When and how to fertilize in spring?
Spring fertilization is the most debated topic in lawn care. Fertilizing too early promotes weak top growth at the expense of roots, while waiting too long misses the growth window.
- Apply a balanced starter fertilizer when overseeding4
When seeding bare patches or overseeding in spring, use a starter fertilizer with higher phosphorus (e.g., 10-18-10 or similar) applied at the time of seeding.
📌 commercial2/8/2026, 5:27:35 AM
🛠️ Starter fertilizer, drop or broadcast spreader
- Use a soil test to determine actual nutrient needs first5
Before buying any fertilizer, send a soil sample to your county extension lab. The test costs $15-30 and tells you exactly what your soil needs — and what it already has enough of.
📌 research2/8/2026, 5:27:29 AM
🛠️ Soil sampling kit or garden trowel, plastic bag
- Fertilize warm-season grasses only after full green-up5
Do not fertilize bermuda, zoysia, St. Augustine, or centipede grass until it has fully greened up and is actively growing. This means waiting until 2-3 weeks after the last frost, when nighttime temperatures are consistently above 60-65°F.
📌 best practice2/8/2026, 5:27:23 AM
🛠️ None
- Keep spring nitrogen rates low to prioritize root growth4
Limit spring nitrogen to no more than 0.5 lb of actual nitrogen per 1,000 sq ft. Save the heavier applications (0.75-1 lb N per 1,000 sq ft) for fall, which is the most important fertilization window for cool-season grasses.
📌 best practice2/8/2026, 5:27:17 AM
🛠️ None
- Match fertilizer timing to soil temperature not the calendar5
Use a soil thermometer to guide fertilizer timing rather than calendar dates. For cool-season grasses, wait until soil temperature at 4-inch depth consistently reaches 55°F. For warm-season grasses, wait until soil hits 65-70°F.
📌 best practice2/8/2026, 5:27:12 AM
🛠️ Soil thermometer
- Topdress with compost as a natural slow-release fertilizer4
Spread a quarter-inch layer of screened compost over the lawn, ideally after core aeration. One cubic yard covers approximately 1,000 sq ft at this depth.
📌 diy2/8/2026, 5:27:07 AM
🛠️ Screened compost, wheelbarrow, rake or compost spreader
- Apply corn gluten meal as organic fertilizer and mild pre-emergent3
Spread corn gluten meal (9-0-0) at 20 lbs per 1,000 sq ft in mid-spring. It provides slow-release nitrogen and has a mild pre-emergent effect on crabgrass and other annual weeds.
📌 commercial2/8/2026, 5:27:01 AM
🛠️ Corn gluten meal, broadcast spreader
- Use Milorganite for slow organic nitrogen4
Apply Milorganite (6-4-0) at 16 lbs per 1,000 sq ft in late spring. It releases nitrogen slowly over 8-10 weeks and includes 2.5% iron for natural dark green color without surge growth.
📌 commercial2/8/2026, 5:26:55 AM
🛠️ Milorganite fertilizer, broadcast spreader
- Apply a slow-release synthetic fertilizer in late spring4
Choose a slow-release granular fertilizer (look for "slow-release" or "controlled-release" on the label) and apply at the bag rate in late spring, typically late May for cool-season lawns.
📌 commercial2/8/2026, 5:26:48 AM
🛠️ Slow-release granular fertilizer, broadcast or drop spreader