Greenhouse & Nursery Drainage

Q: How do I stop algae on greenhouse walkways?

Algae needs standing moisture, so the cure is getting irrigation water off the surface fast. Run a low-profile channel drain along the walkway low line or across aisle intersections, keep the grates clear of potting media, and the film never gets a chance to establish. Drier walkways also mean fewer fungus gnats and less disease pressure at bench level.

Q: How big should drainage be for a greenhouse or container yard?

Size it from real numbers, not guesswork: greenhouse roofs shed their entire footprint of rain to the eave lines, and container yards add daily irrigation on top of storms. Run your covered area and yard area through our runoff calculator, then match channel and basin capacity to the result.

Drainage by Application · Greenhouses & Nurseries

In a greenhouse, "rain" happens every day on a schedule. Irrigation overspray, bench drip, flood-floor cycles, and container-yard runoff all have to leave the floor fast — or you grow algae, disease, and mud alongside the crop.

Why growers spec drainage differently

A storm drain waits for weather; greenhouse drainage works every day. Overhead watering and flood floors leave sheets of water on slabs and walkways, and whatever stands becomes an algae film — a slip hazard for the crew and a nursery for fungus gnats and root disease. Outside, gravel container yards take irrigation on top of every storm and churn to mud exactly where carts and customers travel. And the water itself is not clean: fertigation runoff carries fertilizer salts that attack bare metal year after year. The answer is fast, continuous collection with materials chosen for the chemistry.

Load classes around a growing operation

Walkways and bench aisles are pedestrian surfaces (Class A). Anywhere pallet jacks, carts, or small loaders travel, step up to Class B, and give delivery lanes that see box trucks a Class C rating. Match every run to its traffic with our Load Class Recommendation Guide before picking grates.

Recommended systems

Greenhouse walkways & bench aisles

NDS Mini Channel is the walkway standard: a low-profile channel that sets into a thin slab, swallows irrigation overspray at the aisle low line, and clears out easily when potting media washes in. For the tightest slabs, NDS Micro Channel does the same job in a 1.25-inch width. Both are available to order online.

NDS Mini Channel drain installed flush in a concrete slab walkway — NDS Mini Channel set flush in a slab — the low-profile walkway workhorse.

Headhouse slabs, perimeters & hoop-house edges

Where roof runoff concentrates along eave lines or a headhouse slab collects wash water, NDS Spee-D Channel is the economical perimeter pick, and NDS Pro Series covers wider or busier slabs with 3- to 12-inch channel widths and grate options to match the traffic.

Fertigation, dosing & mixing areas

Where fertilizer concentrate and chemicals are handled, channel material matters most. BG Filcoten trench drain is fiber-reinforced concrete that resists the fertilizer- and chemical-laden water a dosing area sheds — see the Filcoten FAQs & resources for the material story and channel lineup.

Container yards & outdoor pads

Catch basins collect yard runoff at low points before it cuts channels through the gravel; buried pipe carries it to daylight through pop-up emitters, or into dry wells where there is no downslope outlet. Yards that drain between cycles stay firm under carts and customers.

Planning tip: a greenhouse roof delivers its entire footprint of rain to the eave lines, and irrigation adds daily volume storms never account for. Run your covered and yard areas through the runoff calculator before sizing channels and basins.

Supporting resources

Load Class Recommendation Guide — aisles, cart lanes, and delivery drives rated right
NDS Mini Channel FAQs & resources — the walkway channel, explained
NDS Spee-D Channel FAQs & resources — the perimeter economical pick
Filcoten trench drain FAQs & resources — fiber-reinforced concrete for chemical areas
Sizing for storms: estimating runoff — what your roofs and yards actually shed
Runoff calculator — quick sizing from area and rainfall

Frequently asked questions

How do I stop algae on greenhouse walkways?

Algae needs standing moisture — get irrigation water off the surface fast with a channel along the walkway low line, and keep grates clear of potting media. Drier walkways also mean fewer fungus gnats and less disease pressure at bench level.

Will fertilizer water corrode a channel drain?

Constant fertigation runoff is hard on bare metal. Polymer channels like the NDS lines and fiber-reinforced concrete like Filcoten resist fertilizer salts well — and pick the grate material with the same chemistry in mind.

How big should drainage be for a greenhouse or container yard?

Size from real numbers: roofs shed their whole footprint to the eaves, and irrigation adds daily volume. Run your areas through the runoff calculator and match channel and basin capacity to the result.