Every greenhouse project eventually comes down to two questions: what grows inside it, and when. The structure — span, gutter height, glazing, heating capacity, lighting and irrigation — is only worth what the crop plan allows it to earn. A greenhouse that is technically excellent but scheduled badly will sit half empty through the most expensive months of the year.
This guide sets out the framework our team uses when we design and build turnkey greenhouse projects for growers in North America and Europe: start from the market, screen crops against the climate the greenhouse can actually deliver, then build a calendar that keeps production moving every week of the year.
01 / Greenhouse first
Why the greenhouse comes before the crop
Crop selection is really a climate-control question in disguise. Every crop needs a specific combination of temperature, light, humidity and root-zone conditions, and the greenhouse is the machine that has to deliver them. Before comparing crop prices, work out what your structure can physically provide:
- Light. Glazing type, roof geometry, structural shading and your latitude determine the daily light integral (DLI) available in winter.[1] This single number decides whether fruiting crops are viable.
- Height. Gutter height caps how tall a crop can be trained. High-wire tomato and cucumber need 4.5–6 m of gutter height; a low tunnel cannot substitute for it.
- Heating capacity. The coldest night of the year sets the installed capacity, and that sets your fixed costs. A crop that tolerates 12 °C nights is far cheaper to run than one that needs 19 °C.
- Cooling and ventilation. In a European or North American summer, cooling capacity — vents, screens, fogging or mechanical cooling — decides what you can grow from June to August.
- Humidity control. Dehumidification and air movement determine disease pressure, and therefore your spray costs and crop losses.
- Irrigation and fertigation. Drip, ebb-and-flow, NFT or gutter systems are crop-specific choices that must be designed before construction, not retrofitted after.
Design principle
Design the greenhouse and the crop plan together. A turnkey project starts with the sales plan, converts it into a crop schedule, and only then specifies span, gutter height, screens, lighting and irrigation. When a greenhouse is bought first and a crop chosen later, the grower usually ends up paying for capacity they cannot use — or missing capacity they need.
The same logic explains why the most successful projects we build are not the largest ones, but the ones where the greenhouse, the crop and the sales channel were matched from the first sketch.
02 / Selection
The six criteria for selecting greenhouse crops
Growers usually choose crops by price per kilogram. That is the wrong metric for a greenhouse, because a greenhouse is a capital asset measured in square meters, not in hectares of open field. Score every candidate crop against the six criteria below.
1
Market pull
Who buys it, how often, and at what price? A crop only works if there is a repeat buyer within your distribution radius.
2
Revenue density
Revenue per m² per year — the combined effect of price, yield, crop duration and how quickly the space is re-filled.
3
Climate fit
Does the crop's temperature, light (DLI) and humidity requirement sit inside what your structure can deliver at an affordable cost?
4
Cycle length and cash flow
Short cycles mean faster cash conversion but more labour. Long cycles mean fewer, larger cash events and a longer wait for the first euro or dollar.
5
Labour and skill
High-wire tomato requires trained pruners and daily crop work. Microgreens require almost none. Match the crop to the team you can actually hire and keep.
6
Risk and resilience
How easily does the crop fail — disease, pollination, tipburn, price collapse? Vulnerable crops need either a premium margin or a diversified plan.
Start with revenue density, not price
Revenue density is the criterion that separates hobby thinking from commercial thinking. A crop sold at a high unit price but occupying the same bench for six months can generate less income per square meter than a modestly priced crop harvested eight times a year. When we model a project, we build the plan around revenue per m² per year, then check that the crop mix also covers labour peaks and gaps in supply.
A simple scoring model
Score each candidate crop from 1 to 5 against the criteria below, weight them, and rank. The weights in the table are typical for a northern heated greenhouse; adjust them for your market — a direct-to-consumer grower should raise "market pull", a wholesaler should raise "revenue density".
| Criterion | Question to answer | Typical weight |
|---|---|---|
| Market pull | Is there a committed buyer, and how stable is the price across 12 months? | 25% |
| Revenue density | What is the expected revenue per m² per year, net of crop failures? | 25% |
| Climate fit | Can the structure hold the crop's temperature, DLI and humidity setpoints economically? | 20% |
| Cycle and cash flow | How many turns per year, and how long until the first sale? | 15% |
| Labour and skill | Hours per m² per week, and the skills the crop demands. | 10% |
| Risk and resilience | Probability and cost of a lost crop; availability of crop insurance or alternative channels. | 5% |
Weighting is a planning aid, not a fixed rule. Any crop that scores below 2 on market pull or climate fit should be dropped regardless of its total.
03 / Crops
Crop profiles for northern greenhouses
The table below summarises the crops that work reliably in heated greenhouses across North America and Europe, with the climate setpoints and light targets a greenhouse must be able to hold. Treat the values as planning ranges: cultivars, local climate and market preferences all shift the numbers, and your own records should replace them within two seasons.
| Crop | Day temp | Night temp | DLI min | DLI target | Cycle to 1st harvest | Harvest window |
|---|---|---|---|---|---|---|
| Tomato (indeterminate, high-wire) | 21–24 °C | 17–19 °C | 20 | 25–30 | 65–80 days | 8–10 months |
| Cucumber (high-wire) | 23–27 °C | 17–19 °C | 20 | 25–30 | 55–70 days | 3–5 months |
| Sweet pepper | 21–25 °C | 17–19 °C | 20 | 25–28 | 70–90 days | 3–5 months |
| Strawberry (day-neutral) | 18–22 °C | 10–13 °C | 15 | 20–25 | 90–110 days | 6–9 months |
| Lettuce (head) | 18–21 °C | 10–13 °C | 12–14 | 14–18 | 30–45 days | single cut |
| Leafy greens / baby leaf | 18–22 °C | 10–14 °C | 12–14 | 14–18 | 21–35 days | cut-and-come-again |
| Basil and fresh herbs | 22–26 °C | 18–20 °C | 12–14 | 16–20 | 30–45 days | 8–12 weeks |
| Microgreens (rack) | 18–22 °C | 16–18 °C | 8 | 10–14 | 7–21 days | single cut |
DLI in mol·m⁻²·d⁻¹. Light targets follow the ranges published by Michigan State University Extension for greenhouse vegetables: a minimum of about 12–14 mol·m⁻²·d⁻¹ for lettuce, and 20 mol·m⁻²·d⁻¹ or more for vine crops.
04 / Scheduling
Building a 12-month production calendar
Selecting crops is the easy half. The harder, more valuable half is deciding when each square meter is occupied, and by what. A greenhouse schedule is a capacity plan: it tells you which zones are planted, when they are empty, and how the harvests line up with the market.
4.1 Succession planting: smooth supply instead of feast and famine
Succession planting means replanting the same crop at intervals so that harvests arrive continuously rather than in one overwhelming wave.[3][4] For a commercial greenhouse, two patterns matter:
- Interval sowing. Sow leafy crops every 10–14 days in a dedicated zone so a fixed volume of fresh product leaves the greenhouse every week. This is the pattern that keeps a restaurant or retail contract supplied.
- Sequential cropping. Follow a long-season fruiting crop with a fast catch crop. Tomato houses are often turned over to lettuce, spinach or radish for the weeks between crop destruction and replanting.[3]
4.2 Zoning: more than one climate in one greenhouse
Dividing a gutter-connected greenhouse into independent climate zones is one of the highest-return investments available, because it lets a single structure run a cool-crop regime and a warm-crop regime at the same time. A typical four-zone commercial layout looks like this:
4.3 Schedule by light, not by the calendar
Calendar dates are unreliable in a greenhouse, because plant development tracks temperature and accumulated light rather than the month. A lettuce crop transplanted on 1 November in a northern glasshouse can take twice as long as the same crop transplanted in April. Two habits solve this:
- Plan in DLI and degree-days. Convert each crop's requirement into a light and heat budget per square meter, then compare that to what your site delivers month by month.
- Build in a buffer season. In December and January, add 20–30% to expected cycle times. Crops that arrive "early" are a manageable problem; crops that arrive late lose contracts.
4.4 A worked example: a 5,000 m² heated glasshouse
The calendar below is a realistic plan for a 5,000 m² heated glasshouse in a temperate northern market, split into four production zones plus a vertical microgreens rack. It is deliberately mixed: long-season fruiting crops for revenue density, short-cycle leafy crops for cash flow, and a winter strawberry crop to capture premium off-season pricing.
| Zone | Area | Crop | Plant | First harvest | Last harvest | Turns / year |
|---|---|---|---|---|---|---|
| A — high-wire | 1,200 m² | Tomato, indeterminate | mid-Jan | late Mar | late Nov | 1 |
| B — high-wire | 1,200 m² | Cucumber, 2 crops | mid-Feb / mid-Aug | mid-Apr / early Oct | early Jul / mid-Nov | 2 |
| C — benches | 2,000 m² | Lettuce and leafy greens | continuous, every 10–14 days | 30–45 days after sowing | continuous | 6–8 |
| D — mixed | 600 m² | Strawberry (Sep–Jun), basil (Jun–Sep) | mid-Sep / Jun | Jan / 30–45 days | Jun / Sep | 1 + 1 |
| Rack — vertical | microgreens | Microgreens, 12–20 turns | weekly | 7–21 days | continuous | 12–20 |
05 / Systems
Matching greenhouse systems to the schedule
Once the crop plan is fixed, the engineering follows from it. The table below maps the main crop archetypes to the structure and equipment they require — this is the checklist we use when converting a crop schedule into a greenhouse specification.
| Crop archetype | Structure | Growing system | Key equipment |
|---|---|---|---|
| High-wire fruiting (tomato, cucumber, pepper) | Venlo or wide-span glass, gutter height 4.5–6 m, trellis wire | Grow bags or slabs on gutters, drip fertigation | Supplemental LED/HPS to reach 20+ DLI, CO₂ enrichment, pipe rail heating, dehumidification |
| Berries (day-neutral strawberry) | Glass or film, gutter height 3.5–4.5 m | Table-top gutters or raised benches, drip | Cooling and shading, pollinator management, night cooling for fruit set |
| Leafy greens and lettuce | Any glazed structure; benches, mobile gutters or multi-layer | Bench or NFT/mobile gutter, ebb-and-flow | Modest supplemental light (14–18 DLI), horizontal airflow, root-zone cooling |
| Herbs (basil, parsley, mint) | Film or glass, gutter height 3–4 m | Pots or benches, drip or ebb-and-flow | High night temperatures, supplemental light, humidity control to prevent leaf disease |
| Microgreens | Insulated room or poly house with multi-tier racks | Racks, trays, sub-irrigation | Low-light LED bars, high humidity, strict sanitation protocol |
| Transplant nursery | Dedicated propagation zone with screen and shade | Mobile benches, trays | Root-zone heating, misting, rolling benches, grafting area |
The point of the table is sequencing: the crop plan decides the system, and the system decides the structure. Reverse the order and you commit capital to equipment that does not fit the crops you end up growing.
06 / Pitfalls
Six scheduling mistakes that destroy margin
- Planting everything at once. Without interval sowing, all the labour, all the harvest and all the risk land in the same fortnight, and your buyer receives a glut followed by nothing.
- Ignoring winter light. Schedules copied from summer or from a southern climate produce crops that stall in November and January, then collide with the next planting.[1]
- One climate for the whole house. A monoculture schedule is simple, but it wastes the temperature and humidity ranges your structure could exploit — and concentrates risk.
- No sanitation window. Skipping the turnaround gap between crops to gain a few days of production usually costs more in disease pressure and lost crop quality than it earns.
- Scheduling by price peak only. Targeting the highest-price week often means harvesting into an oversupplied market, because every other grower read the same calendar.
- Never comparing plan to actual. A schedule is a forecast. Without weekly records of actual sow, transplant, first-harvest and crop-end dates, the plan cannot be corrected and the same bottleneck repeats every season.
07 / FAQ
Frequently asked questions
What are the most profitable crops to grow in a greenhouse?
Profit is driven by revenue per m² per year, not by price per kilogram. In heated North American and European greenhouses, high-wire tomatoes, cucumbers, sweet peppers and day-neutral strawberries typically deliver the highest revenue density, because they occupy the space for most of the year and command premium off-season prices. Leafy greens, herbs and microgreens are usually lower revenue per square meter but win on turnover speed, lower capital cost per turn and much shorter payback on a small area.
How many crops can you grow in a greenhouse in one year?
It depends entirely on cycle length. A long-season fruiting crop such as high-wire tomato is normally grown as a single turn per year, while cucumber works well as two crops. Bench-grown lettuce and leafy greens turn over 5 to 8 times a year, herbs 4 to 6 times, and rack-grown microgreens 12 to 20 times. Mixing a long-cycle crop with a short-cycle crop is the standard way to balance cash flow.
Do I need supplemental lighting to grow year-round?
In northern latitudes, yes for most fruiting crops. Lettuce and leafy greens need a minimum of roughly 12–14 mol·m⁻²·d⁻¹, while tomato and cucumber need about 20 mol·m⁻²·d⁻¹ or more.[1] Winter natural light alone rarely reaches those levels, so supplemental LED or HPS lighting is what makes a genuine 12-month schedule possible. Lighting should be sized during design, because it affects electrical capacity, screens and structure loading.
Should I use a high-wire system or bench and gutter systems?
Use high-wire for tall, long-season fruiting crops such as tomato and cucumber: it converts gutter height into additional yield, which is why these crops are grown in 4.5–6 m structures. Use benches, mobile gutters or racks for short-cycle crops such as lettuce, leafy greens, herbs and microgreens, where fast turnaround, easy mechanization and multi-layer production matter more than vertical growth.
What greenhouse size makes sense for commercial production?
Most commercial vegetable greenhouses start at roughly 2,000–5,000 m² and expand in modules. The real minimum is set by your sales channel and labour model: a wholesale programme needs enough continuous volume to fill a load, while a restaurant or direct-to-consumer programme can start smaller with a higher-margin, more diverse crop mix.
How far ahead should I plan planting dates?
Plan the whole year before the first seed goes in. Work backwards from your target sales windows using days to first harvest and total crop duration, then place transplant dates and sanitation gaps. Succession sowings of leafy crops should be scheduled every 10–14 days so supply stays level.[4]
Is a heated greenhouse worth it in cold climates?
It depends on crop value, and the answer is a cost-per-square-meter calculation. Heating a northern greenhouse through winter to produce lettuce is rarely economic; heating the same structure to keep a high-wire tomato crop productive often is. The crop plan, not the heating system, decides.
Can different crops share one greenhouse?
Yes — and it is usually the better commercial decision. Dividing a gutter-connected house into independent climate zones lets you run cool crops and warm crops simultaneously, spread labour peaks across the year, and avoid putting your entire revenue into one crop. Zoning is typically far cheaper than building a second structure.
08 / Summary
Key takeaways
- Design the greenhouse around the crop plan. Span, gutter height, glazing, lighting and irrigation are downstream of what you intend to grow and sell.
- Score crops on revenue density, not unit price. Revenue per m² per year is the metric that pays for the structure.
- Check the climate fit before signing the crop. Temperature windows of 10–13 °C at night are much cheaper than 17–19 °C, and winter DLI decides whether fruiting crops are viable at all.
- Build the calendar before the first sowing. Succession sow every 10–14 days, zone the house, and add a 20–30% buffer to winter cycle times.
- Always keep one fast-turnover crop. It is your shock absorber, your cash-flow engine and your hedge against a season going wrong.
- Compare plan against actuals weekly. A schedule is only useful if it is corrected every season.
Next step
Planning a greenhouse? Start with the crop plan.
[Your Company] designs and builds turnkey commercial greenhouses — structure, climate control, irrigation and lighting — around the crops you intend to grow and the customers you intend to supply.
- A 30-minute review of your crop plan and market windows
- Zone-by-zone scheduling templates and climate setpoints
- Indicative structure and equipment specification, sized to your schedule
