Should you seed or fertilize first in spring? Expert advice to help you decide the order best for you

Q:  Spring is on the horizon and I want to prepare my lawn for the warmer months ahead. I plan to over-seed the bare patches with cool-season grass. I also want to apply fertilizer to give it a boost and get it to look green and lush. However, I'm not sure whether to sow seed or fertilize first. Does it matter, and if so, which order is best?

A: Both of these lawn care tasks are great for getting a lawn back into shape after inclement winter weather. There are two choices at your disposal, depending on the type of feed you use, and both can give you the lawn you aspire for. 

The first option is to plant the grass seed, then apply a regular lawn fertilizer a few weeks afterwards. An alternative is to fertilize with a starter feed before seeding in spring.

To seed or fertilize first?

Whether you seed before feeding or after, the choice may come down to when you are planting seed and the type of grass you are growing. See some expert tips to help you discover the best route and the types of feeds to use.

Seed before fertilizing

Lawn expert Gene Cabellero of GreenPal hails the benefits of feeding the weeks after planting grass seed when you are sowing in early spring. He says: 'The reason is that the new grass seeds are very delicate and could be damaged by the ingredients in the fertilizer.

'By seeding first, the grass seeds can become established and develop a strong root system as a foundation. Once the seeds are showing good, strong growth, you can then add fertilizers for your particular grass and soil type.'

After the lawn has germinated, around 4-6 weeks after planting the grass seed, you can then apply a round of nutrient-rich lawn fertilizer.

To get rid of lawn weeds, you may also wish to apply a herbicide when you fertilize the grass. But, to avoid damaging your new seedlings, be sure to check the label first. It should tell you how long you need to wait to apply it after sowing fresh seed.

Gene Caballero

Gene Caballero is the co-founder of GreenPal which has been described as Uber for lawn care. He has been in the landscaping business for over 25 years.

Fertilize before seeding

If you use a dedicated starter fertilizer, you can apply feed before sowing the seeds. Applying when you plant your grass seed (either just before or just after) will help speed up the germination process. This is due to the makeup of nutrients in such products.

‘Starter fertilizers usually pack more phosphorous and less potassium than regular fertilizers because they are tailored to the needs of new grass,’ says Jeremy Yamaguchi, the CEO of Lawn Love. 

‘When any plant is first growing, it takes time for its root system to spread and absorb nutrients - which is the case for grass seed. So, this is why starter fertilizer is so helpful. It supplies grass seed roots with the nutrients they need but can’t yet collect from the soil.’

Make sure to only use starter fertilizers in this case, as they are designed for use when sowing seed. A well-rated example is Scotts Turf Builder Starter Food, available from Amazon, which can be applied immediately before or after sowing grass seed. Pennington UltraGreen Starter Lawn Fertilizer, also from Amazon, is another option and includes 5% iron to encourage a deep green lawn. Other types of products, such as weed and feed, may contain chemicals that will inhibit the germination of grass seed. 

Anton Schwarz, the CEO of Lawn Liberty, recommends that you feed before seeding if you are sowing warm-season grasses to repair patches in your lawn, like Bermuda grass and Zoysia grass. These are the grasses better suited to hotter climates in southern states. 

Cool-season grasses (such as Kentucky bluegrass and fescue – better suited to northern states) tend to do best when seeded in the fall or early spring, while warm-season varieties are best sown later, in late spring or early summer.

'Fertilizing should come first in this case,' says Anton. 'Applying a slow-release fertilizer in the early spring, when the soil has warmed up, can help get your lawn off to a good start. It's best to wait a few weeks after fertilizing before seeding, to allow the fertilizer to fully penetrate the soil and avoid the risk of burning the new grass.'

Jeremy Yamaguchi

As the CEO of Lawn Love, Jeremy Yamaguchi helps homeowners find quality, reliable lawn care. Specializing in technology and using industry experience, he intends to revolutionize the lawn care industry.

Anton Schwarz

Anton Schwarz is a seasoned lawn care professional who started his own business to meet the need for high-quality lawn care services around Madison County, AL. He provides a range of services and uses eco-friendly products whenever possible. Anton also runs LawnLiberty.com, an info blog that covers a wide range of topics related to lawn care. 

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FAQs

Can you put lawn feed on new grass seed?

After sowing grass seed, it is best to wait at least another 4-6 weeks before fertilizing the lawn again. The exact time will depend on the type of grass seed, watering, sunlight, and the soil temperatures. New grass wants a lot of nitrogen and phosphorus at this stage of its lifespan, to help put down both strong shoots and roots.  

Overseeding is a great job to put on a spring lawn care to-do list. The soil is warm and moist in spring and sowing fast-growing grass seeds can help repair any patches quickly and effectively.