Grodan Rockwool — Commercial Slabs, Blocks & Plugs
Tell us what the room needs — we'll source it
What's below is what we stock on the shelf day to day, not the ceiling of what we can supply. Building out a commercial room, we can source rolling benches, commercial lighting, dehumidification and HVAC, fertigation and irrigation systems, racking, and the environmental controls that run it — the whole build around the substrate, not just the substrate. If it isn't on the site, ask. That's what a call to either store is for.
Twenty-plus years actually cultivating, not just selling
Matt has spent more than twenty years growing — running under-canopy lighting alongside high-intensity LED, and pulling 4+ pounds per 16 square feet in his own rooms. That's the same experience on the other end of the phone when you're matching a block to a slab, not a clerk reading part numbers off a screen.
Grodan slabs — dimensions for matching your bench and tray
Slab choice comes down to length, width, and depth against your bench or gutter, plus how fast you need it to drain. Real dimensions on everything we stock:
| Slab | Dimensions (L × W × H) | Format |
|---|---|---|
| Expert 20/75 | 36" × 8" × 3" | — |
| Expert 15/75 | 36" × 6" × 3" | — |
| Improved Gro-Slab | 36" × 8" × 3" | Bagged |
| Improved Uni-Slab | 9.5" × 8" × 4" | — |
| Pargro Quick Drain | 36" × 6" × 4" | — |
Expert 20/75 and 15/75 are the same 36" length and 3" depth on two different widths — 8" or 6" — so the choice is really about how much slab you want under a given plant spacing. Uni-Slab is the odd size on the list, a short 9.5" block-format slab rather than a full 36" run, useful where a full-length slab doesn't fit the layout. Pargro Quick Drain carries the extra inch of depth, 4" against the Experts' 3", which is where its name comes from.
Grodan blocks — dimensions from clone to finish
Same approach for blocks: real dimensions, so you can match a block to whatever slab or tray it's going into before it ships, not after.
| Block | Dimensions (L × W × H) | Pack format |
|---|---|---|
| Delta 4 (with hole) | 3" × 3" × 2.5" | Wrapped, or Commercial pack |
| Pro Delta 6.5 | 4" × 4" × 2.5" | Pack of 6 |
| Gro-Block GR10 | 4" × 4" × 4" | Each, or wrapped strip of 6 |
| Gro-Block GR7.5 | 4" × 4" × 3.1" | Whole case, or wrapped 6-pack |
| Improved Hugo | 6" × 6" × 5.8" | — |
| GR5.6 | 3" × 3" × 4" | Strip of 8 |
Delta 4 is the commercial workhorse on this list — a pre-holed 3" × 3" × 2.5" block sold wrapped or in a Commercial pack sized for a facility reorder rather than a single tray. GR10 and GR7.5 both run 4" × 4" footprints at slightly different heights, and both come either loose by the each/case or wrapped in a strip of 6, depending on how your crew prefers to handle them at transplant. Hugo is the largest single block we carry at 6" × 6" × 5.8", built for a bigger finishing plant that's outgrown a standard 4-inch cube.
Propagation, loose media, and trays
A-OK plugs and cubes
- A-OK Starter Plugs, 1.5" — a sheet of 98 plugs, also available at case quantity 36/40.
- A-OK, 2" — a shrink-wrapped sheet of 50.
- A-OK 25/40, 1" cubes — an unwrapped sheet of 98.
Mini blocks, Macro Plugs, and the 1020 insert
- Improved Pro Starter Mini Block, 1.5" — 45 per strip, 50 strips per case.
- Mini Blocks, 1.5" — 45-count, plus a 2" version in a strip of 24.
- Macro Plugs — 50-count.
- Pre-Filled 1020 Insert — pre-cut holes, sized to drop straight into a standard 1020 tray.
Loose Gro-Wool and the Gro-Smart Tray
For anything that doesn't call for a slab or a block, we stock loose Gro-Wool in 3.5 cu ft, and the Gro-Smart Tray — a 78-cell tray sized to carry a full propagation run through to transplant.
Dutch engineering, tested at Wageningen University
Grodan rockwool is manufactured in the Netherlands and developed in partnership with Wageningen University, one of the more research-driven pedigrees in growing media rather than a marketing line. That's part of why it's the substrate we reach for when a facility asks what to standardize a new build on.
How ordering, freight, and will-call actually work
All online orders ship from our Webster, Massachusetts warehouse. Pallets and freight are quoted per shipment rather than sold at the standard web rate, because freight class, pallet count, and delivery address all change the number. Call either store or submit the quote form and we'll get you a landed price.
Prefer to skip freight? Both of our Massachusetts locations offer free will-call pickup: Webster (125 East Main St, Unit B, Webster, MA 01570) is open all seven days, and Milford (350 East Main St, Units 4 & 5, Milford, MA 01757) is open Monday through Saturday. We ship nationwide as well, so being outside Massachusetts doesn't take you out of the conversation — it just means freight instead of a pickup window. See the cultivation facility pricing hub for how we handle larger accounts across every brand we carry, not just Grodan.
Shop the full Grodan catalog
Browse everything we stock from the brand in the full Grodan collection, or go straight to facility-volume pricing on media in Bulk Pricing for Facilities — Soil, Coco & Rockwool Media.
Get a quote
Tell us the slab or block, the count, and where it needs to go, and we'll put a real number on it — not a range, an actual quote.
Call or submit the quote form and you'll hear back from a store that has this stuff on the floor right now.
508-461-5850