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Vegetable gardening guides
Seven guides covering the decisions that actually determine a harvest: how far apart to plant, what to plant next to what, and when to start each crop. Written around frost dates and bed layouts rather than vague seasons.
Square foot gardening spacing chart
How many plants fit per square for 33 crops, a worked 4×4 layout, and the four mistakes that waste squares.
Companion plantingCompanion planting chart
Which vegetables help each other and which to separate — with the evidenced pairings marked apart from the folklore.
Seed startingWhen to start seeds indoors, month by month
A sowing schedule counted back from your own last frost date, with weeks-before-frost timings for 20+ crops.
PlanningVegetable garden layout plans for beginners
Site, size, sunlight and layout — the order to make the decisions in, with 4×4 and 4×8 examples you can copy.
ZonesHardiness zone vs frost date
Zone 8 covers Seattle and northern Alabama. Why your zone doesn't tell you when to plant, and which two dates do.
TomatoesGrowing tomatoes from seed, week by week
Sowing, potting on, hardening off and planting out — timed from your frost date, with the temperatures that decide the crop.
HerbsGrowing basil from seed indoors
Germination temperature, when to pot on, and the pinching habit that turns a leggy seedling into a summer-long harvest.
Free toolsFour garden calculators →
Plants per square foot, raised bed soil volume, plant spacing and a frost-date sowing schedule. No sign-up.
Where to start
If you are building your first bed, read them in this order: layout to decide the site and size, spacing to work out what fits, companion planting to arrange it, and seed starting to put dates against everything.
If you already have beds and the problem is timing rather than layout, skip to hardiness zone vs frost date — it is the misunderstanding behind most crops that fail for no obvious reason.
Reading is planning. This is doing.
Everything in these guides, applied automatically to your own beds. Free on iPhone.
Questions gardeners ask
Is Niwa free to use?
Yes. Niwa is free to download from the App Store, and the core planner — the garden grid, the plant library and the planting calendar — works without paying. Optional in-app purchases unlock additional features.
See it on the App StoreHow many plants fit in one square foot?
It depends on the crop's spacing requirement. A plant needing 3 inches fits 16 per square foot, 4 inches fits 9, 6 inches fits 4, and 12 inches fits 1. Large plants such as vining tomatoes or zucchini need more than one square each. Niwa works this out for you and prints the count straight onto the grid cell.
Plants per square foot calculatorCan Niwa plan a raised bed of any size?
Yes. You set the bed dimensions — 4×4, 4×8, 2×8 or a custom size — and Niwa draws the square foot grid to match. You can keep several beds and several gardens in the app at once and switch between them.
Raised bed plannerHow does Niwa know when I should plant?
Niwa uses your location to find your average last spring frost and first autumn frost, then works backwards from those dates for every crop in your bed. Each plant gets its own sow-indoors, transplant and harvest window on a month-by-month timeline, so the dates are yours rather than a generic zone table.
How the planting calendar worksDoes Niwa warn me about bad companion plants?
Yes. As you place plants on the grid, Niwa puts a green dot between neighbouring squares that benefit each other and a red dot between squares that are better kept apart, so you see the conflict while you are still planning.
Companion planting in NiwaHow much soil do I need to fill a raised bed?
Multiply length × width × depth in feet to get cubic feet, then divide by 27 for cubic yards. A 4×8 bed at 12 inches deep needs 32 cubic feet, roughly 1.2 cubic yards or sixteen 2-cubic-foot bags.
Raised bed soil calculatorDoes Niwa work offline, and do I need an account?
The whole plant library and all your layouts are stored on the device, so the app works with no signal — useful on an allotment. There is no account to create and your garden data is never uploaded to a server.
See what's includedWhich growing zones and countries does Niwa support?
Niwa works worldwide. It recognises USDA hardiness zones in the United States and derives frost dates from your location elsewhere, including the UK, Canada, Australia and Europe.
Find your frost dates and zoneHow is Niwa different from other garden planner apps?
Three things: it is a native iPhone app rather than a desktop planner viewed in a mobile browser, it shows companion-planting conflicts on the grid as you place plants instead of in a separate chart, and it works fully offline with no account.
Compare Niwa with other plannersIs Niwa available on Android?
Not yet. Niwa is a native iPhone app and needs iOS 18.0 or later. An Android version is not currently available.
Read the gardening guides in the meantime