Horticultural calculators & planning tools
Four working tools built from the numbers we use on the nursery floor: pot volumes, component porosity, window light in British homes, trade pricing and commercial display ratios.
Substrate volume & repotting calculator
Litres of each mix, the cheapest bag combination, clear pot sizes, moss-pole moss and a component recipe adjusted for your room.
Indoor light (PPFD) & plant finder
Window direction and distance from glass become an estimated PPFD and DLI, matched to genera that will actually grow there.
Trade stockist margin & shelf planner
Wholesale cost ex-VAT, carriage-paid qualification, retail revenue and margin per line for independent plant shops.
Commercial plant scheme estimator
Floor area, desks and light level become a display schedule and monthly maintenance fee, with rental and purchase compared.
Questions we are asked most
Still unsure? Email care@growtropic.co.uk with a photo of the plant and its roots — the nursery team replies Monday to Thursday.
Are the calculators accurate enough to order from?
The repotting calculator uses the real fill volumes of our clear slotted pots plus a 15% settling allowance, which is what we use when packing bundles in the nursery. Most customers end up within half a litre. If you are between two bag combinations, the calculator already picks the cheaper one that covers the volume.
Can I save or share a result?
Yes. Every change you make is written into the page address, so copying the link, bookmarking it or pasting it into a forum post reproduces the exact calculation. Each tool also prints a clean one-page sheet, or you can save that sheet as a PDF from the print dialogue.
What happens when I press the order button?
You are taken to our order and enquiry page with the full result already written into the form: mixes, litres, bag counts, pot sizes and the estimated price. Nothing is charged at that point. The nursery confirms stock and delivery, then sends a payment link.
Do the light estimates replace a light meter?
No. They are typical values for British homes, worked out from window orientation, distance and season. A cheap PAR meter or a phone app calibrated for PPFD will give you the real number for your room. Use the estimate to shortlist plants and to decide whether a grow light is needed.