Spray Stakes and Per-Pot Emitters for Container Nurseries: How to Size and Lay Out a Block

A container block waters evenly when the emitter type, the flow per pot and the lateral layout were worked out together before the first stake went in. This guide walks through that method in the order a grower meets it: what to measure on the block, how to pick between a spray stake, an on-line dripper, a dribble ring and a multi-outlet assembly, how to set a flow per pot so a whole zone finishes at the same time, when pressure compensation and anti-drain earn their cost, and how to zone and filter so the last pot gets the same water as the first.

By the end you should have a parts list and a flow total to bring to us for a quote. The examples use the Netafim, Primerus, Dramm, Rivulis, Antelco, Tavlit and Maxijet lines.

Measure the block before you pick an emitter

Four numbers decide most of the sizing, and none of them are on an emitter spec sheet. Collect them for every bed before you look at products.

First, the container inventory: how many pots of each size, and whether each bed holds one size or several. Pot size sets the flow per point and the delivery type, and mixing sizes on one lateral is the root of most uneven blocks.

Second, run length and grade. Measure the longest lateral from the sub-main to the last pot, and the fall across it. A short flat run and a long run dropping down a hillside are different problems, solved with different drippers.

Third, pressure and flow at the far end of the block under load, not at the pump. An economical non-PC stake is a sound choice where pressure across the block is already steady; it is the wrong choice where the far end sags once every zone upstream is running.

Fourth, water quality. Pond and surface water carry algae and silt, and wells can carry sand. That decides the filter, and whether you want an emitter with a wide flow path that passes debris or one that comes apart for cleaning.

Write these down. The rest of the method assumes you have them.

Choose the delivery type by container and media

Container size and media drive the choice between four ways of putting water in a pot.

Spray stakes suit containers with enough surface to wet. A fixed-pattern stake like the Primerus Spot-Spitter puts water where the root ball is rather than across the whole pot surface, and comes in standard, Spot-Spitter Tall and Spot-Spitter DownSpray patterns: Tall for larger containers and deeper canopies, DownSpray to keep water off foliage and inside the pot. Netafim's spray stakes angle the pattern downward so water lands on the mix instead of over the rim; single spray suits a stake at the pot edge, double wets more of the mix from the center.

On-line drippers suit smaller pots and tight spacing where a spray would overshoot. The Netafim Woodpecker and Button drippers, Dramm's PCAS emitters and Antelco's PC drippers together run from about 0.5 to 3 gph per point, the right order for a small container.

Dribble rings suit large containers and coarse bark, where a single drip point channels straight down and leaves the rest of the root ball dry. Dramm's Pressure Compensated Dribble Ring comes on 12 to 48 in. tubes, with the S3ANCHOR stake to hold it in place.

Multi-outlet assemblies feed several pots from one dripper. The Netafim Flat 4-Way Multi-Outlet Dripper Assembly runs one 2.11 gph WPC Jr. dripper into four tubes, and Dramm's MAN4 4 Way Manifold splits one dripper feed four ways. They pay off in dense beds of small pots. The full lines are under spray stakes and emitters and multi-outlet drippers.

Set the flow per pot so the zone finishes together

The rule is one flow per zone, matched to the pot size on that zone, with run time doing the rest. Every pot on a valve gets the same minutes, so the only way to give a larger pot more water than a smaller one on the same valve is a higher-flow emitter, not a longer cycle.

Work it from the pot up. Decide how much water a pot of that size needs per cycle, pick the emitter flow that delivers it in a run time you can live with, multiply flow by pot count for the zone total, and check that total against what the supply delivers at the emitter's working pressure.

The lines give fixed steps. Netafim PC Spray Stakes come in 3.2, 6.6, 7.9 and 10.6 gph and the non-PC Spray Stakes in 3, 5 and 7 gph. Woodpecker PC drippers step 0.53, 1.06 and 2.25 gph; Dramm PCAS emitters step 2, 4, 8 and 12 lph, which is 0.5 to 3 gph; the Rivulis E800 runs 2 to 14 l/h. On a Netafim 4-way MODS the 2.11 gph dripper is shared by four pots, roughly half a gallon per hour each.

Where a bed carries two pot sizes you cannot separate, color-coded flow steps let you fit the higher flow on the larger pots and keep one run time. Antelco's Shrubbler changes flow and coverage at its click-indexed cap, and the PotStream is likewise tuned per plant, useful on a mixed bench and a liability where crews walk the block twisting caps.

PC or non-PC, run length and anti-drain on slopes

A non-PC emitter passes more water where pressure is higher. On a short, flat, regulated lateral the difference is small and the non-PC stake or dripper is a sound choice. The limit is run length: Netafim rates its non-PC spray stakes at 215 ft on 0.520 in. pipe at 3 gph, against 145 ft at 7 gph. The more each stake takes, the faster pressure falls along the pipe and the shorter the run.

A pressure-compensating emitter holds its flow across a range, so the first and last pot on a long or sloping run get the same water. The Netafim Woodpecker PC compensates from 7 to 58 psi, and the PC Spray Stakes hold flow up to 60 psi. Every emitter also has a floor: the non-PC Rivulis ClickTif wants at least 14.5 psi. Once a run passes the non-PC length for its flow, the block has real fall, or the far-end reading from step one is soft, go PC.

Anti-drain is the second question on a slope. When a zone shuts off, a plain lateral empties through its lowest emitters, so the bottom pots get an extra dose every cycle and the next cycle starts by refilling pipe. The Netafim WPC-CNL seals once pressure drops below 2.17 psi, about 5 ft of head. The smaller WPCJ seals at 1.7 psi, about 3.9 ft, and starts compensating at 10.2 psi rather than 14.5, so it suits shallower slopes and lower-pressure systems. The Rivulis Supertif PCND and the CNL form of Netafim's PCJ On-Line Dripper do the same job.

Zone, size the laterals and build the head end

Zone by pot size first and by crop second. Every pot on a valve shares a run time, so a zone should hold one container size, or sizes close enough that one emitter flow step covers the gap. A valve that mixes liners with large shrubs will never water evenly whatever the emitters cost.

Then count. Pots per lateral times emitter flow gives the lateral flow; laterals per zone times that gives the zone flow; that figure has to sit inside what the supply delivers at the emitter's working pressure. If it does not, split the zone or drop a flow step and run longer.

Keep laterals serviceable. Dramm's Easyloc 16 mm fittings and inline valves shut a single run without a clamp, a Figure 8 Clamp closes the end, and the 1/4 in Microvalve turns off an individual PC dripper. Netafim's Multi-Outlet Dripper Assembly Components, replacement drippers, arrow drippers, tubing and stakes, mean a MODS bed is repaired rather than replaced.

Filtration is set by the water, not the emitter. Netafim recommends 120 mesh for the non-PC Woodpecker and Button drippers; Dramm's PCAS body uses a wider labyrinth to let debris through; Antelco's CETA PC Take-Apart comes apart for cleaning and Dramm's Easyclean 45 deg. Angle Labyrinth Stake unthreads to clear algae. None of that replaces a filter sized to the source, which is covered under Filtration. Regulate pressure into the emitters' range with a pressure regulator and check it at the far end of the block, not at the valve.

The mistakes that make a block uneven

The faults behind most uneven blocks, with the fix.

• Mixed pot sizes on one valve. Split the zone, or fit the higher flow step on the larger pots.
• Non-PC past its run length. The far pots starve. Shorten the run, drop a flow step or move to PC.
• No anti-drain on a slope. The low end drowns between cycles. Fit a CNL or no-drain dripper.
• Stake aimed at the pot wall. Netafim's note applies to every brand: water that hits the wall runs out the bottom without wetting anything. Edge stakes point in; double-spray stakes sit in the center.
• Stakes that walk. A stake kicked loose waters the gravel. Tavlit's Drip Spike anchors the tube, Antelco's Asta Drip Spike PC builds the spike into the emitter, and the S3ANCHOR holds a dribble ring.
• Emitters running into gaps. Shut them off rather than pull them: Dramm's 1/4 in Microvalve, or the crimp hole on some Maxijet 13 in. stakes.
• Canopy over a short stake. Spot-Spitter Tall or DownSpray clears the foliage; Maxijet stakes also come in a tall 13 in.
• Uneven MODS tubes. Tubes of very different lengths split the dripper unevenly. Netafim's Flat 4-Way comes in standard (4 equal) and short (2 + 2 staggered) builds.
• Fine flow paths on dirty water. Filter to the emitter's rating, or choose a take-apart or wide-path design.

With the inventory, run lengths, fall and far-end pressure in hand, request a quote and ask us about the zoning. We are in Fountain Inn, South Carolina, and ship to growers in all 50 states.