How much capacity do you gain by switching to double-row production?

16 September 2026

Switching to double-row production on a potting line can realistically double your output, moving from a typical single-row capacity of around 3,000 to 4,000 pots per hour to as many as 8,000 pots per hour on a well-configured double-row setup. The exact gain depends on your pot size, growing mix, and how well the rest of your line keeps up. Below, we break down exactly what that shift looks like in practice and how to decide whether it makes sense for your operation.

What does double-row production actually mean on a potting line?

Double-row production means your potting machine fills two rows of pots simultaneously in a single pass, rather than one. Instead of one pot being drilled, filled, and released at a time, two pots move through the cycle in parallel, effectively running two production lanes through one machine. This is not simply running the machine faster; it is a structural change in how output is generated.

On a single-row setup, the conveyor carries pots in a single line from the filling station onward. On a double-row setup, pots are positioned side by side, and the machine’s drilling and filling mechanisms are configured to serve both positions at the same time. The downstream transport, trays, conveyors, sorting lines, needs to be matched to handle the wider or faster flow of pots coming off the machine.

This matters because it changes the rhythm of the entire line, not just the potting machine itself. A double-row configuration is not an add-on setting you flip at the start of the day; it is a deliberate production choice that affects staffing positions, conveyor speed, and how you handle trays or trolleys at the end of the line.

How much faster is double-row potting compared to single-row?

In practical terms, double-row potting can deliver close to twice the pots per hour compared to single-row, but the real-world gain is typically between 70% and 100% more output, not always a perfect doubling. The machine cycle time per row remains roughly the same, but because two pots are completed per cycle instead of one, throughput rises sharply without requiring a proportional increase in machine speed.

To put this in concrete terms: a machine running single-row at 4,000 pots per hour can often reach 7,000 to 8,000 pots per hour in double-row mode, depending on pot size and growing mix consistency. Smaller pots, say 9 cm or 10.5 cm, tend to see the biggest proportional gains because the machine cycles quickly and the volume per pot is low. Larger pots introduce more filling time per cycle, which narrows the gap slightly.

The key point is that the speed increase comes from parallel processing, not from running the machine harder. That means wear and noise levels do not increase proportionally, a significant advantage during long production days.

What factors determine how much capacity you actually gain?

The capacity gain from double-row potting is real, but it is not identical for every grower. Several factors shape how much of that theoretical doubling you actually see in practice.

Pot size: Smaller pots fill faster and move more easily in parallel. Larger pots require more soil volume per cycle, which can slow the overall rhythm and reduce the gap between single- and double-row output.
Growing mix quality and consistency: A mix that flows freely and fills evenly allows the machine to run at full speed. Coarser or heavier mixes create resistance that can slow filling time or cause variation between the two rows.
Conveyor and downstream line capacity: If your transport system cannot handle the higher volume of pots coming off the machine, the bottleneck simply moves downstream. Double-row output requires conveyor systems that are matched to the increased flow.
Staffing at the end of the line: More pots per hour means more pots to place on trolleys or trays. If you do not adjust the staffing or automation at the output end, the gain on the machine side gets absorbed by a backlog further down.
Machine configuration and calibration: Both rows need to be drilled and filled to the same depth and density. If calibration is off, one row may produce inconsistent pots, which creates quality issues rather than a clean capacity gain.

Does switching to double-row also reduce labor costs?

Yes, switching to double-row production typically reduces the labor cost per pot, even if the total number of people on the line stays the same. Because you are producing significantly more pots in the same working hours, the labor input per 1,000 pots drops. In practice, many growers find they can maintain or even reduce headcount while increasing total output, particularly when the double-row setup is part of a more fully automated line.

The labor savings show up most clearly in two places. First, at the potting machine itself: one operator can oversee a double-row machine just as easily as a single-row machine. The machine does more work without requiring a second operator at the filling station. Second, the efficiency gain often justifies automating adjacent steps, such as tray handling or pot placement, that previously relied on manual labor because the volume did not warrant it.

That said, the labor equation only works in your favor if the rest of the line is set up to handle the volume. If the output end of the line becomes a bottleneck, you may need to add a person there, partially offsetting the savings at the machine. A well-integrated line design is what turns a capacity gain into a genuine cost-per-pot reduction.

When does upgrading to a double-row potting machine make sense?

Upgrading to a double-row potting machine makes sense when your current output is consistently the bottleneck in your production process, particularly during seasonal peaks when every hour of lost capacity has a direct commercial cost. If your team is already working at maximum pace on a single-row machine and you are still falling short of targets, adding speed to a single-row setup has limited upside. A double-row configuration changes the ceiling, not just the pace.

Other strong signals that double-row is the right move include:

You are regularly turning down volume or cutting product ranges because you cannot pot fast enough.
You are running the machine for extended hours to compensate for lower throughput, increasing wear and fatigue.
Your labor costs per pot are high because a relatively slow machine requires a proportionally large team to keep up.
You are already running a modern conveyor and sorting line that can absorb higher output without modification.
You are potting primarily in smaller pot sizes (7 to 15 cm), where double-row gains are most pronounced.

If your operation is smaller or your volumes are inconsistent across the year, a single-row machine at high efficiency may still be the better fit. The investment in a double-row setup pays off most clearly when you have the consistent volume to keep it running near capacity.

How the Stolze 3030 supports double-row potting

Our Stolze 3030 is built to run single-, double-, or alternating-row configurations, giving you the flexibility to match production mode to your daily volume without swapping machines. For growers who want to push further, the Stolze 3030 PRO adds automatic soil detection, a fully guided chain for greater stability across both rows, and programmable touchscreen menus for different pot sizes and drilling depths. Together, these features ensure that both rows fill consistently and at the same density, which is what turns a theoretical capacity gain into reliable output you can count on.

Capacity up to 8,000 pots per hour in double-row mode
Suitable for pots from 7 to 30 cm
Seamless integration with conveyors, topping machines, and sorting lines
Available to buy or rent, including a trial period
Supported by our own technicians from installation through daily use

Curious whether double-row production is the right step for your operation? Get in touch with us and we will help you work through the numbers for your specific pot sizes, volumes, and line setup.

Frequently Asked Questions

Can I retrofit my existing single-row potting machine to run double-row, or do I need a new machine?

In most cases, retrofitting a single-row machine to true double-row production is not straightforward, as it requires structural changes to the drilling and filling mechanisms, not just a conveyor adjustment. Most older single-row machines were not engineered with the frame width or drive capacity to support parallel row processing. If your current machine is relatively modern and the manufacturer offers a double-row upgrade kit, it is worth asking, but for the majority of growers, the step up to double-row means investing in a machine purpose-built for it.

What conveyor setup do I need to handle double-row output without creating a downstream bottleneck?

At 7,000 to 8,000 pots per hour, your conveyor system needs to be both wide enough and fast enough to transport two rows of pots away from the machine without pots backing up or tipping. This typically means upgrading to wider belt conveyors or adding a second parallel transport lane, depending on your current layout. It is also worth reviewing the capacity of any sorting, tray-loading, or trolley-filling stations downstream, as these are the most common points where the bottleneck shifts once the machine output increases.

How do I make sure both rows are filled consistently and to the same quality standard?

Consistent filling across both rows comes down to proper machine calibration and growing mix quality. Both drilling heads need to be set to the same depth and the filling mechanism must distribute soil evenly to both positions per cycle. Running a coarser or poorly mixed substrate increases the risk of variation between rows, so it is worth checking your mix consistency before switching to double-row mode. On machines like the Stolze 3030 PRO, automatic soil detection helps compensate for minor mix variations and flags inconsistencies before they become a quality problem.

How long does it typically take to recoup the investment in a double-row potting machine?

The payback period depends heavily on your annual volume, pot sizes, and current labor costs, but growers running consistent seasonal volumes in smaller pot sizes (7–15 cm) often see the investment pay back within one to three growing seasons. The clearest gains come from the combination of higher throughput and lower labor cost per pot, particularly when the double-row setup allows you to reduce overtime hours or reallocate staff. Running a simple cost-per-pot calculation for your current setup versus projected double-row output is the most reliable way to estimate your specific payback window.

What happens if I only need double-row output during peak season — is it practical to switch between modes?

Yes, this is one of the practical advantages of machines designed for multi-row flexibility, such as the Stolze 3030, which supports single-, double-, and alternating-row configurations. Switching between modes requires reconfiguring the machine and adjusting your downstream line, so it is not something you would do mid-shift, but it is absolutely manageable as a seasonal or weekly production decision. If your volume is highly variable across the year, this flexibility can make a double-row-capable machine a better investment than a fixed single-row setup, since you are not locked into one output level.

What are the most common mistakes growers make when first running double-row production?

The most frequent mistake is upgrading the potting machine without simultaneously preparing the rest of the line for the increased output, leading to a bottleneck at the tray-loading or trolley-filling stage that erases much of the capacity gain. A close second is underestimating the importance of growing mix consistency; a mix that performed adequately on a single-row machine can cause uneven filling or cycle interruptions when the machine is processing two rows simultaneously. Taking the time to calibrate both rows individually before going into full production, and running a short test batch to verify fill depth and density across both positions, will save significant troubleshooting time later.

Is double-row potting suitable for larger pot sizes, or is it mainly beneficial for small pots?

Double-row potting works across a wide range of pot sizes, but the proportional capacity gain is most pronounced with smaller pots in the 7–15 cm range, where fast cycle times and low soil volume per pot allow both rows to run at full rhythm. With larger pots, say 19 cm and above, the increased soil volume per cycle slightly slows the overall pace, which narrows the gap between single- and double-row output. That said, even with larger pots, double-row production still delivers a meaningful throughput increase over single-row, and for growers working with mixed pot size ranges, a machine that handles both small and large pots in double-row mode offers the best of both worlds.

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