The right fertilizer depends on what is growing in your yard. Here is what to use — and when — for every major grass type.
Not all grass is the same, and neither is the fertilizer it needs. Kentucky bluegrass, Bermuda, fescue, Zoysia, St. Augustine, and ryegrass each have different nutrient requirements, growth patterns, and seasonal feeding windows. Using the wrong fertilizer — or applying the right one at the wrong time — can lead to weak roots, excessive thatch, disease, or outright burn.
This guide covers the ideal NPK ratio, annual nitrogen requirement, application schedule, and product recommendations for each of the six most common grass types in the United States. We also include a seasonal fertilizer schedule and an honest comparison of organic versus synthetic options.
Before applying any fertilizer, consider getting a $15-$50 soil test from your local extension office. It tells you exactly what nutrients your soil already has, so you only apply what is actually missing.
3-1-2 ratio (e.g., 24-8-16)
3-4 lbs N per 1,000 sq ft per year
Early spring (April), late spring (May-June), early fall (September), late fall (November)
Apply slow-release nitrogen for steady feeding without surge growth. Fall is the most important application — it fuels root storage and spring green-up. Avoid high-nitrogen feeds in summer when the grass goes semi-dormant in heat. Iron supplements help maintain color during summer without promoting top growth.
Scotts Turf Builder Lawn Food (32-0-4), Milorganite Organic (6-4-0), Jonathan Green Winter Survival (10-0-20)
4-1-2 ratio (e.g., 16-4-8)
4-5 lbs N per 1,000 sq ft per year
Late spring after full green-up (May), every 4-6 weeks through summer (June-August), final feed in early September
Bermuda has the highest nitrogen demand of any common lawn grass. Start fertilizing only after the grass is fully green and actively growing — never on dormant Bermuda. Feed every 4-6 weeks during active growth. Use a fertilizer with iron for deep green color without excessive top growth. Stop feeding 6 weeks before first expected frost.
Simple Lawn Solutions 16-4-8, The Andersons PGF Complete (16-4-8), Super Juice All-in-One (14-2-4)
3-1-2 ratio (e.g., 24-8-16)
2-3 lbs N per 1,000 sq ft per year
Early fall (September), late fall (November), one spring application (April)
Fescue is more drought-tolerant than bluegrass and needs less total nitrogen. Prioritize fall applications — this is when fescue grows most actively and builds root reserves. Avoid heavy summer feeding since fescue goes semi-dormant in temperatures above 85 degrees. A single, moderate spring application is usually sufficient to carry it until fall.
Scotts Turf Builder Thick R Lawn (12-0-8), Pennington UltraGreen Lawn Fertilizer (30-0-4), Espoma Organic Lawn Food (18-0-3)
3-1-2 ratio (e.g., 15-5-10)
2-3 lbs N per 1,000 sq ft per year
Late spring (May), mid-summer (July), early fall (September)
Zoysia is a slow grower and does not need as much nitrogen as Bermuda. Over-fertilizing promotes excessive thatch buildup, which Zoysia is already prone to. Use slow-release formulas and avoid high nitrogen rates. Core aerate annually to manage thatch. Potassium is especially important for Zoysia to improve stress and disease resistance.
Scotts Turf Builder Southern Lawn Food (32-0-10), Pennington Ultragreen Southern (34-0-4), Lesco 15-5-10
3-1-2 ratio (e.g., 15-5-10) with added iron
2-4 lbs N per 1,000 sq ft per year
Late spring (May), mid-summer (July), early fall (September)
St. Augustine responds very well to iron supplements, which deepen color without triggering excessive growth. Avoid phosphorus-heavy fertilizers unless a soil test confirms a deficiency — most established St. Augustine lawns have sufficient phosphorus. Use slow-release nitrogen and tie your feeding schedule to mowing frequency. If you are mowing weekly, the grass is actively growing and can be fed.
Scotts Bonus S Southern Weed & Feed (29-0-10), Ironite Mineral Supplement (1-0-1), Milorganite 6-4-0
3-1-2 ratio (e.g., 24-8-16)
2-4 lbs N per 1,000 sq ft per year
Early fall (September), late fall (November), early spring (March-April), late spring (May)
Ryegrass germinates fast and establishes quickly, making it popular for overseeding warm-season lawns in winter. It responds well to nitrogen but can be over-fertilized easily — watch for excessive clipping growth. In the Pacific Northwest where it grows year-round, feed lightly in spring and more heavily in fall. Avoid summer fertilization in hot climates.
Scotts Turf Builder Lawn Food (32-0-4), GreenView Fairway Formula (22-0-4), Safer Brand Lawn Restore (10-0-6)
Know your lawn size? Calculate exactly how many bags you need →
Apply a balanced fertilizer (like 24-8-16) at half rate to promote early green-up. This is a moderate feeding — the lawn is waking up but not yet in peak growth.
Do not fertilize yet. Warm-season grasses are still dormant or just beginning to break dormancy. Fertilizing now wastes product and feeds weeds instead.
Apply a weed-and-feed product if broadleaf weeds are present, or a straight fertilizer if weeds are not an issue. This is a full-rate application during peak cool-season growth.
First application of the year once the grass is fully green and growing. Use a complete fertilizer at full rate. This kicks off the active growing season.
Reduce or skip fertilization. Cool-season grasses slow down in heat. A light application of iron or a low-nitrogen product can maintain color without stressing the plant.
Peak feeding season. Apply every 4-6 weeks for Bermuda, every 6-8 weeks for Zoysia and St. Augustine. Use slow-release nitrogen to avoid burn in high temperatures.
The most important application of the year. Cool-season grasses enter their peak growth period in fall. Apply a high-quality fertilizer at full rate. This is also the best time to overseed thin areas.
Final feeding before dormancy. Apply a fertilizer with extra potassium (like 15-0-15) to harden the grass for winter. Stop nitrogen applications 6 weeks before first expected frost.
Winterizer application. A high-potassium fertilizer (like 10-0-20) builds root reserves for winter survival and promotes early spring green-up. Apply before the ground freezes.
No fertilizer. Warm-season grasses are entering or already in dormancy. Any nitrogen applied now will feed winter weeds, not your grass.
Synthetic fertilizers are manufactured chemical compounds that deliver precise nutrient ratios. They work fast — you can see results in 3-7 days. They cost less per pound of nitrogen ($0.50-$1.50 per lb of N) and are available in both quick-release and slow-release formulas. The downside: they do nothing for soil biology, can burn if over-applied, and excess nitrogen can leach into groundwater.
Organic fertilizers are derived from natural sources — composted manure, bone meal, blood meal, feather meal, or biosolids (like Milorganite). They release nutrients slowly as soil microbes break down the organic material, typically over 6-10 weeks. They improve soil structure, increase microbial activity, and are nearly impossible to over-apply. The downside: they cost more per pound of nitrogen ($2-$5 per lb of N), have lower nutrient concentrations, and results take 2-4 weeks to become visible.
The hybrid approach. Many experienced lawn care enthusiasts use both. A synthetic slow-release product in early spring provides a strong start. Organic fertilizer through the summer and fall feeds the lawn while building long-term soil health. This combines the precision of synthetic with the soil-building benefits of organic — and it is the approach recommended by most university extension programs.
Pet and child safety. Organic fertilizers are generally safer around pets and children once watered in. Synthetic fertilizers — especially those combined with herbicides or insecticides — may require keeping pets and children off the lawn for 24-48 hours after application. Always read the product label for specific safety instructions.
Enter your address to get your exact grass area — so you buy the right fertilizer in the right quantity for your grass type.
Then use our fertilizer calculator to get exact bag counts. Also see our when to fertilize guide and when to plant grass seed guide.