Vegetable Gardening Online Planner
Plan any plot or allotment: how many plants fit, when to sow each crop, and when your first harvest lands.
Calculator Inputs
Crops To Grow
Each crop gets an equal share of your planting area; spacing figures are in Method and limits below.
Crop Breakdown
| Crop | Spacing | Plants | Sow | First Harvest |
|---|---|---|---|---|
| Select at least one crop above. | ||||
Scenario Analysis
| Scenario | Total Plants | Change |
|---|---|---|
| Current plan | - | - |
Sowing Timeline
February to MarchStart tomatoes and lettuce under cover, chit potatoes, and make the first outdoor sowings of carrots, lettuce and peas once the soil is workable.
Late March to AprilPlant onion sets and maincrop potatoes. The last frost falls around 8 April in the south of England and around 20 May in the Scottish Highlands.
MayPlant out courgettes, runner beans and tomatoes once frost risk has passed, then sow beetroot, spinach and your first succession batch of lettuce.
June and JulyFirst harvests arrive: radish at 4 weeks, lettuce at 8, peas at 11. Keep sowing quick crops every 3 weeks so the bed never sits empty.
August and SeptemberMaincrop potatoes, onions and kale fill the gap between summer and autumn, and a September sowing of lettuce gives cuts into October.
OctoberThe plot clears. Plan next season's rotation, clear finished crops, and order seed before the best varieties sell out.
How The Vegetable Gardening Planner Works
Three inputs decide everything. Plot length times width gives the area; the path allowance takes its cut (20% of an 8 m² plot leaves 6.4 m²); and the remaining planting area is split evenly across the crops you tick. Each crop's share is then divided by its per-plant footprint — in-row spacing times row spacing — and floored to a whole plant, because half a courgette plant is no use to anybody.
The whole chain in one pass: 6.4 m² divided by 5 crops is 1.28 m² per crop, and 1.28 m² divided by 0.075 m² (25 cm by 30 cm lettuce) gives 17 plants. The same 1.28 m² divided by 0.285 m² (38 cm by 75 cm potatoes) gives 4. One share, two very different answers, and the gap between them is spacing rather than luck.
What The Plant Count Actually Means
Spacing, not ambition, sets the number. Carrots need 0.018 m² per plant and courgettes need 0.81 m² — 45 times more ground for one courgette than for one carrot. Fill 6.4 m² with nothing but carrots and you have 355 plants to thin and harvest; fill the same 6.4 m² with nothing but courgettes and you have 7.
That ratio is why a crowded plan is not an arithmetic error. Tick all 12 crops on an 8 m² plot and each one gets about 0.53 m²: potatoes still fit 1 plant, carrots fit 29, and courgettes — which want 0.81 m² — round down to 0. The breakdown prints that zero instead of hiding it, so you can see which crop is the one asking for more ground than your plot has.
UK Last Frost Dates And What They Change
Every date on this page is anchored to four broad UK bands: South England and South Wales around 8 April, Midlands and Northern England around 20 April, Scotland Lowlands and Northern Ireland around 1 May, and Scotland Highlands and exposed areas around 20 May, per GardenFocused's UK frost date guide and Glorious Garden's postcode-level guide. That is 6 weeks between the first band and the last, which is the difference between sowing carrots on 11 March and sowing them on 22 April.
Sow offsets are measured from that regional date rather than from the calendar month. Carrots, lettuce and peas are scheduled 4 weeks before the last frost because they tolerate a cold snap, while tomatoes start 6 weeks before it under cover and are only planted out once the frost has passed. A plot in the Highlands therefore runs the same crop list roughly 6 weeks behind a plot in Kent, without a single date being edited by hand.
Succession Sowing: More From The Same Bed
Radishes are ready 4 weeks after sowing and lettuce takes 8 weeks, so a crop sown once in March stops producing long before the plot stops working. Sowing a small batch every 2 to 3 weeks keeps the same bed giving: five radish sowings 3 weeks apart spread harvests across 12 weeks from a bed that only ever holds 0.0045 m² per plant.
The default plan shows the same pattern on a real plot. Its 17 lettuces are cut from 6 May and its 71 carrots from 3 June, while 4 potatoes are not lifted until 24 June and the 42 onions run to 29 July — quick crops carry the early season and slow ones fill the gap behind them. If you want cuts every week rather than one glut, reserving a fifth of the planting area for a repeat sowing of lettuce, spinach or radish does more than adding a new crop.
How The Planner Decides If Your Plan Fits
"Plan Fits" (green) means every ticked crop got at least one plant from its share, and the assessment names the tightest of them — 4 potatoes from 1.28 m² in the default plan. "Tight For Space" (amber) means at least one crop rounded down to 0, so the plan still works but that crop needs the plot to grow or the selection to shrink. "No Crops Fit" (red) means every crop rounded down to 0, which happens when a very small plot is split too many ways: 0.3 m by 0.3 m gives 0.0144 m² per crop, less than any of the five default crops needs.
The verdict measures space and nothing else. It does not judge whether the mix is nutritionally balanced, whether your soil suits the crops, or whether 4 potatoes is enough for the household — those are decisions the numbers leave with you.
Method And Limits
This tool divides planting area equally between selected crops, converts each crop's published in-row by row spacing into a per-plant area, floors the division to whole plants, and derives sow and first-harvest dates from the region's last-frost date plus fixed week offsets, using reference figures compiled on 7 October 2026 from the sources listed below.
- Assumes an even split. A real plot gives beans a whole row and radishes a border; equal shares are a starting point, and the scenario table shows what happens when the area or the path allowance changes.
- Assumes one season, one plan. Crop rotation, companion planting, soil fertility, shade and raised-bed depth (the RHS recommends 45 cm for vegetables) are not modelled at all.
- Spacing is one figure per crop, not a range. Courgettes are fixed at 90 cm and runner beans at 23 cm in the row, where published guidance runs 60–90 cm and 20–30 cm; a tighter spacing raises the number of plants the same area could hold.
- Dates use one representative timing per crop. A seed packet for a specific variety can sit 2 weeks either side of the figure shown here, and no greenhouse, cloche or polytunnel adjustment is applied.
- Harvest figures are first dates only. Nothing here models yield in kilograms, how long a crop keeps producing, or the date the plot finishes for the year.
- Path allowance is a user assumption, not a published rule. 0% suits a raised bed you reach across and 25–30% suits paths on all four sides; the default 20% sits between them.
Figures checked .
Frequently Asked Questions
How does the planner work out how many plants fit?
It splits your planting area by the number of crops you tick, then divides each crop's share by its per-plant footprint — in-row spacing multiplied by row spacing. A 1.28 m² lettuce share at 0.075 m² per plant gives 17 plants, while the identical 1.28 m² potato share at 0.285 m² per plant gives 4. Fractional plants are rounded down, because you cannot buy half a seedling.
What does the path allowance actually change?
It removes a set share of the plot from cultivation before anything gets divided up. The 20% default on an 8 m² plot leaves 6.4 m² for crops; setting it to 0% for a raised bed you reach across leaves the full 8 m² and raises the plant count from 176 to 220 in the default plan. A plot worked on foot with access paths on all four sides usually wants 25% to 30%.
Why has my courgette come out as 0 plants?
Courgettes take 0.81 m² each, because 90 cm by 90 cm is the spacing they need to fill out. If the share left after dividing by your crop count is smaller than that, the row rounds down to 0 rather than squeezing in a plant that will not crop — the breakdown shows the zero so you can see it. On the default 8 m² plot, six crops would still leave 1.07 m² each and a courgette would fit.
Are these sowing dates right for my postcode?
They are anchored to one of four broad UK bands, not to a postcode forecast. A sheltered south-facing plot can run 2 to 3 weeks earlier than its regional figure, and a low-lying frost pocket can run later, so treat the dates as a planning anchor and let the forecast override them. Switching region in the inputs moves every date on the page by the difference between the bands — up to 6 weeks between South England and the Scottish Highlands.
Can I plan an allotment with this, not just a raised bed?
Yes — any rectangular area works. A 10 m by 6 m half-plot is 60 m², and with a 25% path allowance it plants 45 m², which is 2,500 carrots or 55 courgettes at the spacings used here. For an L-shaped or triangular plot, enter two dimensions that multiply to roughly your real area; the maths only ever uses the total.
Does it handle crop rotation, pests or companion planting?
No. It plans one season's space and timing. Rotation is a next-year job: keep potatoes and the crops that follow them moving around a four-year cycle, as the RHS vegetable guidance describes, and keep this season's plan as the record of what grew where.
Why is my seed packet's date different from the one shown here?
Packets give a range for one specific variety and usually separate "sow under cover" from "sow direct". The planner uses a single representative week offset per crop so 12 crops can be compared on the same scale, then anchors it to your region's last-frost date. Use the packet when it disagrees: it knows the variety, this tool only knows the spacing and the region.
Sources
- RHS — Vegetables: growing guides, spacing and rotation
- RHS — How to make a raised bed (45 cm depth)
- RHS — Creating your garden plan
- GardenFocused — UK, Ireland and France last frost dates
- Glorious Garden — UK last frost date by postcode
Last updated: 2026-10-07. This page gives a planning estimate only and is not horticultural advice.
About this tool
Created and maintained by CoryVu. Read how we check our tools and consult the sources and assumptions on this page.
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