Garden Bed Planner

Limited growing space makes every dimension do more than one job. Bed width determines how many planting lanes fit, length limits plants per lane, and soil depth affects root space and the amount of material needed. In containers, surface area and volume both matter because foliage may fit above the rim while roots still compete below it.

Spacing is a starting point for mature plants, not a promise that every spot will thrive. Cultivar size, trellising, airflow, sun, soil fertility, disease pressure, and local weather can all justify wider spacing. Seed packets and local extension guidance should take priority over a generic crop preset when they disagree.

• Capacity is the whole number of plants that fit after spacing and reserved edges are applied.
• Seed need is larger than plant capacity when germination is below 100% or an extra seed buffer is added.
• Soil volume estimates fill material from physical dimensions; settling, compaction, and incomplete filling can change the purchase amount.
• Harvest timing adds a preset maturity period to the planting date. Temperature and cultivar performance can move the real date.

Raised beds and containers also fail in different ways. A crowded bed can lose airflow and access even when the arithmetic says another row fits. A shallow or low-volume container can dry quickly and restrict roots. Productive planning therefore combines geometry with a final check of crop habit, drainage, watering frequency, and the conditions at the site.

How to Use This Tool:

Choose the growing setup first because bed rows and container capacity use different rules.

1. Select Raised bed or Containers / patio, then choose the crop preset closest to the cultivar you intend to grow. Confirm its spacing and root-space assumptions against the seed packet.
2. For a raised bed, enter the inside length, width, soil depth, and row layout. Add an edge buffer only for space that must remain unplanted; two edge buffers must leave a positive width.
3. For containers, enter the number of pots plus each pot's inside diameter and depth. Capacity is limited by both top area and mix volume, so changing either dimension can change plants per container.
4. Enter the planting date and optional seed buffer. Enable a pollinator row only when one full calculated row should be reserved and excluded from crop capacity.
5. Review plant capacity, seed and packet counts, soil or mix volume, and the watering-margin signal. Use the placement rows as a draft, then widen spacing where access, airflow, or cultivar habit requires it.

Interpreting Results:

Planned plants is a geometric capacity, not a recommendation to fill every position. The seed count already accounts for the preset germination percentage and optional buffer, while packet count rounds up to whole packets.

• In bed mode, compare productive rows and plants per row with the placement plan. A pollinator row has zero crop plants by design.
• In container mode, a Medium or High watering-margin signal means depth or mix volume per plant is below the preset reference. Reduce plants per pot or choose a larger container before relying on the estimate.
• Soil fill and potting-mix values are geometric volumes. Buy with a practical allowance for settling only after checking how the material is sold.
• Estimated yield and first harvest date are planning clues. Weather, cultivar, pests, fertility, and harvest style can move both substantially.

Technical Details:

The calculation uses crop-specific lookup values for in-row spacing, row spacing, germination percentage, seeds per packet, maturity days, yield per plant, minimum root depth, and minimum container volume. These presets are planning assumptions, not official cultivar specifications.

Formula Core

For raised beds, width determines row count and length determines plants per row. Every count is rounded down because a partial row position cannot hold another whole plant.

B and L are bed width and length in meters, E is the edge buffer on each side, and spacing values are centimeters. Double layout multiplies the base row count by two; single and staggered layouts use the base row count. A pollinator strip subtracts one row from the effective count. Soil fill is length × width × depth in meters, reported as m³.

A round container is limited by the smaller of surface capacity and volume capacity.

Diameter d and depth z are centimeters, so dividing cubic centimeters by 1,000 gives liters. Surface need is the larger of 100 cm² or 90% of squared plant spacing. Minimum volume is the crop preset's gallons converted at 3.785411784 L/gal. If depth is below 75% of the preset minimum, capacity is forced to one plant per container.

Seed purchasing rounds upward at each whole-item boundary.

P is planned plants, b is extra seed percentage, g is germination percentage, q is seeds per packet, and K is whole packets.

Lookup and warning rules

The first-harvest date is the entered calendar date plus the preset maturity days. Estimated yield multiplies planned plants by a preset pounds-per-plant assumption and converts pounds to kilograms at 0.45359237 kg/lb.

Limitations and Accuracy Notes:

Geometry cannot inspect the site or cultivar. The plan does not model frost dates, soil temperature, succession planting, companion compatibility, crop rotation, sunlight, irrigation, drainage, soil test results, pests, or disease.

• Measure inside dimensions and usable soil depth rather than nominal lumber or pot size.
• Container volume assumes a vertical cylinder. Tapered pots and rounded bottoms hold less mix.
• Crop spacing, germination, maturity, and yield values are approximate presets. Replace them with packet and local guidance when planning purchases.
• Do not use the yield estimate as a harvest guarantee or the date as a frost-safe planting recommendation.

Worked Examples:

References:

• Growing Vegetables in Raised Beds, University of Maryland Extension.
• Growing Vegetables in Containers and Salad Tables, University of Maryland Extension.
• Crop and Field Planning Tools for Vegetable Farmers, University of Minnesota Extension.