---
title: "Square Foot Gardening Planner: Grid-Based Plant Density from Bed Size and Spacing Rules"
canonical: "https://theyieldgrid.com/square-foot-gardening-planner/"
model_id: "tyg-855"
model_version: "1.0.0"
last_reviewed: "2026-08-25T01:39:44"
reviewed_by: "Umer Hayiat"
---

# Square Foot Gardening Planner: Grid-Based Plant Density from Bed Size and Spacing Rules

> Canonical calculator: [https://theyieldgrid.com/square-foot-gardening-planner/](https://theyieldgrid.com/square-foot-gardening-planner/)

## What this calculator does

Home - Free Gardening Calculators & Tools - Square Foot Gardening Planner: Grid-Based Plant Density from Bed Size and Spacing Rules Planting more vegetables into a raised bed does not automatically mean a bigger harvest. Spacing too tight invites disease pressure, root competition, and premature bolting. Spacing too loose wastes productive soil surface that took weeks to prepare. The square foot gardening method resolves this tension by converting bed dimensions into a fixed grid and assigning each plant a precise number of cells based on its mature root and canopy width.

## Inputs

| Input | ID | Type | Unit | Range or choices | Required |
|---|---|---|---|---|---|
| Bed Width (ft) | `sfgplanner_width` | number | ft | 1 to 20 | No |
| Bed Length (ft) | `sfgplanner_length` | number | ft | 1 to 20 | No |
| Vegetable / Plant | `sfgplanner_veggie` | select |  | — Select a plant — = ``; Tomato (1 per sq ft) = `tomato_1`; Pepper (1 per sq ft) = `pepper_1`; Broccoli (1 per sq ft) = `broccoli_1`; Cabbage (1 per sq ft) = `cabbage_1`; Eggplant (1 per sq ft) = `eggplant_1`; Cucumber (2 per sq ft) = `cucumber_2`; Swiss Chard (4 per sq ft) = `swiss_chard_4`; Lettuce (4 per sq ft) = `lettuce_4`; Spinach (9 per sq ft) = `spinach_9`; Onion / Green Onion (16 per sq ft) = `onion_16`; Radish (16 per sq ft) = `radish_16`; Carrot (16 per sq ft) = `carrot_16`; Beet (9 per sq ft) = `beet_9`; Pea (8 per sq ft) = `pea_8`; Bush Bean (9 per sq ft) = `bean_9`; Basil (4 per sq ft) = `basil_4`; Parsley (4 per sq ft) = `parsley_4`; Kale (1 per sq ft) = `kale_1` | No |

## Outputs

| Output ID | Default state |
|---|---|
| `sfgplanner_width_err` |  |
| `sfgplanner_length_err` |  |
| `sfgplanner_veggie_err` |  |
| `` | 0 Total Plants 0 sq ft bed 0 plants / sq ft Your Square Foot Garden Grid Spacing & Density Checks Common SFG Spacing Reference Plant Per Sq Ft Spacing In your bed Density How This Calculator Works & Assumptions Formula Steps: Grid Area (sq ft) = Bed Width (ft) × Bed Length (ft) Total Plants = Grid Area × Plants Per Square Foot Area : Multiply width × length to get total square feet (e.g. 4 ft × 4 ft = 16 sq ft). Density : Each plant type has a fixed SFG spacing value (1, 2, 4, 9, or 16 plants pe |
| `sfgplanner_resultsPanel` | 0 Total Plants 0 sq ft bed 0 plants / sq ft Your Square Foot Garden Grid Spacing & Density Checks Common SFG Spacing Reference Plant Per Sq Ft Spacing In your bed Density How This Calculator Works & Assumptions Formula Steps: Grid Area (sq ft) = Bed Width (ft) × Bed Length (ft) Total Plants = Grid Area × Plants Per Square Foot Area : Multiply width × length to get total square feet (e.g. 4 ft × 4 ft = 16 sq ft). Density : Each plant type has a fixed SFG spacing value (1, 2, 4, 9, or 16 plants pe |
| `sfgplanner_out_primary` | 0 |
| `sfgplanner_out_sqft` | 0 |
| `sfgplanner_out_density` | 0 |
| `sfgplanner_warningsBox` | Spacing & Density Checks |

## Formula and method

How bed dimensions and SFG density values combine to generate precise plant counts and grid layouts. Show the calculation steps Step 1: Compute bed area Grid Area (sq ft) = Bed Width (ft) x Bed Length (ft) Example: 4 ft x 8 ft = 32 sq ft No rounding is needed at this step since both inputs are whole numbers. Step 2: Look up plants-per-square-foot (ppsf) Each plant in the SFG system has a fixed ppsf value derived from its mature canopy and root spread. The lookup values used in this planner are: 1, 2, 4, 8, 9, or 16. There is no interpolation between values. Step 3: Compute total plants Total Plants = Grid Area (sq ft) x ppsf Example: 32 sq ft x 4 ppsf (Lettuce) = 128 plants Results are always whole numbers since both inputs are integers and ppsf is always a whole number. Rounding rules: No rounding is required. All intermediate values are exact integers. Unit conversions: None. The tool works exclusively in feet and counts. Do not convert feet to inches before entering values. Assumptions and Limits Bed dimensions are entered in whole feet only. Beds measured in fractional feet (e.g., 3.5 ft x 7 ft) should be rounded down to the nearest foot to avoid oversowing the physical space. The planner assumes the entire bed is filled with one plant type. Mixed-crop beds require a separate calculation for each zone, treating each zone as its own independent rectangular area. ppsf values follow Mel Bartholomew’s original SFG system. Newer cultivar introductions with different mature sizes (e.g., miniature pumpkins vs. full-size) are not modeled separately. Soil depth, drainage, and soil composition are not factored in. Root-depth-sensitive crops like carrots require a minimum of 12 inches of loose soil regardless of the plant count produced by this formula. Bed maximum width of 20 ft is a software limit. Physically, beds wider than 4 ft compromise reachability and are flagged as a warning in the output. The planner does not account for germination failure rates. For direct-sown crops (carrot, radish, spinach), actual seed quantity should exceed the calculated plant count to compensate for expected germination gaps. This tool treats the bed as a flat, unobstructed rectangle. Beds with embedded irrigation risers, support posts, or permanent corner structures will have a lower effective planting area than the computed grid area. The core formula is: Grid Area (sq ft) = Bed Width x Bed Length. Total Plants = Grid Area x Plants Per Square Foot. The plants-per-square-foot value is a fixed lookup for each crop type, derived from its mature canopy and root spread. The SFG system uses values of 1, 2, 4, 8, 9, or 16 plants per square foot depending on the crop.

## Verified worked examples

### Example 1: Standard 4×4 Bed Planted with Lettuce

Bed Width: 4 ft Bed Length: 4 ft Vegetable: Lettuce (4 plants per sq ft, 6-inch spacing) Result: 4 x 4 = 16 sq ft. 16 sq ft x 4 plants/sq ft = 64 lettuce plants. A 16 sq ft bed at this density produces a grid of 64 individual leaf lettuce or butterhead plants. Harvesting outer leaves from each plant extends yield across the entire season without uprooting the grid prematurely.

### Example 2: 4×8 Bed Planted with Tomatoes

Bed Width: 4 ft Bed Length: 8 ft Vegetable: Tomato (1 plant per sq ft, 12-inch spacing) Result: 4 x 8 = 32 sq ft. 32 sq ft x 1 plant/sq ft = 32 tomato plants. Thirty-two indeterminate tomato plants in a 32 sq ft bed is the SFG-compliant maximum. In practice, most gardeners plant 16 tomatoes (half the bed) and reserve the remaining 16 sq ft for a high-density companion like basil at 4 ppsf, computing each section separately.

### Example 3: 3×6 Bed Planted with Carrots

Bed Width: 3 ft Bed Length: 6 ft Vegetable: Carrot (16 plants per sq ft, 3-inch spacing) Result: 3 x 6 = 18 sq ft. 18 sq ft x 16 plants/sq ft = 288 carrots. At 16 ppsf, carrots are among the densest SFG crops. 288 seeds sown in an 18 sq ft bed requires thinning to avoid forked roots. Thin to one plant per cell position after germination rather than waiting until crowding is visible at the surface.

## Assumptions

Bed Width: 4 ft Bed Length: 4 ft Vegetable: Lettuce (4 plants per sq ft, 6-inch spacing) Result: 4 x 4 = 16 sq ft. 16 sq ft x 4 plants/sq ft = 64 lettuce plants. A 16 sq ft bed at this density produces a grid of 64 individual leaf lettuce or butterhead plants. Harvesting outer leaves from each plant extends yield across the entire season without uprooting the grid prematurely. How bed dimensions and SFG density values combine to generate precise plant counts and grid layouts. Show the calculation steps Step 1: Compute bed area Grid Area (sq ft) = Bed Width (ft) x Bed Length (ft) Example: 4 ft x 8 ft = 32 sq ft No rounding is needed at this step since both inputs are whole numbers. Step 2: Look up plants-per-square-foot (ppsf) Each plant in the SFG system has a fixed ppsf value derived from its mature canopy and root spread. The lookup values used in this planner are: 1, 2, 4, 8, 9, or 16. There is no interpolation between values. Step 3: Compute total plants Total Plants = Grid Area (sq ft) x ppsf Example: 32 sq ft x 4 ppsf (Lettuce) = 128 plants Results are always whole numbers since both inputs are integers and ppsf is always a whole number. Rounding rules: No rounding is required. All intermediate values are exact integers. Unit conversions: None. The tool works exclusively in feet and counts. Do not convert feet to inches before entering values. Assumptions and Limits Bed dimensions are entered in whole feet only. Beds measured in fractional feet (e.g., 3.5 ft x 7 ft) should be rounded down to the nearest foot to avoid oversowing the physical space. The planner assumes the entire bed is filled with one plant type. Mixed-crop beds require a separate calculation for each zone, treating each zone as its own independent rectangular area. ppsf values follow Mel Bartholomew’s original SFG system. Newer cultivar introductions with different mature sizes (e.g., miniature pumpkins vs. full-size) are not modeled separately. Soil depth, drainage, and soil composition are not factored in. Root-depth-sensitive crops like carrots require a minimum of 12 inches of loose soil regardless of the plant count produced by this formula. Bed maximum width of 20 ft is a software limit. Physically, beds wider than 4 ft compromise reachability and are flagged as a warning in the output. The planner does not account for germination failure rates. For direct-sown crops (carrot, radish, spinach), actual seed quantity should exceed the calculated plant count to compensate for expected germination gaps. This tool treats the bed as a flat, unobstructed rectangle. Beds with embedded irrigation risers, support posts, or permanent corner structures will have a lower effective planting area than the computed grid area. Bed dimensions are entered in whole feet only. Beds measured in fractional feet (e.g., 3.5 ft x 7 ft) should be rounded down to the nearest foot to avoid oversowing the physical space. The planner assumes the entire bed is filled with one plant type. Mixed-crop beds require a separate calculation for each zone, treating each zone as its own independent rectangular area. ppsf values follow Mel Bartholomew’s original SFG system. Newer cultivar introductions with different mature sizes (e.g., miniature pumpkins vs. full-size) are not modeled separately. Soil depth, drainage, and soil composition are not factored in. Root-depth-sensitive crops like carrots require a minimum of 12 inches of loose soil regardless of the plant count produced by this formula. Bed maximum width of 20 ft is a software limit. Physically, beds wider than 4 ft compromise reachability and are flagged as a warning in the output. The planner does not account for germination failure rates. For direct-sown crops (carrot, radish, spinach), actual seed quantity should exceed the calculated plant count to compensate for expected germination gaps. This tool treats the bed as a flat, unobstructed rectangle. Beds with embedded irrigation risers, support posts, or permanent corner structures will have a lower effective planting area than the computed grid area. Critical Warnings Bed width above 4 ft: The SFG method is built around a 4-foot maximum width because an average adult can comfortably reach 2 feet from each side of the bed. Beds wider than 4 ft require stepping onto the growing surface to tend interior squares, which compacts the soil and defeats the core benefit of the raised-bed system. The planner flags this automatically. Dense crops require thinning, not just sowing: Crops at 9 or 16 ppsf (carrot, radish, onion, spinach) are typically sown at a higher rate than the ppsf target and then thinned after germination. The planner calculates the final stand count, not the sowing count. Treating the output as a seed count for high-density crops will result in undercrowded beds. Vertical crops change the effective footprint: Vining cucumbers, peas, and indeterminate tomatoes have a canopy that expands far beyond their 1 sq ft ground position when not trained vertically. The 1 ppsf and 2 ppsf values assume vertical growing with appropriate support structures in place. One calculation covers one bed, one crop: The formula does not support irregular bed shapes or mixed planting zones in a single entry. Running separate calculations for each sub-zone is required for accurate totals. The succession planting chart provides a framework for sequencing multiple crops across the same bed over a growing season. Minimum Standards Bed soil should be a minimum of 6 inches deep for shallow-rooted crops (lettuce, spinach, radish) and at least 12 inches for root crops (carrot, beet, onion). Plant count accuracy is meaningless if root depth is insufficient for the selected crop. Grid cells are defined as 1 ft x 1 ft squares. Any bed dimension entered in non-foot units will produce an incorrect area and incorrect plant count. Always convert measurements before entry. Competitor Trap: Many square foot gardening planning tools present spacing in linear inches along a row, which is a row-crop convention, not an SFG convention. The SFG method distributes plants uniformly across a square cell, not along a single axis. A “6-inch spacing” in a row system places two plants per linear foot in one direction only. In an SFG grid, 6-inch spacing places four plants per square foot because the spacing applies in both dimensions simultaneously (6 in x 6 in = 0.25 sq ft per plant = 4 plants per sq ft). Tools that display only “spacing in inches” without converting to a per-square-foot count routinely cause gardeners to underplant dense crops like lettuce and spinach by a factor of two or more. Bed soil should be a minimum of 6 inches deep for shallow-rooted crops (lettuce, spinach, radish) and at least 12 inches for root crops (carrot, beet, onion). Plant count accuracy is meaningless if root depth is insufficient for the selected crop. Grid cells are defined as 1 ft x 1 ft squares. Any bed dimension entered in non-foot units will produce an incorrect area and incorrect plant count. Always convert measurements before entry. Competitor Trap: Many square foot gardening planning tools present spacing in linear inches along a row, which is a row-crop convention, not an SFG convention. The SFG method distributes plants uniformly across a square cell, not along a single axis. A “6-inch spacing” in a row system places two plants per linear foot in one direction only. In an SFG grid, 6-inch spacing places four plants per square foot because the spacing applies in both dimensions simultaneously (6 in x 6 in = 0.25 sq ft per plant = 4 plants per sq ft). Tools that display only “spacing in inches” without converting to a per-square-foot count routinely cause gardeners to underplant dense crops like lettuce and spinach by a factor of two or more. The dropdown entries reflect standard mature sizes. A cherry tomato plant occupies 1 sq ft in the SFG system, the same as a full-size beefsteak, because both are managed vertically. Selecting “Lettuce (4 per sq ft)” for a large crisphead variety like Iceberg that needs 12-inch spacing will double the calculated plant count. Fix: verify the specific variety’s mature head diameter before accepting the ppsf value from the dropdown.

## Limitations and safety

Bed dimensions are entered in whole feet only. Beds measured in fractional feet (e.g., 3.5 ft x 7 ft) should be rounded down to the nearest foot to avoid oversowing the physical space. The planner assumes the entire bed is filled with one plant type. Mixed-crop beds require a separate calculation for each zone, treating each zone as its own independent rectangular area. ppsf values follow Mel Bartholomew’s original SFG system. Newer cultivar introductions with different mature sizes (e.g., miniature pumpkins vs. full-size) are not modeled separately. Soil depth, drainage, and soil composition are not factored in. Root-depth-sensitive crops like carrots require a minimum of 12 inches of loose soil regardless of the plant count produced by this formula. Bed maximum width of 20 ft is a software limit. Physically, beds wider than 4 ft compromise reachability and are flagged as a warning in the output. The planner does not account for germination failure rates. For direct-sown crops (carrot, radish, spinach), actual seed quantity should exceed the calculated plant count to compensate for expected germination gaps. This tool treats the bed as a flat, unobstructed rectangle. Beds with embedded irrigation risers, support posts, or permanent corner structures will have a lower effective planting area than the computed grid area. Critical Warnings Bed width above 4 ft: The SFG method is built around a 4-foot maximum width because an average adult can comfortably reach 2 feet from each side of the bed. Beds wider than 4 ft require stepping onto the growing surface to tend interior squares, which compacts the soil and defeats the core benefit of the raised-bed system. The planner flags this automatically. Dense crops require thinning, not just sowing: Crops at 9 or 16 ppsf (carrot, radish, onion, spinach) are typically sown at a higher rate than the ppsf target and then thinned after germination. The planner calculates the final stand count, not the sowing count. Treating the output as a seed count for high-density crops will result in undercrowded beds. Vertical crops change the effective footprint: Vining cucumbers, peas, and indeterminate tomatoes have a canopy that expands far beyond their 1 sq ft ground position when not trained vertically. The 1 ppsf and 2 ppsf values assume vertical growing with appropriate support structures in place. One calculation covers one bed, one crop: The formula does not support irregular bed shapes or mixed planting zones in a single entry. Running separate calculations for each sub-zone is required for accurate totals. The succession planting chart provides a framework for sequencing multiple crops across the same bed over a growing season. Minimum Standards Bed soil should be a minimum of 6 inches deep for shallow-rooted crops (lettuce, spinach, radish) and at least 12 inches for root crops (carrot, beet, onion). Plant count accuracy is meaningless if root depth is insufficient for the selected crop. Grid cells are defined as 1 ft x 1 ft squares. Any bed dimension entered in non-foot units will produce an incorrect area and incorrect plant count. Always convert measurements before entry. Competitor Trap: Many square foot gardening planning tools present spacing in linear inches along a row, which is a row-crop convention, not an SFG convention. The SFG method distributes plants uniformly across a square cell, not along a single axis. A “6-inch spacing” in a row system places two plants per linear foot in one direction only. In an SFG grid, 6-inch spacing places four plants per square foot because the spacing applies in both dimensions simultaneously (6 in x 6 in = 0.25 sq ft per plant = 4 plants per sq ft). Tools that display only “spacing in inches” without converting to a per-square-foot count routinely cause gardeners to underplant dense crops like lettuce and spinach by a factor of two or more.

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## Provenance

- Model ID: `tyg-855`
- Model version: `1.0.0`
- Reviewed by: Umer Hayiat
- Page modified: 2026-08-25T01:39:44
- Runtime SHA-256: `865c817690bf3ae1eec6efaeac4c55a0fca737ab7565d0ce84f9082edfa31c87`

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