Cut flowers
Cosmos Plant Spacing Calculator
Cosmos bipinnatus / C. sulphureus
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 cosmos?
Start with 12 inches between plants using a intensive bed layout. The source-backed range in this dataset is 9–12 inches.
At a glance
- Recommended spacing
- 12″
- Supported range 9–12″
- Planting pattern
- Intensive bed
- Time to first production
- 75–110 days from sowing
- Succession planting
- Recommended
- Every 28 days
- Start indoors
- 4 weeks before
- before last frost
- Production pattern
- Cut-and-come-again
- Pinch
How many cosmos plants do I need?
Enter your bed length and width below. The shared calculator is prefilled with Cosmos'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
Cosmos 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 | 9–12″ | 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.
Cosmos in raised beds
Enter the raised bed's actual length and width in the calculator. It applies the selected spacing and intensive bed 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.
Cosmos 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 intensive bed layouts.
Why cosmos 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 cosmos 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.
More Cosmos planning
Planning notes
- Horizontal netting
- Landscape fabric
- Pinching
Cut-and-come-again. A planting keeps producing new stems over a relatively long harvest period when it is picked regularly, so successive plantings are usually spaced farther apart.
- This crop can be direct sown.
- Pinching is commonly used in this production system.
- Support netting is commonly used.
- Landscape fabric is commonly used for spacing and weed control.