Flowers
Petunia Plant Spacing Calculator
Petunia × hybrida
Start with the source-backed 12-inch spacing default, then enter your bed length and width to calculate an approximate plant count, seeds or starts needed, and the spacing used. Defaults are editable so your variety and growing system can take priority.
Quick spacing answer
How far apart should you plant petunia?
Start with 12 inches between plants using a square grid layout. The source-backed range in this dataset is 12–24 inches.
At a glance
- Recommended spacing
- 12″
- Supported range 12–24″
- Planting pattern
- Square grid
- Time to first production
- 70–95 days from sowing
- Succession planting
- Not typical
- Start indoors
- 6 weeks before
- before transplanting
- Production pattern
- Standard
How many petunia plants do I need?
Enter your bed length and width below. The shared calculator is prefilled with Petunia's sourced spacing and shows the approximate plant count, spacing used, and seeds, starts, or planting material to prepare where appropriate.
Your plan
- Spacing used
- 12″
- Seeds to start (10% buffer)
- 221
- 72-cell trays needed
- 4
- 128-cell trays needed
- 2
Petunia spacing chart
These values come from the existing crop record. The density column is derived planning math and does not add a new horticultural recommendation.
| Context | Spacing | Geometric plants/sq ft |
|---|---|---|
| Dataset default | 12″ | 1.00 |
| Source-supported range | 12–24″ | Varies with selected spacing |
Plants per square foot is transparent square-grid planning math (144 ÷ spacing²), not an extension-service recommendation or a guarantee of field performance.
Petunia in raised beds
Enter the raised bed's actual length and width in the calculator. It applies the selected spacing and square grid model to estimate how many planting positions fit; it does not assume a crop-specific raised-bed recommendation that is absent from the source data.
Petunia per square foot
At 12″ spacing, square-grid geometry equals approximately 1.00 plants per square foot. This is a geometric planning estimate based on the displayed spacing—not an agronomic guarantee. The calculator may use a different documented model for square grid layouts.
Why petunia spacing changes
Variety, production system, support, and planting layout can change usable spacing. Plantometry keeps the sourced default editable and shows a range only when the crop record supports one.
How many petunia plants fit in my bed?
Use the calculator above with your bed dimensions. The result shows the approximate plant count, the spacing used, and seeds or planting material to prepare where appropriate.