Read the source range before choosing a number
The RHS range is a thinning range, not a single universal spacing. It spans 15–30 cm (about 6–12 inches) between retained parsley plants, and the source ties the choice to variety and harvest size. Pick your cultivar and the size you intend to harvest before you mark positions.
For a clearly labeled scenario, this guide uses 12 inches between retained plants. That is the upper end of the provided range, so it is a deliberate choice for that scenario, not a claim that every parsley variety should be spaced at 12 inches. If your chosen variety or harvest size points elsewhere in the range, use that value instead and keep the same counting method.
- Confirm the cultivar and intended harvest size before selecting a spacing value.
- Choose a center spacing within the provided 15–30 cm (6–12 inch) thinning range and label it as your scenario.
- Record the row spacing separately from the in-row spacing, using the provided 20–30 cm (8–12 inch) row range.
Source context: Royal Horticultural Society
Mark one measured row and count retained plants
The worked example is a single 96-inch row with 12-inch centers and a 6-inch margin at both ends. The first retained plant center falls at 6 inches and the last at 90 inches, giving 8 counted positions. The counted item is retained plants, meaning plants you intend to keep after thinning or at initial planting, not seeds sown and not seedlings that will later be removed.
This is a geometrical example, not crop advice for a particular cultivar. It shows how end margins and center spacing interact in one row. The same method applies in centimeters if you measure in centimeters, but keep the units consistent throughout the row.
- Measure the actual row length and note the unit.
- Set a margin at each end so plants are not crowded against the row boundary.
- Mark centers at your selected interval, starting after the first margin.
- Count only the retained plant positions, not every seed or seedling.
Source context: Royal Horticultural Society
Separate sowing, thinning and established plants
Sowing density, thinning spacing and the spacing of established plants are different stages. The RHS figure describes thinning parsley to a final in-row spacing; it does not prescribe seed-sowing density. Treat the marked positions as the places where retained plants should end up.
When you thin, remove seedlings until the remaining plants sit at your chosen centers. If you are setting out initial plants rather than thinning sown seedlings, use the same retained-plant positions. Keep a record of which stage each mark represents so the count is not confused with seeds sown.
- Label each mark as a retained plant position.
- Thin or set plants so the final retained plants align with those marks.
- Check that removed seedlings are not counted in the retained-plant total.
Source context: Royal Horticultural Society
Plan access, adjacent rows and mature habit separately
One measured row is not an entire garden layout. The RHS row range of 20–30 cm (about 8–12 inches) describes spacing between rows, but access paths, supports, adjacent crops and the mature habit of your chosen parsley still need their own decisions. Do not infer those distances from the row example.
Use the row calculator to count this exact length, center interval and both end margins in inches or centimeters. Then sketch the surrounding bed separately, deciding where you will walk, how adjacent rows relate, and whether the mature plants need room beyond the marked centers. Those choices belong to your layout, not to the single-row count.
- Count retained plants for one row using the row length, center interval and both end margins.
- Sketch access and adjacent rows separately from the counted row.
- Review the mature habit of your chosen cultivar before finalizing the bed layout.
Source context: Royal Horticultural Society
Check your measured example
One measured 96-inch row, with selected 12-inch centers and 6-inch margins at both ends. Count 8 retained plants.
Reference and growing system: RHS describes thinning parsley to 15–30 cm, approximately 6–12 inches, depending on variety, and rows 20–30 cm, approximately 8–12 inches, apart. Select harvest size and cultivar before counting.
| Quantity | Calculated result |
|---|---|
| Usable row length (in) | 96 |
| Selected center spacing (in) | 12 |
| Margin at each row end (in) | 6 |
| Positions in this row | 8 |
| First center from row start (in) | 6 |
| Last center from row start (in) | 90 |
| What is being counted | retained plants |
The worked example is one 96-inch row with 12-inch centers and 6-inch margins at both ends. The first center is at 6 inches and the last at 90 inches, producing 8 retained plant positions. This is a geometrical illustration of the counting method, not crop advice; the 12-inch value is a labeled scenario within the RHS thinning range, and the example does not set access, support or adjacent-row distances.
Count this row in the spacing calculator ↗Example inputs explain the method. Review the source context, chosen cultivar and actual site before planting or ordering.
Your before-you-plant checklist
- Cultivar and intended harvest size recorded before choosing a spacing value.
- Selected center spacing labeled as a scenario within the provided 15–30 cm (6–12 inch) thinning range.
- Row length, center interval and both end margins entered in consistent units.
- Counted item confirmed as retained plants, not seeds sown or seedlings to be removed.
- Access, adjacent rows and mature habit sketched separately from the single counted row.
Questions that come up while planning
What spacing does the RHS give for thinning parsley?
The RHS describes thinning parsley to 15–30 cm (about 6–12 inches) depending on variety, with rows 20–30 cm (about 8–12 inches) apart. Choose within that range based on your cultivar and harvest size.
Does the 96-inch example apply to every parsley variety?
No. It is a labeled geometrical scenario using 12-inch centers and 6-inch end margins. It shows the counting method, not a recommendation for a specific cultivar or harvest size.
Does one counted row define my whole raised bed?
No. The count covers retained plants in one measured row. Access, supports, adjacent rows and mature habit must be planned separately, and the source notes do not set those distances.
Sources & method
Horticultural guidance is linked to its original source and regional context. Geometry and unit conversions are calculated separately. Read how we prepare and check a page.
- How to grow ParsleyRoyal Horticultural Society