lawn

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Growing grass to create a uniform, green expanse of lawn is seldom a simple process. Grass seed and sod both use large amounts of nutrients which means the quality of the soil is a key factor, and even the best soils don't have enough nutrients to support turf grass. This is especially true when starting a new lawn from scratch where one did not exist before. Whether you decide to work with seed or sod, knowing the right kind of fertilizers and when to use them can make a difference.

Why Fertilize?

Turf grasses need high amounts of nutrients, especially nitrogen and phosphorous, to support strong growth. New lawns are often started in soil that has been compacted, damaged and is low on nutrients, and few soils have the high levels of nitrogen needed to grow grass.

If you sow seed or sod in soil lacking primary nutrients, you are likely to end up with a patchy lawn vulnerable to invading weeds and insects. Erosion and runoff can add to your woes. Starting out with the best possible result in a new lawn can mitigate these problems and help your turf stand up to mowing and normal wear and tear. Regardless of where you plan to create a lawn, the right fertilizer applied at the right time is essential for a good growing environment.

A laboratory soil test is well worth the time and any expense when starting a lawn. Since fertilizers are made up of variable amounts of nutrients, knowing what the soil lacks, before you begin, can point you in the right direction for choosing the best product. Depending on which state you live in, you may be required to have one before applying phosphorous, as this has been determined to contribute to algal blooms in local estuaries.


Fertilizers are labeled with an NPK ratio that gives the percentages of nitrogen, phosphorous and potassium that make up the product. Nitrogen is the element that gives grass its dark green color. Phosphorous supports root development. Potassium helps prevent disease and gives some winter protection.

What Is Starter Fertilizer?

Starter fertilizers are usually labeled with the word "starter." Descriptions also might include "turf builder." These products have the higher amounts of nutrients a new lawn requires and may feature a quick release nitrogen to encourage rapid growth.

The formulas are a balanced blend of nitrogen, phosphorous and potassium such as an NPK 10-10-10. A blend slightly higher in either nitrogen or phosphorous such as 20-10-10 or 5-10-5 is also acceptable. If you start with sod, choose a fertilizer with a higher percentage of nutrients, such as a 16-16-16.

What formula to use and how much to apply is determined by the condition of your soil, so having the results of a soil test in hand can remove a lot of guesswork.

How to Use Starter Fertilizer

Choose a granular type starter for a new lawn. Some premixed ready-to-spray products are available and convenient for treating problem spots. They aren't cost effective, though, for covering large expanses.

Starters are applied just prior to or after planting. Both methods are effective and offer advantages so it boils down to a matter of choice for the homeowner.

Adding starter fertilizer to the soil and tilling it in beforehand releases the nutrients, making them immediately accessible to the seed or sod. and can accelerate germination and root growth. This method also avoids the potential for burn on new sod and the delicate roots of sprouting seed.

If you choose to add starter after planting, water substantially. This methods offers the convenience of watering in the fertilizer at the same time you're watering the planting. It saves time by eliminating a few extra steps.


Do not use "weed and feed" type fertilizers with grass seed or sod. These types include herbicides that can prevent germination and slow the growth of a strong root system. Wait at least three to four months until the lawn is well established.

When to Feed a New Lawn

A second application of starter fertilizer is recommended once the seed has germinated or, if you've chosen sod, once the sod has rooted in. You can test by grasping a handful of the sodded grass and giving it a gentle tug. If it remains in place and doesn't pull up this mean roots are establishing. The nutrient needs differ slightly for a newly seeded lawn versus a sodded lawn after the grass is up and growing.

Fertilizing a Newly Seeded Lawn

Depending on your climate and the variety of turf grass you've chosen, the new lawn may be ready for a second feeding anywhere from four to eight weeks after sowing seed. Nitrogen is the element used most, at this point, so choose a fertilizer with a greater amount of "N" for the NPK ratio. An example of a good choice might be 24-25-4.

Fertilizing a Newly Sodded Lawn

A newly sodded lawn can be fed with the same starter fertilizer such as a 16-16-16 applied at planting time. Considerations of grass variety and climate also apply here and help determine the amount of fertilizer needed at this stage of growth.

When to Use Regular Fertilizer

After two applications of starter, provided the lawn has established, you can begin a schedule of feeding your lawn with regular fertilizer according to your climate, and grass and soil type. How often to fertilize depends on how much time and effort you are able to allocate to lawn maintenance. Some recommendations call for feeding three times annually in early spring, mid-summer, and early fall. Others suggest that fertilizing once in early spring or early fall is sufficient to keep your lawn green and healthy


Adding more than recommended amounts of fertilizer won't help and, in fact, can damage grass. Brown or yellowing tips and patchy dead spots are signs you are feeding too much or too often.

Article Sources
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  1. Fertilizer | university of Maryland extension

  2. Fertilizing Lawns. UMN Extension