15-20-10 starter fertilizer phosphorus benefits for new grass

Starter fertilizer supports deeper root development

Controlled-release nitrogen in Lawn Synergy 15-20-10 starter fertilizer

Iron and micronutrients for greener newly seeded turf

An informational graphic titled 'HOW TO APPLY' with three green icon panels and text instructions: Prep The Area, Apply Evenly, and Water Thoroughly. A lawn photo appears at the top left, and a strip of green grass is shown along the bottom on a white background.

An informational graphic titled 'WHEN TO APPLY' with a small photo of a person rolling turf at the top left. The graphic lists three application guidelines: Apply At Seeding, With Sod Installation, and New Lawn Growth, with icons and text on a white background.

Coverage guide infographic showing LB bag coverage by square foot: 18 LB Bag covers up to 4,500 sq ft, 25 LB Bag covers up to 6,250 sq ft, and 50 LB Bag covers up to 12,500 sq ft, with text reading 'APPLY 4-5 LBS PER 1,000 SQ FT' and a strip of green grass at the bottom.

Starter Lawn Fertilizer 15-20-10

Give new grass the nutrients it needs to establish quickly and develop strong roots from the start.

Promotes strong, deep root development
Helps new grass establish faster and grow evenly
Ideal for seeding, overseeding, and new sod

Apply at time of seeding or installation of sod.

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Proven ResultsProfessional-grade products

Made in the USAQuality ingredients

Expert SupportReal lawn experts to help

Build Stronger Roots from Day One with 15-20-10 Starter

Strong Root DevelopmentHigh-phosphorus nutrition supports early root growth, helping new seed and sod establish quickly and evenly.

Stronger Root Development

Phosphorus supports early root growth so new grass establishes faster and stronger.

Faster Establishment

Balanced nutrients help new seed, overseeding, and sod get established quickly.

Healthy Early Growth

Nitrogen supports vigorous top growth and richer green color during establishment.

Built for Early Stress

Potassium helps young turf develop strength and better handle heat, drought, and everyday stress.

Give New Grass the Best Start

New grass needs the right nutrition during the critical establishment period. Lawn Synergy 15-20-10 Starter Fertilizer is formulated specifically for new seed, overseeding, and sod to help developing grass establish strong roots and healthy early growth.

The high-phosphorus formula supports root development, while controlled-release nitrogen provides steady feeding as the lawn establishes. Added iron and micronutrients help support healthy color and vigorous growth without relying on a quick burst of nitrogen alone.

Apply at the time of seeding, overseeding, or sod installation and water in after application.

Select Your Grass Type.

20% PHOSPHATE

High-phosphorus nutrition supports early root development and establishment.

15% NITROGEN

Provides steady feeding during the critical establishment period.

CONTROLLED-RELEASE NITROGEN

Provides steady feeding during the critical establishment period.

IRON + MICRONUTRIENTS

Supports greener color and balanced nutrition in developing turf.

Application Rate

4–5 lb per 1,000 sq ft

Equipment

Broadcast Spreader

When to Apply

Seeding or Sod

After Application

Water In

Guaranteed Analysis

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Total Nitrogen (N)15%

3.8% Urea Nitrogen*

11.2% Ammoniacal Nitrogen

Available Phosphate (P₂O₅)20%

Soluble Potash (K₂O)10%

Sulfur (S)4.7%

Iron (Fe)2.38%

Manganese (Mn).18%

Zinc (Zn).17%

Derived From:

Ammonium phosphate, Muriate of potash, Polymer-coated Sulfur-coated urea, Ammonium sulfate, Ferrous sulfate, Ferrous oxide, Ferrous sulfate, Iron oxide, Ulexite, Manganese sulfate, Manganese oxide, Zinc sulfate, Zinc oxide

*3.8% Slowly Available Nitrogen from polymer-coated Sulfur-coated urea.

Spreader Settings

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Find the right starting setting for your spreader.

Spreader Manufacturer Spreader Model

Select your spreader to see the setting.

Use the recommended spreader range as a starting point. Calibrate to your walking speed, pass width, spreader condition, and measured lawn area.

Spreader settings & calibration guide →

Documents & Labels

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Product Label

What is starter fertilizer?

Starter fertilizer is a higher dose of essential nutrients needed when trying to establish new grass seed or when installing sod. It contains Nitrogen, Phosphorus, and Potassium which all three macronutrients are needed for best results.

When to apply starter fertilizer?

Starter Fertilizer should be applied at time of installing new sod or grass seed. As the fertilizer breaks down and begins to work, it is perfect timing for the new grass to begin taking in essential nutrients.

Should I apply starter fertilizer when seeding or wait until it germinates?

We highly recommend applying starter fertilizer at the time of seeding.

Can I use starter fertilizer to aid in correcting phosphorus and potassium deficiencies?

Absolutely. Starter fertilizer contains both a healthy dose of both potassium and phosphorus which will aid in correcting deficiencies.

When to put down starter fertilizer after overseeding?

We recommend applying starter fertilizer at the same time of aeration and overseeing. Core aeration is always best and it will also help move phosphorus down into the soil layer.

Customer Reviews

Overall rating: 4.866667 / 5 from 105 reviews.

AI Generated Review Summary

Lawn Synergy's 15-20-10 Starter Fertilizer helps new lawns establish quickly with strong roots and vibrant color. Customers report fast germination, improved lawn appearance, and satisfaction with the product's results and shipping.

Summary topics

Lawn Establishment (18%): Based on many customers, the lawn product seems to have helped in getting their new lawn off to a good start.
Product Results (10%): Customers raved about the fast delivery and great results they achieved with the starter fertilizer they purchased.
Lawn Appearance (7%): Customers expressed satisfaction with how their lawn looks after using the fertilizers and grass seeds.
Shipping Speed (10%): Customers appreciated the fast and prompt shipping of their orders, which was mentioned multiple times in the reviews.

Review topics: [].

Review highlights

"From the fertilizers to the grass seeds, our lawn looks healthy and wealthy!" — Lynnisha M.
"Fast delivery; great results!" — Joseph
"I am very happy with my purchase my lawn is looking beautiful." — Anonymous

Reviews

Great customer service

"Hi Tony and Pete, I have a 1 year old lawn with new sod. This is my first time using your product and I am very excited on the long journey ahead and the progress of the products that you make for the customers will make a difference. I am an outdoor guy and I love talking care of my own lawn, because know body can do it like you want it done. So that’s why I reach out to your company for help. Your customer service staff is amazing and I personally spoke to Maria she was very helpful and very knowledgeable and professional, that makes a difference over the phone. So as of now I have no photos to share, but I will in the near future. Remember always put your customers first before profit and they will always come back. Thank you, Tim Marshall"

— Timothy M. (5/5)

My seed was spread and

"My seed was spread and fertilized the same day. Germination was so fast and it is a beautiful stand. I love it."

— Lora N. (5/5)

Grass loved it

"I used it with overseeding turned my grass a dark green and filled in the bad spots. Wish I had some before and after shots"

— Jeffrey E. (5/5)

I have been using Lawn

"I have been using Lawn Synergy products for about 2 years. I'm on the subscription plan and it arrives when needed. Neighbors have said how good the lawn looks. It is the darkest green and thickest grass on the block!"

— Richard S. (5/5)

After using your product most

"After using your product most of the summer I have noticed a huge difference in color and thickness. Your advice and product are amazing"

— Scott J. (5/5)

Awesome, new grass seed sprouted

"Awesome, new grass seed sprouted in 7 days and growing every day. Excellent product."

— Louis C. (5/5)

Yes sir working out well

"Yes sir working out well for me thank you !"

— Ben O. (5/5)

Early days. Some grass poking

"Early days. Some grass poking through"

— Norman C. (5/5)

Great results

"I used your product. High in nitrogen. Our grass turned out dark green. Just like I wanted itMy neighbors asked me how do I get my Yard so dark green?"

— Terry (4/5)

"always great product, I love this store."

— Rudy (5/5)

Q&A

When do I reapply? I love the results already. I have St Augustine grass in east Texas: You can reapply in 5-6 weeks. If your area, you can apply emerald 10-0-20 next.
When do I reapply? I love the results already. I have St Augustine grass in east Texas: Suggest applying fertilizer again in 6 weeks.
I have a new sod lawn in North TX. I was going to apply this. Is now a good time? The law is established now and about two months old most areas and over a month old in others. I wanted to fertilize to help it grow its roots.: Yes, this would be a great choice for new sod or new seed.
Hello, As a DYI person, can this be applied to existing lawn ? I have Kentucky Bluegrass,my area is in Illinois . Thanks l: I have Bermuda, but it worked well for me
Can you add this the hole before you put in grass plug? If so, how much?: Yes at 5lbs per 1,000 sqft would be ideal.

Three bags of lawn care products from Lawn Envy, including North Star 20-0-10 fertilizer, displayed on a green grass surface against a dark green background.

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