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Greenhouse plant spacing chart

The short answer

Greenhouse tomatoes need 4 to 6 square feet per plant when string trained, which is roughly twice the outdoor spacing, because still air under cover makes disease pressure the limiting factor rather than light. A 4 by 8 ft greenhouse bed holds 6 to 8 tomato plants, 32 lettuce, or 96 radishes.

Crops listed
26
Tomatoes
4 to 6 sq ft each
Lettuce
8 to 10 in centers
Rule
Wider than outdoors

Researched from published specifications and verified owner reviews · Updated 2026-08-16

Greenhouse spacing is consistently wider than outdoor spacing for the same crop, and the reason is not light, it is air. Outdoors, wind moves through a canopy constantly and dries leaf surfaces within minutes of dew forming. Under cover, air is still unless you make it move, and a saturated boundary layer sitting on a leaf overnight is the precondition for botrytis, downy mildew and powdery mildew.

The practical consequence is that a greenhouse bed planted at seed-packet spacing will produce a dense, humid canopy that grows well for six weeks and then collapses into disease. Plant wider than the packet says, and run a circulation fan, and the same bed produces more total food because nothing is lost.

Figure 1. Greenhouse spacing by crop · 26 rows
Figure 1. Greenhouse spacing by crop
CropIn-row spacingRow spacingSq ft per plantPlants per 4 x 8 bedOutdoor spacing for comparison
Tomatoes, indeterminate, string trained 16 to 20 in 30 to 36 in 4 to 6 6 to 8 24 in x 36 in
Tomatoes, determinate 18 to 24 in 30 in 4 to 5 7 to 8 24 in x 30 in
Peppers 14 to 18 in 24 to 30 in 2.5 to 3.5 10 to 12 18 in x 24 in
Eggplant 18 to 24 in 30 in 4 to 5 7 to 8 24 in x 30 in
Cucumbers, vertically trained 12 to 16 in 36 in 3 to 4 8 to 10 12 in in rows 60 in apart
Melons, vertically trained 18 to 24 in 36 in 4.5 to 6 5 to 7 36 in x 60 in
Summer squash 24 to 30 in 36 in 6 to 7.5 4 to 5 24 in x 36 in
Green beans, pole 6 to 8 in 24 to 30 in 1 to 1.7 20 to 32 4 in in rows 30 in apart
Peas 3 to 4 in 18 to 24 in 0.4 to 0.7 48 to 80 2 in in rows 24 in apart
Strawberries 12 to 14 in 18 in 1.5 to 1.75 18 to 21 12 in x 24 in
Lettuce, head 10 to 12 in 12 in 0.85 to 1 32 to 38 10 in x 12 in
Lettuce, cut and come again 4 to 6 in 6 in 0.17 to 0.25 128 to 190 4 in broadcast
Spinach 4 to 6 in 8 in 0.22 to 0.33 96 to 145 3 in in rows 12 in apart
Kale 12 to 16 in 18 in 1.5 to 2 16 to 21 12 in x 18 in
Swiss chard 10 to 12 in 18 in 1.25 to 1.5 21 to 26 8 in x 18 in
Arugula 3 to 4 in 6 in 0.13 to 0.17 190 to 250 2 in broadcast
Bok choy 8 to 10 in 12 in 0.67 to 0.85 38 to 48 6 in x 12 in
Radishes 2 to 3 in 6 in 0.08 to 0.13 250 to 400 1 in in rows 4 in apart
Carrots 2 to 3 in 8 in 0.11 to 0.17 190 to 290 2 in in rows 12 in apart
Beets 3 to 4 in 8 in 0.17 to 0.22 145 to 190 3 in in rows 12 in apart
Scallions 1 to 2 in 6 in 0.04 to 0.08 400 to 800 1 in in rows 6 in apart
Basil 10 to 12 in 14 in 1 to 1.2 27 to 32 10 in x 12 in
Cilantro 4 to 6 in 8 in 0.22 to 0.33 96 to 145 4 in broadcast
Parsley 8 to 10 in 12 in 0.67 to 0.85 38 to 48 8 in x 12 in
Microgreens Broadcast dense Tray sown Tray based 10 to 12 trays Not grown outdoors
Geraniums, in pots 10 to 12 in Bench spaced 0.85 to 1 32 pots Not applicable
Sq ft per plant is the product of in-row and row spacing, so it already includes the share of path and shoulder each plant occupies. Plants per bed assumes a 4 by 8 ft bed with access from both sides. For the cut-and-come-again and broadcast crops the figures are per single sowing rather than per season, because those crops are cut and resown repeatedly.

Vertical training changes the arithmetic completely

The most important number in the table is not a spacing, it is the note that tomatoes and cucumbers are string trained. Left to sprawl, an indeterminate tomato occupies 9 to 12 square feet of floor and yields from whatever part of the plant gets light. Trained vertically on twine to a single leader, the same plant occupies 4 to 6 square feet and fruits along its whole height. In a greenhouse where floor area is the expensive resource, this roughly doubles yield per square foot.

The method is simple and needs two items. Run heavy polypropylene twine from an overhead wire down to each plant, then attach the stem every 12 inches with trellis clips rather than tying, because a tie constricts as the stem thickens and a clip does not. Remove all side shoots weekly. On a house with an 8 ft ridge a single leader reaches the wire in roughly ten weeks, after which you either stop it or lower the whole plant on its string.

Field tip

Peppers split, so support them differently

Peppers do not train to a single leader well. They branch naturally and a heavy crop splits the main fork, which usually ends the plant. The correct support is a cage or a ring of stakes rather than a string, and clip-on stake arms turn a single stake into a cage at the point the plant needs it, which is when the first fruit sets rather than at planting.

How much bed do you actually need?

Work backwards from what you want to eat. The table below converts the spacing figures into a realistic annual yield for a 4 by 8 ft greenhouse bed, which is the standard module most hobby houses are built around, using conservative rather than competition figures.

Figure 2. Realistic annual yield from one 4 x 8 ft greenhouse bed · 11 rows
Figure 2. Realistic annual yield from one 4 x 8 ft greenhouse bed
CropPlants per bedYield per plantBed total per seasonSeasons per year
Tomatoes, indeterminate 7 12 to 20 lb 85 to 140 lb 1
Peppers 11 3 to 6 lb 33 to 66 lb 1
Cucumbers, vertical 9 15 to 25 fruit 135 to 225 fruit 1 to 2
Lettuce, head 35 0.5 to 0.8 lb 18 to 28 lb 3 to 4
Lettuce, cut and come again 160 3 cuts each 25 to 40 lb 4 to 6
Spinach 120 0.25 lb 30 lb 3 to 4
Kale 18 2 to 4 lb over the season 36 to 72 lb 1 to 2
Radishes 320 1 oz 20 lb 5 to 8
Carrots 240 2 to 3 oz 30 to 45 lb 2 to 3
Basil 30 0.5 to 1 lb over the season 15 to 30 lb 1 to 2
Strawberries 20 0.5 to 1 lb 10 to 20 lb 1
Yield figures are conservative and assume adequate light, water and nutrition. Seasons per year assumes a frost-protected house in a mid-latitude climate. The number of seasons is where a greenhouse earns its keep: the same bed producing four crops of lettuce out-yields one crop of anything.

Bench spacing is a different problem from bed spacing

Pots on a bench have a second constraint that plants in the ground do not: they must all be reachable and they must all be waterable. A bench deeper than about 30 inches with access from one side leaves the back row unwatered and unpicked, which is how the back row dies. Thirty inches is the practical maximum for one-sided access and 60 inches for two-sided.

Open mesh staging such as mesh greenhouse racks matters here for the same airflow reason as spacing does. Solid shelving blocks vertical air movement, so pots on a solid shelf sit in still air with a wet surface, which is the damping-off condition. A capillary mat on the bench solves the watering-reach problem by watering from below, so a deeper bench becomes workable.

Spacing and training equipment

Vertical training doubles the yield per square foot on fruiting crops, and airflow is what lets you use the spacing figures in the chart rather than something wider.

Size the bed and its soil with the bed and soil volume calculator, work back from a target harvest with the greenhouse size calculator, and read the in-house bed detail in raised beds inside a greenhouse. Crop by crop specifics are under by crop.

Related on this site

Common questions

6 answers

+ How far apart should greenhouse tomatoes be planted?

Sixteen to 20 inches apart in rows 30 to 36 inches apart, giving 4 to 6 square feet per plant, when the plants are string trained to a single leader. That is roughly twice the spacing packets suggest for outdoor growing, and the reason is airflow rather than light: still greenhouse air makes disease the limiting factor, so a dense canopy fails before it fruits fully.

+ How many plants fit in a 4 by 8 raised bed in a greenhouse?

It depends entirely on the crop. A 32 square foot bed holds 6 to 8 string-trained indeterminate tomatoes, 10 to 12 peppers, 32 to 38 head lettuce, 96 to 145 spinach, or 250 to 400 radishes. The useful way to plan is by square feet per plant rather than by plant count, because that figure already includes each plant share of the shoulder and path space.

+ Is greenhouse spacing different from outdoor spacing?

Yes, consistently wider, typically by 25 to 100 percent depending on crop. Outdoors, wind dries leaf surfaces within minutes of dew forming. Under cover, air is still unless you move it, and a saturated layer sitting on a leaf overnight is what botrytis and mildew need. Wider spacing plus a circulation fan produces more total food than packet spacing does, because nothing is lost to disease.

+ Can I plant closer if I have a circulation fan?

Somewhat, and this is exactly what commercial growers do. Continuous horizontal airflow across the canopy lets you use the tighter end of each range in the chart rather than the wider end. It does not let you use outdoor packet spacing, because a fan cannot fully substitute for the light penetration a wider canopy allows, but it is the difference between the top and bottom of each range.

+ How deep should a greenhouse bed be?

Twelve inches is workable for salad, roots and brassicas. Eighteen to 24 inches is much better for indeterminate tomatoes, peppers and cucumbers, because those crops root deeply and a shallow bed forces daily watering through the summer. Depth is the cheapest way to reduce watering frequency, and in a greenhouse where there is no rainfall at all, that matters more than it does outdoors.

+ How wide should a greenhouse bench be?

No more than about 30 inches if you can only reach it from one side, and up to about 60 inches with access from both. Beyond that the back row does not get watered or picked consistently, which is how the back row dies. A capillary mat that waters from below extends the practical depth, because reaching to water is what limits it rather than reaching to harvest.

Working out the figures for your own house and season? The Greenhouse Build & Growing Planner is the paid version of these pages: 8 printable worksheets you fill in with your own numbers, plus the full PDF, $29.