Value Stream Mapping for Greenhouse Horticulture and Protected Cropping: From Seedling Transplant to Packed Punnet Without the Harvest Glut

Why map the value stream in protected cropping?

A greenhouse crop can be healthy, ripe and ready to pick, and still miss the customer’s order window. Harvest timing, labour availability, transport, cooling slots and packhouse capacity all need to align. If they do not, punnets wait, quality life is consumed in queues, and the operation may harvest more than it can pack or sell.

Value stream mapping (VSM) makes the full flow visible: material moves from transplant through cultivation, harvest, cooling, grading, packing and dispatch, while information moves from customer orders and crop forecasts back to the growing and operations teams. Mapping both flows helps identify where customer value is created, where work accumulates, and how to coordinate release with real capacity.

The figures below form an illustrative worked example, not a universal industry benchmark or site-specific result. Crop, cultivar, climate, packaging, customer specifications and cooling requirements vary. A New Zealand glasshouse tomato study, for example, found that unharvested crop accounted for most of the measured loss: an important reminder to investigate harvest release and demand alignment, not only packhouse rejects. Read the study.

1. Select the value stream and set clear boundaries

Map one product family and one customer channel first. Here, the example is 250 g greenhouse tomato punnets for a retail customer.

• Customer: retail distribution centre receiving the packed punnets.
• Start: seedling transplant into the production block.
• Finish: packed, labelled and dispatched order.
• Demand: 4,000 punnets per day, or 1,000 kg/day.
• Available packhouse time: 420 minutes per day, after planned breaks and cleaning.

The transplant-to-first-harvest period is included to show the full crop stream, but it is not equivalent to a queue. Biological growing time is essential process time; the improvement opportunity is to plan the crop and harvest to demand while reducing avoidable waits after picking.

2. Current state: trace the crop, the information and the waiting

The table shows an illustrative daily flow during a representative harvest period. Cycle time is active time at a step or the relevant run rate; queue time is elapsed waiting before the next operation. WIP is a point-in-time estimate. Harvest windows and capacity should be verified across peak and quieter days.

At 4,000 punnets, the pack line needs about 6.1 run hours at 660 punnets per hour. Despite sufficient average line rate in this example, uneven arrivals and cooling-slot availability create queues that consume shelf life. From harvest completion through dispatch, the listed queues, processing and transfer add roughly 12 hours; actual elapsed time will vary with overlap between operations and the dispatch schedule.

Rolled throughput yield and perishable shrink

For a simple yield waterfall, assume the lot passes three quality gates:

• Harvest condition: 96%
• Receiving condition: 98%
• Grading and packing: 96%

Rolled throughput yield (RTY) is the product of the first-pass yields:
0.96 × 0.98 × 0.96 = 90.3%

Applied to 1,150 kg harvested, that is approximately 1,038 kg of saleable product, or about 4,152 punnets at 250 g each. The implied loss from harvested weight to saleable packed product is 9.7% in this model. Record actual rejects, downgrades, damage and decay separately; a single shrink figure will not reveal which countermeasure is needed.

3. Identify the eight wastes with DOWNTIME

Use the DOWNTIME framework at the gemba, walking the process and speaking with the people doing the work, to make waste specific and observable.

1. Defects: soft, damaged or incorrectly graded fruit; label or weight errors requiring rework.
2. Overproduction: picking beyond confirmed demand, safe buffer limits or available cooling and packing capacity.
3. Waiting: picked fruit waiting for collection, receiving, cooling slots, grading or dispatch.
4. Non-utilisation of talent: pickers and packers seeing recurring flow problems without a routine way to propose or test improvements.
5. Transportation: repeated tote movements or long routes between blocks, receiving and cooling.
6. Inventory: excess harvested fruit, cooling-room queues and finished punnets held beyond the dispatch plan.
7. Motion: searching for labels, tools, empty totes or the correct lot paperwork.
8. Extra processing: duplicate checks, repeated handling, unnecessary sorting or repacking that does not improve customer value.

For perishable crops, waiting and inventory are especially important because they use both operational capacity and remaining quality life. Research on blueberry logistics has documented temperature disruptions and delays in early cold-chain steps; the crop and conditions differ, but the lesson is relevant: measure time and temperature together. Read the blueberry supply-chain study.

4. Build the future state around demand and the constraint

Begin with takt time, the available production time divided by customer demand:

420 minutes × 60 ÷ 4,000 punnets = 6.3 seconds per punnet, or approximately 571 punnets per hour over the available production window.

This is the required good-output pace, not a command to run every operation continuously. Build a schedule that protects quality and avoids sending more crop into the system than the constraint can handle.

Practical future-state countermeasures

• Level harvesting: convert confirmed orders, maturity checks and expected yield into block-level harvest quantities and time slots. Release smaller lots at regular intervals rather than one large morning wave.
• Use pull signals: let the packhouse’s available cooling and line capacity trigger the next harvest release. Signal with a shared schedule, visual board or digital status, not informal assumptions.
• Book cooling before picking: reserve capacity by crop lot and customer priority. Follow the crop- and customer-approved temperature specification, and monitor lot age and pulp temperature.
• Balance the pack line: measure grading, weighing, punnet filling, labelling and case packing separately. Set staffing and standard work so the slowest task does not interrupt the rest of the line. A planned gross rate of about 630 punnets/hour at 95% availability yields roughly 599 punnets/hour, above the 571-punnet takt requirement.
• Set WIP limits and FIFO: mark lanes by lot and harvest time; make the oldest suitable lot visible. Cap buffers using observed cooling and packing capacity rather than convenience.
• Reconcile yield daily: connect greenhouse harvest weights to received, cooled, graded, packed and dispatched quantities. Pareto the loss causes and assign an owner to the leading opportunity.

5. Compare the current and target states

These future-state values are pilot targets for the illustrative scenario, not promised results. Establish the baseline and confirm targets with crop, quality, food-safety and customer teams before implementation.

The target RTY would make about 1,093 kg saleable from 1,150 kg, equivalent to approximately 4,372 punnets. The daily order remains the pacing signal; any buffer above demand should be justified by forecast, shelf-life and customer rules.

6. Sequence kaizen over 90 days

Days 1–30: See and stabilise

• Select one crop block, pack format and customer route.
• Observe normal and peak days; timestamp harvest, hand-offs, cooling, packing and dispatch.
• Confirm takt, cycle times, WIP, temperature records, first-pass yields and shrink categories.
• Create the current-state map and agree on safety, quality and service guardrails.

Days 31–60: Pilot the flow

• Trial time-slotted harvest releases and cooling reservations on one block or shift.
• Mark FIFO lanes and set temporary WIP limits.
• Balance work at the constraint and test the revised standard work.
• Review a short daily dashboard: order attainment, harvest-to-cool time, queue age, RTY, shrink and on-time dispatch.

Days 61–90: Verify and sustain

• Compare pilot results with the baseline across both typical and peak conditions.
• Adjust the release rules, staffing plan and buffer limits using observed data.
• Document ownership, escalation triggers and a weekly review routine.
• Expand only when quality, food safety, customer service and the performance gains are sustained.

Turn the map into measurable improvement

VSM is most useful when it leads to tested changes, not merely a diagram. Lean Six Sigma provides a structured way to define the problem, measure the flow, analyse root causes, improve the process and control the gains. Explore CSSC-accredited Lean Six Sigma courses, including Green Belt training for leading improvement projects and Black Belt training for complex, cross-functional change.

Choose a Green Belt or Black Belt certification and build the skills to map, measure and improve a real value stream.

Kaizen. Kai-Care. Kai-Done. Lean Six Sigma