UNDER SOD™ – The First Fertilizer Made Specifically for Under Sod
UNDER SOD™ is here.
The first fertilizer engineered specifically to go under new sod — no more guessing, no more math, no more guessing wrong.
Why Homeowners and Landscapers Have Been Confused for Years
Every spring and fall, the same questions come up:
"What do I put under the new sod?"
"Do I really need a starter fertilizer?"
"Which one actually works?"
Landscapers have heard it a thousand times too. The old advice was always "just use a high-phosphorus starter like 12-25-12 or 18-24-12." That's what the big-box stores pushed, what the old agronomy manuals recommended, and what most people still reach for.
But here's what modern soil biology research shows: high phosphorus actually works against you during the most critical 1–2 weeks after sod installation.
When soil phosphorus levels rise above about 10 ppm available P, the grass plant stops signaling for mycorrhizal fungi. It decides the partnership isn't worth the carbon it costs to feed the fungi, so colonization drops or shuts down entirely. The result? Sod that looks green on top but struggles to root deeply, needs more water, fights more stress, and stays dependent on synthetic inputs.
That's why so many new lawns never quite reach their potential — even when the installer "did everything right."
The Missing Piece: A Product Made Just for Under the Sod
We spent years listening to the same frustration from customers and crews across the Northeast. Even when people found a decent biological product, figuring out the right rate for the soil under each pallet was a pain. Too much = waste and possible burn. Too little = no benefit.
So we built UNDER SOD™ to end that confusion once and for all.
One 25-pound bag. One 500 sq ft pallet of sod. Done.
No measuring. No calculators. No "is this enough?" second-guessing.
How to Use UNDER SOD™ (Foolproof by Design)
- Prepare your soil — rake level, remove debris, final grade.
- Spread one full 25 lb bag evenly over the 500 sq ft area.
- Lightly rake it into the top 3–4 inches of the new soil so the granules and live biology sit exactly where the freshly cut sod roots will make contact.
- Lay the sod immediately, roll for good soil-to-sod contact, and water thoroughly (1 inch the first day, then keep consistently moist for the first 2–3 weeks).
That's it. The name says exactly what it does. The bag makes it foolproof.
What's Inside (and Why It Matters)
- 4-2-5 slow-release NPK base — a low-phosphorus, K-forward grade: gentle nitrogen without the high-phosphorus spike that suppresses mycorrhizae, and raised potassium (5%) for drought, cold, and transplant-stress tolerance through the shock window.
- Named endomycorrhizae (*Rhizophagus irregularis*, *Funneliformis mosseae*, *Glomus aggregatum*, *Glomus etunicatum*) — live fungi that extend the root system far beyond the roots themselves and ferry water and phosphorus back once the symbiosis takes hold.
- **A *Bacillus* PGPR consortium** (*B. amyloliquefaciens*, *B. megaterium* for phosphate-solubilizing, *B. subtilis* for root colonization) **plus *Trichoderma*** (*T. harzianum / T. virens*) — beneficial bacteria and fungi that colonize the establishing root zone, supported by a microbial carbon food source that activates the biology.
- 6% leonardite-derived humic acid plus fulvic acid — builds soil chemistry, chelates micronutrients, and creates the environment the biology needs to thrive.
- 2% cold-water seaweed extract (*Ascophyllum nodosum*) — natural cytokinins and auxins that reduce transplant shock, stimulate root initiation, and help the sod stay hydrated during those critical first days.
- Iron-free by design — we root the sod, we don't green the bag. Greening is a cosmetic you can add later; rooting is the irreversible first-30-days decision.
All in an SGN 90 granular that spreads evenly and works immediately where the new roots need it most.
Backed by Real Science (Not Marketing Hype)
The complete guide to mycorrhizal fungi and new sod rooting on ctsod.com lays it all out with the peer-reviewed studies: high-P starters suppress colonization exactly when the symbiosis should be forming. UNDER SOD™ was formulated to avoid that trap entirely while still giving the sod the moderate nutrients it needs to establish fast.
It's the only product on the market built from the ground up for pre-sod application with this exact biological + chemistry synergy.
Ready for Fall 2026 Installs
UNDER SOD™ launches this fall through CT Sod's Northeast network and select regional partners. Bags are sized, tested, and ready to ship when the season kicks off.
If you're a homeowner planning a new lawn or a landscaper who wants to deliver better results with less hassle, this is the product you've been waiting for.
One bag. One pallet. Real rooting.
UNDER SOD™ — because the best lawns start underneath the sod.
