Grass Seed or Fertilizer: What Do You Put Down First?

Starting a new lawn from seed requires careful preparation to encourage even germination and proper growth. Grass seed needs a starter fertilizer to boost its initial growth. So, what do you put down first, grass seed or fertilizer?

Fertilize an area to be seeded before sowing. This prevents you from disturbing your newly seeded lawn. It also ensures nutrients are readily available to grass seed and seedlings. 

Grass seed or Firstilizer First?

Yes, it’s important to fertilize the soil before planting grass seed to establish even germination and proper growth. Adding nutrients into the soil will ensure newly germinated seedlings have the right nutrients to grow healthy and fast. Here is how to prepare for seeding: 

1. Conduct Soil Test

Before doing anything on the site, conduct a soil test to determine the pH and nutritional condition of the soil. Performing a soil test will tell the exact nutrients that are inadequate and the proportions required. Take a sample of your soil to a nearby university extension or gardening center for testing.

2. Clear and Till the Site

Clear the site to remove small bushes, dead plants, sticks, stones, and other debris. Till the land up to a depth of 6 inches. Break up the large clods of soil and grade the area to ensure it’s sloping away from nearby buildings. Fill any dips with loose garden soil and make the area evenly flat.

3. Amend the Soil

Add organic materials into the soil to improve fertility, drainage, and aeration. Apply at least a 2-inch layer of well-decomposed compost on the surface of the soil and mix it with the soil to about 6 inches. Be sure not to use fresh compost or manure that may introduce weeds and diseases into your garden.

4. Correct the Soil pH

Adjust soil pH as needed by adding lime or sulfur. Most grass varieties thrive and establish well in soil with a pH of 6.0 to 6.8. If the pH is high or low, follow the recommendations provided by the soil test results. If the pH is too high, apply sulfur to bring it down within the recommended range. On the other hand, apply lime if the pH is too low.

5. Fertilize the Area

Apply starter fertilizer before planting the seed. If you conducted a soil test, apply according to the recommendations provided. Select the best fertilizer that suits your soil nutritional needs. 

Generally, you can apply 1 pound of starter fertilizer per 1,000 square feet. Use slow-release fertilizer since it releases nutrients slowly and longer as needed by plants. Choose a fertilizer that doesn’t contain herbicides. It can prevent grass seed from germinating.

6. Rake and Sow Grass Seed

Rake the area to obtain smooth and fine soil particles. Remove sticks, rocks, and other debris that may have remained in the soil. Apply grass seed on the soil surface as recommended on the package. Use an empty roller to gently firm the soil.

Mulch and water

Although not mandatory, it’s recommended that you cover the seeded area with a layer of mulch. You may use straw or any other organic mulch. Apply a thin layer that will help lock in moisture, deter speeding winds and water, and keep away birds and animals that feed on seed. Finally, water your seeded lawn accordingly.

How Long After Fertilizer Can You Put Down Grass Seed?

You can plant grass seed immediately after fertilizing the area. The initial fertilizer will help to feed the grass seed as germination takes place. Since you’re watering regularly to keep the soil moist during the germination period, nutrients may leach out of the soil relatively fast. 

Therefore, you’re required to fertilize your seeded lawn with a second round of starter fertilizer after 4 weeks of seeding. Apply according to the manufacturer’s recommendations provided on the package.

Weed-and-feed products should never be applied immediately before or after seeding. They contain herbicides that kill grass seedlings or prevent germination from taking place. If you applied fertilizer containing herbicides, wait for 8 weeks before planting grass seed. 

Will Fertilizer Kill Grass Seed?

Yes, using regular fertilizer instead of a lawn starter can kill grass seed. Regular fertilizers don’t contain enough phosphorus needed by newly germinated grass. Instead, it will suffocate grass seedlings with excess nitrogen and potassium that are not necessary in the initial growth stage. 

Some regular fertilizers also contain herbicides or pre-emergent ingredients to control crabgrass and other weeds in your lawn. They’re ideal for an established lawn. Such fertilizers can disrupt the seed from germinating when used on a newly seeded lawn. 

Herbicides, or better known as pre-emergent, are made to prevent germinating seed from establishing roots. However, these herbicides cannot distinguish between harmful weeds and the desirable seeded lawn. Although they are aimed at killing broad-leaf weeds, they can injure immature grass seedlings.

Be sure to follow the manufacturer’s instructions when using fertilizers containing herbicides. Generally, you should refrain from applying fertilizers containing herbicides 6 to 10 weeks before or after planting new grass seed.

It’s also important to conduct a soil test before applying fertilizer to determine the type of nutrient needed in your soil. Generally, starter fertilizers should be applied at 0.5 – 1 lb. of nitrogen per 1,000 square feet of lawn. Applying excess nitrogen fertilizer can burn and kill your newly germinated grass seedlings.

What is the Best Fertilizer for Grass Seed

Choosing the right starter fertilizer is key when starting a new lawn. Starter fertilizers are different from other fertilizers that you use on an established lawn. The percentage of phosphorus in an N-P-K starter fertilizer may be higher or the same as the percentage of nitrogen. The percentage of potassium is usually equal to or lower than that of the three primary nutrients. 

Phosphorus is vital for the initial growth of lawn grass. It promotes the healthy development of roots. That’s why the main purpose of a starter fertilizer is to develop a strong and healthy web-like root system.

Starter fertilizer may also contain other micronutrients such as iron, manganese, and sulfur to kick-start a healthy growth of grass seedlings. 

Here are some of the best starter fertilizers in the market, which are best for grass seed. 

1. Scotts Turf Builder Starter Fertilizer

Scotts Turf Builder starter fertilizer contains nitrogen, phosphorus, and potassium (N-P-K) in a ratio of 21-22-4. The ratio of nitrogen and phosphorus is higher thanthat of potassium to give newly germinated grass a healthy, lush green growth and proper development of the root system, respectively. 

Generally, the application rate of Scotts Turf Builder is 4.3 lbs. of starter fertilizer per 1,000 square feet of lawn. However, be sure to read the application recommendations indicated on the package. Both over- and under-fertilizing can be detrimental to your grass seed.  

2. Andersons Starter Fertilizer

The Andersons starter fertilizer contains an N-P-K ratio of 18-24-12. This is a perfect blend of Nitrogen, Phosphorus, and Potassium to give your seeded lawn a healthy start. It is a slow-release fertilizer designed to release nutrients slowly as required by the plants. 

It is the best choice when overseeding an existing lawn. Its slow-release properties ensure both established and newly germinated grass seedlings benefit from the nutrients. If a fast-release fertilizer is used, an established lawn will absorb the nutrients faster than newly germinated grass.

3. Ferti-Lome New Lawn Starter Fertilizer

Ferti-Lome New Lawn starter fertilizer contains an N-P-K ratio of 9-13-7. It also contains other micronutrients such as iron, zinc, manganese, and boron that will give your seeded lawn a quick start. The low levels of nitrogen are best, especially when using this fertilizer to over-seed an existing lawn.

4. Jonathan Green Starter Fertilizer

Jonathan Green Starter fertilizer contains an N-P-K ratio of 12-18-8. It has a high percentage ratio of phosphorus to develop strong roots. Healthy lawn grass requires deep and well-developed roots to obtain water and nutrients from the deeper surface of the soil.

It also contains nitrogen and phosphorus to promote lush green growth after germination, as well as protecting the newly germinated grass from drought and diseases attack respectively. 

5. Yard Mastery Starter Fertilizer

Yard Mastery starter fertilizer contains an even N-P-K ratio of 12-12-12. It is also common to have ratios of 10-10-10 and 19-19-19. However, the balanced ratio of 12-12-12 is the best choice for a seeded lawn since it also contains other micronutrients such as iron, manganese, zinc and Boron. 

Final Thoughts

Always fertilize first before sowing grass seed. It’s also ideal to conduct a soil test so that you are able to select a suitable starter fertilizer. The results will indicate pH and the level of nitrogen, phosphorus, and potassium needed by the soil for healthy growth and establishment of your new lawn grass.