Whether you’re overseeding an established lawn, starting over after a full lawn renovation, or planting new grass seed on bare soil, choosing the right starter fertilizer is key.
Starter fertilizer differs from other fertilizers mainly due to the higher levels of Phosphorus (P). This number on the bag (the second number, or “P” of N-P-K) is generally the same as the Nitrogen (the first number on the bag, or “N” of N-P-K) or higher. And the rates of Potassium (the third number on the bag label, or “K” of N-P-K) are either the same or the lowest of the three.
Phosphorus promotes root growth which is vital for the early growth of new grass. Establishing strong roots systems and root development is the primary job of starter fertilizers.
Some other nutrients may also be added to starter fertilizers, including iron, sulfur, and manganese. Be sure never to use a fertilizer with crabgrass pre-emergent unless the starter fertilizer explicitly states “for seeding”. The herbicide will be “Mesotrione” (Tenacity) – never prodiamine, dithiopyr, or pendimethalin as these will prevent your grass seeds from germinating.
Below are the best starter fertilizers to use when overseeding this fall or spring.
- 1 1. Ferti-Lome New Lawn Starter Fertilizer (9-13-7)
- 2 2. Yard Mastery Starter Fertilizer (12-12-12)
- 3 3. Andersons Starter Fertilizer (18-24-12)
- 4 4. Scotts Turf Builder Starter Fertilizer (21-22-4)
- 5 5. Jonathan Green Starter Fertilizer (12-18-8)
- 6 Other items to consider when overseeding
- 7 Starter Fertilizers FAQ
- 8 Starter Fertilizers on Amazon
- 9 Nitrogen and Phosphorus (and Potash)
I really like Ferti-Lome because they include a set of micronutrients in all their fertilizers – including this starter fertilizer for new lawns. Adding micros such as manganese, boron, zinc, and iron to new seedlings is always a good thing.
I personally like the lower Nitrogen levels for overseeding existing lawns. Applying less nitrogen to an existing lawn will not promote quick top growth, allowing the new grass to develop before mowing is necessary. Ferti-Lome spread nicely from my Spyker spreader and germination of my TTTF grass seed too about 6 days.
Applying 4 lbs. per 1,000 sq. ft. will deliver 0.52 lbs. of P per 1,000 sq. ft.
This even ratio of Nitrogen, Phosphorus, and Potassium is a very common starter fertilizer. Some other similar fertilizer blends you might see are 10-10-10 and 19-19-19. We like this “Triple 12” starter fertilizer from Sunniland/Yard Mastery because it also contains 3% Iron, Bio-Nite (which is a biosolid, like Milorganite, but from Florida), and other nutrients for the plant including Boron, Manganese, and Zinc.
Apply 4 lbs. per 1,000 sq. ft. to deliver 0.5 lb. of both nitrogen and phosphorus per 1,000 sq. ft.
3. Andersons Starter Fertilizer (18-24-12)
The Andersons starter fertilizer is the perfect fertilizer blend and ratio of Nitrogen, Phosphorus, and Potassium. This popular 3-4-2 starter fertilizer ratio contains polymer-coated,sulfur-coated urea (PCSCU). This coating provides a long and steady release of nitrogen into the soil. This consistent slow-feeding is vital to the seed and plant growth, allowing a longer feeding from a single starter fertilizer application.
Another good reason for this slow, timed-release nitrogen fertilizer is for overseeding existing lawns. If too much fast-release nitrogen fertilizer is applied to a lawn, the existing grass can uptake the fertilizer and nutrients faster than the grass seed – or even newly-germinated grass. This can cause excessive top growth and crowd out the grass seed and new seedlings.
Apply approximately 4 pounds (lbs.) of Andersons starter fertilizer per 1,000 square feet (sq. ft.) to apply 1 lb. of P to the soil, and 3/4 lbs. of N. At this rate, this 50 lbs. bag of starter fertilizer will cover approximately 12,000 sq. ft. of turf.
There have been some recent supply chain issues so these Andersons fertilizer products have been tough to stay in stock – so be sure to grab some now while they last.
4. Scotts Turf Builder Starter Fertilizer (21-22-4)
Scotts Turf Builder starter fertilizer is a 21-22-4 blend that also contains Mesotrione (Tenacity herbicide). This is a perfect all-in-one starter, particularly for those spring seeding and needing to prevent crabgrass. Scotts starter fertilizer with mesotrione in a built-in crabgrass pre-emergent and can help control crabgrass and other grassy weeds for up to 30 days – all while delivering nearly a full pound of both nitrogen and phosphorus when applied at bag rates (17.2-pound bag over 4,000 sq. ft., or 4.3 lbs. of starter fertilizer per 1,000 sq. ft.). Prevent weeds in your new lawn and feed it at the same time.
5. Jonathan Green Starter Fertilizer (12-18-8)
Jonathan Green develops some of the best grass seed around – from sod farmers to DIY homeowners – and their starter fertilizer is top-notch. They used to make an amazing starter fertilizer with Siduron (a seed-safe pre-emergent herbicide, similar to mesotrione) but unfortunately, their manufacturer stopped production. Hopefully, they’ll soon come out with another starter fertilizer with weed prevention.
One of the best things about this 12-18-8 Green-up starter fertilizer is the convenience – it’s readily available almost anywhere: Yard Mastery, Jonathan Green website, Amazon, and even local nurseries and hardware stores.
Other items to consider when overseeding
While starter fertilizers are the most important product for new seed and overseeding success (outside of the actual grass seed), you should also consider some other products for optimal success.
Starter Fertilizers FAQ
What is the difference between starter fertilizer and regular fertilizer?
Generally, the biggest difference between starter fertilizer and regular fertilizer is that starter fertilizer will contain a much higher percentage of Phosphorus (P). Regular fertilizers that you apply throughout the year will either contain much less or no P at all. The plant generally has a much quicker response to starter fertilizer due to the high NPK rates.
What is the NPK of starter fertilizer?
The N-P-K varies from different products and manufacturers. Some have even ratios such as 19-19-19, while others will have a 3:4:2 ratio, or similar (like 18-24-12). But one common element is that they will all contain higher levels of Phosphorus (P) to promote strong roots and root growth.
Do you really need starter fertilizer?
Yes, the main reason is for the Phosphorus. This promotes root development. Growing strong roots is essential for the early growth of new grass.
Can I use starter fertilizer all year?
No, for a couple of reasons.
1. You do not want to fertilize and push growth all year. For example, cool-season grasses will naturally want to slow down in the hotter summer months. Adding fertilizer, particularly starter fertilizer,
2. Some states (such as Massachusetts) are limited to certain products containing Phos. Some areas are at the time of seeding only, or if the plant soils are deficient in P. Contact your local extension office for details including the yield of all fertilizers and nutrients in your specific region.
Starter Fertilizers on Amazon
Nitrogen and Phosphorus (and Potash)
The high percentage and ratios of two macronutrients are what make a starter fertilizer a starter fertilizer, and perfect for seeding. The nitrogen promotes lush top growth while phosphorus is essential to root growth and root development. The ratio of N to P is either even (1:1) or more phosphorus than nitrogen (1:2 or 3:4).
Common starter fertilizer blends are 1:1:1 (e.g. 10-10-10) and 3:4:2 (e.g. 18-24-12). Other non-starter fertilizers contain much lower P (18-3-6) or none at all (e.g. 24-0-6).
The potassium, or potash, is the “all-around” macronutrient. This helps the plant in stressful climates such as excessive heat and drought.