Quick answer
Put your starter fertilizer down before you lay the sod, not after. Spread it on the prepared, graded soil, rake it lightly into the top inch, then lay the sod on top so the freshly cut roots meet the nutrients immediately — a separate maintenance feeding comes later, about 30 days after installation once the sod has started to root.
Before: the starter goes in the soil
The reason is contact. Sod roots are cut at harvest, and they establish fastest when nutrients and soil biology are already in the zone they're growing into. Applying the starter to the prepared soil, then raking it into the top inch, puts everything in direct contact with the cut roots the moment the sod is laid. A biological starter especially belongs here — the mycorrhizae and beneficial bacteria need to be in the root zone, not sitting on top of finished turf.
Where Under Sod™ fits
Under Sod™ is designed for exactly this step: a 4-2-5 iron-free biological starter applied to the prepared soil before the sod goes down — with named endomycorrhizae, a *Bacillus* and *Trichoderma* biology package, seaweed, and humic acid (plus fulvic acid) — at one 25 lb bag per 500 sq ft pallet, watered in after installation. See the full product specs.
After: only water, then a maintenance feeding at ~30 days
Right after laying sod, the job is water — deep and frequent enough to keep the sod and the soil beneath it consistently moist while the roots knit in. You don't fertilize on top of brand-new sod. Dry fertilizer sitting on the blades can burn the tissue, and the roots aren't developed enough yet to use a surface feeding well. The first maintenance fertilizer comes about 30 days after installation, applied at the labeled rate (not heavier) and watered in thoroughly.
Timing follows standard university turf-extension guidance for cool-season establishment; adjust for your grass type and season.
The full sequence
- Test soil, then grade and prepare.
- Before laying: apply a low-phosphorus biological starter to the soil and rake into the top inch.
- Lay sod, then water in thoroughly.
- Keep watering through establishment (first 2–6 weeks).
- About 30 days after: first maintenance feeding at the labeled rate, watered in.
Frequently Asked Questions
Do you put fertilizer down before or after laying sod?+
Before. Spread starter fertilizer on the prepared soil and rake it into the top inch so the cut roots meet it on contact. A separate maintenance feeding comes about 30 days after installation.
Can you fertilize on top of new sod right after laying it?+
No. Dry fertilizer on the blades can burn the tissue, and the roots aren't developed enough to use a surface feeding well. Right after laying, the job is water — the first maintenance feeding waits about 30 days.
When is the first feeding after installation?+
About 30 days after the sod is laid, once it has begun to root, applied at the labeled rate (not heavier) and watered in thoroughly.
Keep reading
Homeowners and installers are already asking what goes under new sod. UNDER SOD™ is the trademarked brand built specifically for that job.
Built for beneath the sod.
A 4-2-5, iron-free biological starter — named mycorrhizae, beneficial bacteria, Trichoderma, seaweed, and humic acid — at one bag per pallet. Launching Fall 2026 across the Northeast.