Measure the planting area
Use the internal bed length and width in metres.
Plant Spacing Calculator
Enter bed size and spacing in centimetres to estimate a simple planting grid — then refine using each plant’s mature spread.
Calculator
Tap a screen and type with the keypad (or your keyboard), choose an option, then press =. The answer shows on the calculator screen, with full details underneath.
Garden Plant Finder
PLANT SPACING · GPF
How to measure
Follow these steps for accurate inputs and better results.
Check mature spread
Read the plant label — spacing is about adult size, not the pot size today.
Convert to a grid
The calculator divides the bed into equal centres.
Adjust for design
Drift plantings and staggered rows often look more natural than a rigid grid.
Why this matters
Correct spacing reduces disease, competition and the need to move plants later.
Buying the right number of plants saves money and avoids sparse-looking beds.
A grid estimate is a starting point — combine it with Plant Finder mature sizes for best results.
Common mistakes
Spacing for today’s size
Seedlings look lonely — they won’t stay that way.
Overcrowding for instant impact
Looks full year one, then weak growth and mildew follow.
Ignoring access
Leave room to weed and harvest without trampling.
One spacing for mixed borders
Group by mature size; tall and low plants need different gaps.
Forgetting edges
Keep vigorous spreaders back from paths and lawns.
Tips from gardening experts
Stagger rows
Offset planting uses space efficiently and looks softer.
Plant in odd numbers
Drifts of 3, 5 or 7 read more naturally.
Use temporary fillers
Annuals bridge gaps while perennials bulk up.
Cross-check Plant Finder
Filter by height and spread before you buy in bulk.
Frequently asked questions
How do I calculate plants per square metre?
Roughly 10,000 ÷ (spacing_cm × spacing_cm). Example: 40 cm spacing ≈ 6 plants/m².
What spacing for lavender?
Often 30–45 cm depending on variety mature width — check the label.
Should I space closer in poor soil?
Usually no — stressed plants need air and resources. Improve soil instead.
How many plants in a 3×1 m bed at 40 cm?
About 7 × 2 = 14 plants on a simple grid (length/0.4 × width/0.4).
Is triangular spacing better?
Staggered (triangular) spacing can fit plants more efficiently and look less regimented.
Do vegetables use different spacing?
Yes — follow crop-specific charts for rows vs stations. This tool is a general grid helper.
What if my bed is an odd shape?
Split into rectangles, calculate each, then add.
Can I transplant if I overplant?
Many perennials move in dormant seasons, but it’s extra work — space generously first.
How does spacing affect disease?
Tighter spacing reduces airflow and can raise mildew and blackspot risk.
Where can I check mature plant size?
Use our Plant Finder filters and individual plant pages for height and spread.
Sources and further reading
Want more detail? These pages from the Royal Horticultural Society (RHS), the UK’s gardening charity, explain the topic in depth.
Related guides
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Downloads
Planting grid checklist
Measure, mark centres, plant, water, mulch.
Spacing cheat sheet PDF
Placeholder common spacings.
Get seasonal gardening advice
See what to sow, plant and prune each month in the Garden Plant Finder seasonal calendar.
Ready to choose plants?
Use Plant Finder filters for soil, sun, wildlife and flowering month — then plan quantities with these calculators.