Potassium Fertilizer and Topdressing for Lawn Care: Sourcing Guide

Homeowner seeking potassium-dominant fertilizer (highest of three N-P-K numbers) and sand/peat/soil topdressing mix. Local store (OSH) unfamiliar with request. Needs product identification and sourcing.

Understanding Fertilizer Labels

N-P-K = Nitrogen-Phosphorus-Potassium (always in this order). "Potassium-based" means K is the highest number, e.g., 3-3-12, 0-0-22, 5-5-20.

Potassium Fertilizer Types

Where to Buy

• Golf course supply companies – Carry professional grades (e.g., Harrell's, LebanonTurf)
• Landscape/irrigation distributors – Ewing, SiteOne, Horizon
• Co-op / farm supply – Bulk bags, agricultural grades
• Online: Amazon, DoMyOwn, Solutions Pest & Lawn
• Specialty garden centers – Not big-box stores

Topdressing Mix (Sand/Peat/Soil)

Classic ratio: 1:1:1 by volume

• Sand: Medium-coarse, washed (not play sand, not masonry sand)
• Peat: Sphagnum peat moss (or coconut coir for sustainability)
• Soil: Screened topsoil or compost (compost preferred)

Application Timing

• Cool-season grasses: Early fall (Sept-Oct) – best root growth
• Warm-season grasses: Late spring (May-June) – active growth
• Topdressing: After aeration, during active growth
• Potassium: Fall application critical for winter hardiness

DIY Sourcing Strategy

1. Call local golf course superintendent – ask where they buy
2. Search "turf supply + [your city]"
3. Order 50-lb bags – cheaper, stores well dry
4. For topdressing: bulk delivery from landscape yard (1-2 cubic yards)

Don't let retail ignorance stop you. Professional turf products exist—you just need the right supplier channel.