Greenhouse Ground Cover: Specs That Last
A weed mat in a greenhouse does four jobs at once: it suppresses weeds, carries foot and trolley traffic, survives wash-down with detergent and disinfectant, and keeps the floor from becoming a reservoir for algae and splash. Most floor failures come from specifying for the first job and discovering the other three later. The specification that holds up is weight, weave and UV package, chosen for the traffic and cleaning regime rather than for the price per roll.
Two product families cover most sites: woven polypropylene ground cover fabric, which breathes and drains, and smooth or embossed film, which cleans and seals but holds water on the surface. The choice is a drainage decision before it is a cost decision.
Why the Floor Matters on a Hydroponic Site
A hydroponic house has no soil buffer and a lot of water on the floor. Whatever covers that floor decides whether the water leaves, where it goes, and what grows in it.
- Splash control. Bare soil or gravel throws water and spores onto lower leaves whenever a trolley passes.
- Traffic. Harvest crews and trolleys run the same routes daily, and the floor has to take that load without rutting.
- Hygiene zoning. A clean floor makes the dirty-to-clean boundary visible, which is what an auditor looks for first.
- Light. A light-coloured cover lifts reflected light into the lower canopy, which matters in winter.
- Cleaning access. If the cover cannot be pressure-washed, the hygiene program has to be written around it.
The floor drainage and hygiene zoning guide covers how the fall, the drains and the zone boundaries should be laid out before any cover is ordered.
Weed Mat Weight and Weave: What Survives Traffic
Specify by weight in grams per square metre first. Standard greenhouse weed mat runs from about 90 to 130 g/m², which suits pedestrian paths and light trolley work. Routes carrying loaded trolleys, forklifts or pallet trucks need a heavier product, and paths that only ever see foot traffic can run lighter.
| Weight | Traffic it handles | Typical position | Expected service life |
|---|---|---|---|
| 80 to 100 g/m² | Foot traffic only, occasional trolley | Under benches, side aisles behind beds | 2 to 4 seasons |
| 100 to 130 g/m² | Daily foot traffic, light trolleys | Main walking aisles, propagation houses | 4 to 6 seasons |
| 150 to 200 g/m² | Loaded trolleys, pallet trucks, forklifts | Central spine, packhouse link, loading bay | 6 seasons or more |
| Heavy-duty coated | Forklift and repeated wash-down | Routes shared with external traffic | Longest, highest cost per square metre |
Weave matters as much as weight. Woven tape fabric holds its shape and drains; non-woven needle-punched felt is softer and quieter, but holds water and dries slowly. Under a bench, felt is comfortable. In an aisle hosed twice a week, it stays wet and grows algae.
UV stabiliser is compounded into the tape, and the same rule applies as with vent netting: ask for the package and the warrantied exposure life, not a generic claim. Under cover the UV dose is lower than outdoors, but disinfectant, traffic and constant damp are what actually end service life. The insect netting specification guide uses the same UV-package logic.
Overlap, Seaming and Fixing
Seams and edges are where a floor fails. The middle of a roll almost never does.
- Overlap 150 to 300 mm on woven mat, more on slope, and lay the uphill sheet over the downhill sheet so water runs over the joint rather than under it.
- Pin or peg at 300 to 500 mm along every seam and at 500 to 800 mm across the field, closer on corners.
- Staple rather than spike where the base is compacted gravel; U-pins pull out, and a lifted seam becomes a trip edge and then a tear.
- Seam parallel to the traffic direction where possible, so wheels cross the joint rather than running along it.
- Do not tape a seam that will be pressure-washed. Tape lifts; sew or heat-weld instead, or accept the overlap.
Drainage and Wash-Down
Decide first whether water should pass through the floor or run across it. That single choice picks the product family.
| Cover type | Water behaviour | Cleaning | Where it belongs |
|---|---|---|---|
| Woven ground cover fabric | Passes through to the base | Washes through; dries quickly | Growing aisles, under benches, weedy perimeter |
| Non-woven felt | Absorbs and holds | Slow to dry; algae risk | Dry zones, propagation, low-traffic areas |
| Smooth PE film | Runs across the surface | Fastest to sanitise; slippery | Packhouse, hygiene-critical zones, runoff collection |
| Embossed anti-slip film | Runs across, better grip | Good; embossing holds dirt | Wash-down areas with foot traffic |
| Gravel over woven mat | Drains freely | Hard to disinfect | Perimeter, external paths, drainage strips |
Fall of roughly 0.5 to 1.5 percent toward the drains keeps water moving without feeling underfoot. Standing water on any cover grows algae within days, and algae on film is a slip hazard as much as a hygiene one. Where drain water is collected, an impermeable membrane under the walking surface is usually required, and that is a separate layer from the weed mat.
Washing has a cost the specification should anticipate. Detergent and disinfectant cycles shorten the life of light fabrics, and any cover that cannot take a pressure washer will be replaced more often than the budget assumes. The crop turnaround cleaning guide sets out what those chemicals do to floor materials.
Edging Around Beds and Paths
Every bed leg, post and doorway is a place where the mat can lift. Fixing the edge is cheaper than replacing the sheet.
- Run the mat under the bed feet rather than cutting around each one; a cut edge is a weed entry and a tear start.
- Turn up 100 to 150 mm at walls, doorways and the base of posts, and fix the turn-up to a batten or a profile.
- Use a solid edge on the main spine: a concrete haunch, a kerb, or aluminium edging strip. Fabric edge alone will not survive trolley wheels.
- Separate clean and dirty routes with a visible change of colour or a physical kerb, so the zoning survives staff turnover.
Route layout and floor specification are the same decision. The internal logistics guide on layout, routes and labour shows how aisle widths and turning circles set the traffic class the floor has to carry.
When Films Beat Woven Fabric
Smooth film wins in three situations: where runoff has to be captured rather than allowed to soak away, where a hygiene audit demands a sealed and sanitizable surface, and where the floor is washed daily. It loses on grip, on puncture resistance under point loads, and on comfort for crews standing all day.
Woven fabric wins wherever weeds are the main problem, where the base drains well, and where the floor sees mixed traffic. It is also far more forgiving of an imperfect base, which matters on retrofit jobs where the ground is never quite level.
The pattern seen on almost every floor inspection: the sheet is specified by weight, installed well, and then fails at the doorway and along the bed line within one season, because those two edges were cut to fit instead of being turned up and fixed. Order the edging profile with the mat, not after it.
Replacement planning belongs with the rest of the consumables budget. Floor cover sits in the same category as the short-life parts in the equipment lifespan guide: cheap per square metre, expensive to change during a crop, and always cheaper to replace on a planned cycle.
FAQ
What weight weed mat should a greenhouse use?
A: 100 to 130 g/m² for main walking aisles and light trolleys; 150 to 200 g/m² on routes carrying loaded trolleys or pallet trucks.
Should the floor cover drain through or shed water?
A: Drain through in growing aisles where the base drains well; shed water where runoff is collected or where a hygiene audit requires a sealed surface.
How much overlap do seams need?
A: 150 to 300 mm, laid uphill over downhill, pinned at 300 to 500 mm along the joint and stitched or welded on any surface that gets pressure-washed.
Does disinfectant shorten the life of ground cover fabric?
A: Yes. Repeated detergent and disinfectant cycles degrade light fabrics faster than UV does under cover, so choose the weight for the cleaning regime as much as for the traffic.
Can film be laid straight over soil?
A: It can, but it traps moisture and smells, and weeds root through the damp layer. A woven mat with a drainage base is the better choice unless the floor must be sealed.
Request a Floor Cover Spec Quote
Send floor area, traffic class, drainage arrangement and cleaning regime through the floor cover spec quote form and the engineering team will return a weight, weave and UV package for your greenhouse ground cover, with edging and fixing quantities calculated from the layout.
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