Best Slow Release Nitrogen Fertilizer for Lawns and Gardens

#1 · Best Overall

1. GreenView Fairway Formula Lawn Fertilizer

• Weight: 33 lb
• Form: Granules

Best for: Medium-to-large lawn coverage.

Why it ranks #1: Its 33-pound bag covers 10,000 square feet, with 63% slow-release nitrogen feeding grass for up to 12 weeks.

Coverage of up to 10,000 square feet from a 33-pound bag makes GreenView Fairway Formula a practical scale choice for medium-to-large lawns. Its 63% slow-release nitrogen feeds grass for up to 12 weeks, aiming for thick growth without surge patterns.

The formula combines immediate-release and controlled-release nutrition, so it provides ongoing feeding while supporting consistent growth rather than surge patterns. Its 63% slow-release nitrogen is stated to feed for up to 12 weeks, helping structure a lawn-care schedule around an extended feeding window. The listed 10,000-square-foot coverage gives buyers a defined area for planning an application. It is intended for actively growing turf and is not a weed or crabgrass-control product.

Skip it if you need weed or crabgrass control in the same application; this formula is intended to feed grass, not control those plants.

A match for owners of medium-to-large lawns seeking extended nitrogen feeding and a stated coverage area. Choose it for lawn nutrition, not weed or crabgrass management, and apply when turf is actively growing.

Listed on Amazon as: GreenView Fairway Formula Lawn Fertilizer 33 lb. Bag, Covers 10,000 sq. ft.

#2 · Longest Feeding

2. Pennington Full Season Lawn Fertilizer

• Weight: 11.2 lb
• Form: Granules

Best for: Season-long lawn application.

Why it ranks #2: Polymer-coated urea releases nitrogen for up to four months, and the 32-0-5 formula includes 5% iron for greening.

One application intended to feed for a season is the central appeal of Pennington Full Season Lawn Fertilizer. Polymer-coated urea releases nitrogen for up to four months, while five percent iron supports deep greening and beneficial microorganisms are included for soil care.

The 32-0-5 formula pairs controlled-release nitrogen with soluble potash, sulfur, and iron, targeting lawn growth and color through a single seasonal application. Polymer-coated urea releases nitrogen for up to four months, which can reduce repeat feeding during that period. The product is applied with a spreader according to package directions and is listed for grasses including Kentucky bluegrass, tall fescue, Bermudagrass, and Zoysiagrass. It is not available in Hawaii or South Dakota.

Skip it if you live in Hawaii or South Dakota; Pennington lists this fertilizer as unavailable in both states.

A strong fit for lawn owners who want one spreader application and up to four months of controlled-release nitrogen with iron for color. It is not an option for residents of Hawaii or South Dakota.

Listed on Amazon as: Pennington Full Season Lawn Fertilizer 4M 32-0-5 RF 3/11.2Lb

#3 · Highest Nitrogen

3. Greenway Biotech Nitroform

• Weight: 16 oz
• Form: Granules

Best for: Long-feed nitrogen concentrate.

Why it ranks #3: The 39-0-0 granular formula contains 28.5% water-insoluble nitrogen and provides a steady supply for three to four months.

The 39-0-0 analysis includes 28.5% water-insoluble nitrogen, giving Greenway Biotech Nitroform a specifically slow-release nitrogen profile. It is stated to feed plants for three to four months, with reduced thatch development in turf applications and less risk of leaching.

Nitroform’s nitrogen is divided among 3% urea nitrogen, 7.5% water-soluble nitrogen, and 28.5% water-insoluble nitrogen, so buyers can see how the 39-0-0 total is composed. The product is described as supplying nitrogen steadily for three to four months, which can space out feeding. Its directions call for applying around plants and watering to activate the material. The one-pound quantity suits targeted applications rather than broad coverage.

Skip it if you need a larger lawn quantity and a defined coverage area; GreenView Fairway Formula covers up to 10,000 square feet.

Consider Nitroform for targeted plant or turf feeding when a high-nitrogen, three-to-four-month release profile suits the plan. Its one-pound quantity is a practical boundary for buyers treating a broad lawn area.

Listed on Amazon as: Greenway Biotech Nitroform 39-0-0 Slow Release Nitrogen Fertilizer- Contains 3% Urea N, 7.5% Water Soluble N, & 28.5% Insoluble N for Healthy Plants & Lawn Growth (1 Pound)

#4 · Long-Feed Lawn Formula

4. Eco Solutions Slow Release Lawn Fertilizer

• Weight: 22 lb
• Form: Granules

Best for: Long-interval lawn feeding.

Why it ranks #4: Its 25-5-10 lawn formula has 65% granular nitrogen and is listed as feeding for up to 110 days.

A 65% granular nitrogen formula that feeds for up to 110 days sets this 25-5-10 lawn fertilizer apart. The blend combines high nitrogen with phosphorus and potassium for lawn growth, making it a long-interval option for buyers seeking steady feeding without frequent applications.

The 25-5-10 NPK blend gives this product a high-nitrogen lawn focus, while its stated feeding period of up to 110 days can simplify seasonal lawn-care scheduling. Granules suit spreading across turf, and the 22-pound quantity offers more material than small garden-oriented formulas. The product is described as safe for kids and pets, but its safety information still directs users to wear gloves and eye protection and keep it out of reach during handling.

Skip it if you need feeding for a shorter interval; GreenView Fairway Formula Lawn Fertilizer feeds for up to 12 weeks.

A fit for lawn owners prioritizing a high-nitrogen formula and a stated feeding period of up to 110 days. Follow the listed protective-equipment directions, and keep the product away from children and pets during storage and use.

Listed on Amazon as: Slow Release Lawn Fertilizer 25-5-10 NPK – 65% Granular Nitrogen Formula for Deep Feeding up to 110 Days – 10kg (22lbs) Bag – Kid & Pet Safe Lawn Care for Lush Green Grass

#5 · Micronutrient Blend

5. Lawn Synergy Almighty

• Weight: 18 lb
• Form: Granules

Best for: Micronutrient-supported lawn feeding.

Why it ranks #5: This 20-0-10 lawn fertilizer uses XCU slow-release nitrogen for up to 10 weeks of plant response and includes iron and other micronutrients.

Lawn Synergy’s 20-0-10 formula pairs slow-release nitrogen with NuTrace micronutrients for sustained green color and root support. XCU slow-release nitrogen is stated to provide gradual nutritional uptake for up to 10 weeks, while potassium and micronutrients address summer stress and lawn vigor.

The 20-0-10 profile combines nitrogen with potassium, and the product description links potassium and micronutrients to stronger roots and improved heat and drought tolerance. XCU slow-release nitrogen provides gradual uptake for up to 10 weeks of plant response, supporting a measured feeding interval. The listed micronutrient blend includes iron, zinc, manganese, magnesium, copper, boron, and amino acids, with iron and other micronutrients tied to color and lawn vigor. Granular form suits lawn application.

Skip it if you want a longer stated feeding interval; Pennington Full Season releases nitrogen for up to four months.

Choose this for lawn feeding that combines slow-release nitrogen, potassium, and a broad micronutrient blend, especially when heat and drought tolerance matter. Its stated XCU response of up to 10 weeks sets the feeding interval.

Listed on Amazon as: Almighty 20-0-10 Lawn Fertilizer (18 lbs.) – Professional Slow-Release Nitrogen Formula with NuTrace Micronutrients – Deep Green Lawn Color, Strong Roots & Drought Stress Recovery

#6

6. GreenView Fairway Formula Fall Fertilizer

• Form: Granules

Best for: Fall lawn preparation.

Why it ranks #6: Made for fall lawn care, it promotes deep roots and steady greening; its listed formula combines immediate- and slow-release nitrogen.

Fall-specific lawn care is the focus of GreenView Fairway Formula Fall Fertilizer, which is described as repairing summer damage and preparing turf for winter. Its granular formula promotes deep roots, thick growth, and steady greening without surge growth across grass types.

This seasonal formula is intended for fall lawn preparation, linking summer-damage repair with winter readiness and a better spring lawn. Its stated benefits include deep root growth, thickening, and steady, even greening without surge growth, useful for buyers looking for gradual color and turf development. It can be used on any grass type. Directions identify a one-time use when seeding a new lawn area, and the safety information says not to hand spread.

Skip it if you want a spring-focused lawn fertilizer; GreenView Fairway Formula Lawn Fertilizer is presented for spring application and active turf growth.

Choose this for fall lawn preparation when root growth, summer-damage repair, and winter readiness are priorities. Its seasonal emphasis and instruction not to hand spread make it a less natural fit for other application routines.

Listed on Amazon as: GreenView Fairway Formula Fall Lawn Fertilizer, 22.5 lb. Bag

#7

7. GroMaster 10-10-10 Plant Food

• Weight: 5 lb
• Form: Granules

Best for: Mixed garden plantings.

Why it ranks #7: The balanced 10-10-10 granular formula specifies 50% slow-release nitrogen, feeding plants steadily for up to three months.

Fifty percent slow-release nitrogen is the key differentiator in GroMaster’s balanced 10-10-10 plant food, feeding plants steadily for up to three months. The granules also include micronutrients, making this five-pound formula a candidate for vegetable gardens and mixed plantings needing broad nutrient support.

Equal parts nitrogen, phosphorus, and potassium give this formula a balanced nutrient profile for varied garden crops, while the listed trace elements support plant development across a wide range of plantings. With 50% slow-release nitrogen feeding for up to three months, the product can reduce the need for frequent feeding and lower fertilizer-burn risk. Granular form suits soil application in mixed gardens; the five-pound quantity is a consideration for larger areas.

Skip it if you need extended lawn coverage; Pennington Full Season feeds lawns with controlled-release nitrogen for up to four months.

A fit for gardeners feeding vegetables and mixed plantings with one balanced granular formula, especially when up to three months of slow-release nitrogen suits the schedule. The five-pound quantity is less suited to covering extensive planting areas.

Listed on Amazon as: 10-10-10 All Purpose Plant Food, 5 lb, with Slow-Release Nitrogen, for Vegetable Gardens and Mixed Plantings

#8

8. Milorganite 6-4-0 Fertilizer

• Weight: 5 lb
• Form: Granules

Best for: Small-scale lawn and garden.

Why it ranks #8: This five-pound, low-salt 6-4-0 granular fertilizer suits lawns, flowers, and gardens; its directions suggest applications every eight to ten weeks.

A five-pound size makes Milorganite’s 6-4-0 slow-release fertilizer a manageable option for smaller lawns, flower beds, and gardens. Its virtually salt-free formula is presented as helping prevent burn in hot or dry conditions, while organically complex iron supports deep green color without concrete staining.

This granular fertilizer combines slow-release nitrogen with a 6-4-0 analysis, making it a lawn-and-garden option rather than a balanced three-nutrient feed. Milorganite’s virtually salt-free formula is described as helping avoid burn across lawns, trees, shrubs, and plants, including in hot or dry conditions. Organically complex iron delivers green color through the feeding period without staining concrete like iron salts. The stated schedule is every eight to ten weeks during grass-growing season.

Skip it if you want equal nitrogen, phosphorus, and potassium for varied crops; GroMaster 10-10-10 offers a balanced formula.

Consider it for smaller lawns or garden areas where low-salt feeding and iron-supported color matter. Its five-pound quantity and 6-4-0 analysis may not suit extensive coverage or buyers seeking balanced NPK nutrition.

Listed on Amazon as: Milorganite All-Purpose Eco-Friendly Slow-Release Nitrogen 6-4-0 Fertilizer, 5 Pound Bag – for Lawns, Flowers and Gardens

#9

9. Milorganite Fertilizer Bundle

• Weight: 32 lb
• Form: Pelletized

Best for: Low-salt lawn feeding.

Why it ranks #9: The 32-pound 6-4-0 pelletized fertilizer includes a printed feeding and spreader tips brochure, but no specific release duration is listed.

The low-salt 6-4-0 formula is the defining feature of this Milorganite bundle, helping reduce streaks, stripes, and fertilizer burn even in hot or dry conditions. Its 32-pound quantity is paired with a printed brochure offering seasonal application and spreader guidance for lawn-care planning.

Pelletized fertilizer makes up the main component, while the included brochure adds practical seasonal application and spreader tips, giving buyers guidance alongside the product. The formula contains organically complex iron, which supports deep green lawn color without the concrete staining associated with iron salts in some synthetic fertilizers. Its slow-release feeding and virtually salt-free composition suit users seeking steady lawn nutrition with less concern about burn in hot or dry conditions.

Skip it if you need a balanced nitrogen-phosphorus-potassium formula; GroMaster 10-10-10 includes all three nutrients in equal parts.

Choose this bundle if you want slow-release lawn feeding, iron for green color, and printed spreading guidance. Its 6-4-0 analysis is lawn-oriented rather than a balanced three-nutrient formula.

Listed on Amazon as: Milorganite 6-4-0 Fertilizer and Feeding Tips Brochure Bundle, 32lb

#10

10. GARDENWISE 10-10-10 Fertilizer

• Weight: 2 lb
• Form: Granules

Best for: Indoor and outdoor plant mix.

Why it ranks #10: This two-pound all-purpose granule feeds for up to eight weeks and suits varied plants, but the listing gives no slow-release nitrogen percentage.

Use across indoor and outdoor plants is the defining feature of GARDENWISE 10-10-10 slow-release fertilizer. Its balanced granular formula is listed for vegetables, fruit trees, shrubs, flowers, lawns, and potted plants, with sustained nutrition for up to eight weeks between applications.

Equal 10% nitrogen, phosphorus, and potassium gives a range of plant types the same balanced nutrient profile, while the granular form suits both garden soil and potted-plant use. The stated feeding period of up to eight weeks can help reduce application frequency for indoor and outdoor routines. At two pounds, it is a compact quantity for targeted plantings or container care; users with larger gardens should account for the amount needed across their planting area.

Skip it if you need a larger lawn application with longer feeding; Pennington Full Season feeds lawns for up to four months.

Choose it for a varied collection of indoor and outdoor plants when one balanced granular formula and up to eight weeks of feeding fit your routine. Its two-pound quantity is better suited to targeted use than extensive coverage.

Listed on Amazon as: 10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables, Tomato, Arborvitae, Shrubs, Rose, Flowers, Fruit, Fig Trees (2 lbs~ 1 qt.)