Clarify the required growing space and the empty-bag manufacturing dimensions before comparing quotations.
A nursery bag can match the dimensions on a purchase order and still be too small when filled.
The misunderstanding often begins before production. A grower describes the size needed after filling, while a supplier interprets those measurements as the dimensions of the empty bag laid flat.
Both descriptions are useful, but they are not interchangeable. Before preparing a quotation or approving a sample, establish one essential detail:
Are the measurements taken before or after filling?
Consider a hypothetical enquiry:
“We need a nursery bag approximately 20 cm in diameter and 30 cm high after filling.”
This describes the intended result in use. It does not yet define the dimensions needed to manufacture the empty bag.
If those numbers are copied directly into a 20 × 30 cm lay-flat specification, the quotation may appear to match the enquiry while describing a different product.
Providing the required filled size is a practical starting point. The next step is to translate that requirement into a bag design with clearly defined dimensions, construction and tolerances.
For plain tubing without gussets, the lay-flat width represents half the circumference of the opening—not its diameter.
Assuming a circular opening and no material stretch:
| Measurement provided | Illustrative conversion |
|---|---|
| 20 cm lay-flat width | 40 cm circumference, giving an opening diameter of approximately 12.7 cm |
| 20 cm circular opening diameter | Approximately 31.4 cm lay-flat width before allowances |
These calculations explain the difference between width and diameter. They are not a ready-to-order nursery bag specification and do not establish usable height or capacity.
For gusseted bags, the gussets add material around the opening. Their dimensions and the supplier’s measurement convention must therefore be included. The same calculation cannot be applied to the folded face width alone.
A clear specification should include two labelled views.
The intended filled bag should identify:
The proposed empty bag should identify:
Overall empty-bag length also needs a separate check. Material used to form the bottom, together with the filling shape and any folded rim, can affect the height available in use.
Measuring an empty bag checks its manufacturing dimensions. Filling a sample helps determine whether the proposed design provides the space the grower needs.
Use the intended growing medium and an agreed filling method. Check the resulting footprint or diameter, fill height, headspace and fit within the planned growing arrangement.
Keep the filling conditions consistent when comparing samples. Differences in medium compaction or fill level can make otherwise similar bags appear to provide different capacities.
The drawing defines what will be manufactured. The filled sample verifies whether that design meets the intended requirement.
Before comparing prices, ask suppliers to work from the same target filled dimensions and agreed sample conditions.
Also align the material, thickness and tolerances, bag construction, hole layout, order quantity and delivery scope.
A lower price for a smaller usable bag is not a like-for-like saving. Equally, a higher price does not establish that a supplier has interpreted the requirement correctly.
Look for a clear explanation of the proposed dimensions, a drawing that resolves ambiguity and a sample that can be evaluated against the original brief.
A nursery bag enquiry can begin with a photograph, an existing sample or the dimensions required after filling.
For your next project, share your crop, growing medium, target filled size, expected use period and any drainage or construction requirements with INTERPAC. Include both empty and filled measurements when available, and label them clearly.
A well-defined nursery bag starts with understanding the growing space it needs to provide.
