Garden Calendar – What It Is, What to Sow When, and Why an App Beats a Paper Calendar

What is a garden calendar?

A garden calendar (also called a planting calendar or sowing calendar) is a schedule of all garden tasks laid out by month or week. It covers four main event types:

• Indoor sowing – when to start seeds inside before transplanting outdoors
• Direct sowing – when to sow seeds straight into the ground or outdoor containers
• Planting out – when to transplant seedlings, plant bulbs and bare-root stock
• Harvesting – when to expect crops and how long you can leave them before quality drops

A good garden calendar eliminates the most common gardener question: "Is it safe to sow / plant this yet?"

What to sow and plant when – month by month

The following guide covers a temperate climate (UK / Central Europe, hardiness zones 6–8). Dates may shift 2–3 weeks earlier or later depending on your exact location.

January – February: earliest indoor sowings

The garden is dormant, but windowsills and heated greenhouses come alive. Plants with the longest growing cycles go in first:

• Celeriac and celery – need 10–12 weeks indoors, so sow in January or February
• Onions from seed – slow to germinate, start from mid-February
• Peppers and aubergines – especially in cooler regions; 10–12 weeks of seedling time needed

March: tomatoes and intensive indoor sowing

• Tomatoes – classic indoor sowing window: late February to mid-March (6–8 weeks before planting out)
• Cabbages, broccoli, cauliflower – sow under cover from March
• Lettuce, spinach, kale – direct sow under fleece or into a cold frame from March
• Broad beans – frost-hardy; can be direct-sown from March

April: first outdoor sowings

April is deceptive — warm days can be followed by frosty nights. Safe to sow directly outdoors:

• Carrots, parsley, parsnips – prefer cool soil for germination
• Beetroot – direct sow from mid-April
• Peas and mangetout – tolerates light frost
• Potatoes – plant from late April once ground frost risk drops

May: planting out tender crops

Once your last frost date has passed, it's safe to plant warm-season crops outdoors. In the UK this is typically mid-to-late May; in continental Europe often after mid-May.

• Tomatoes, peppers, aubergines – after last frost date
• Courgettes, squash, cucumbers – direct sow or plant seedlings from mid-May
• French and runner beans – direct sow outdoors from May
• Sweetcorn – sow once soil reaches 12°C

June – July: successional sowing and management

• More lettuce, radishes, dill – sow every 2–3 weeks for continuous harvests
• Chinese cabbage and pak choi – sow from mid-July (avoids bolting in heat)
• Endive and chicory – sow seedlings in June–July

August – September: autumn and overwintering crops

• Kale, spinach, lamb's lettuce – direct sow from August
• Garlic – plant from September to mid-October
• Overwintering onion sets – plant in September

The traditional garden calendar – what works and what doesn't

Printed planting calendars and books with sowing date tables have one clear advantage: simplicity. Pick it up, check the month, sow. For generations that was enough.

The problem is that a printed garden calendar assumes average weather for an average region. It has no idea that:

• this April is running 3 weeks colder than usual
• May is forecast to be dry and unusually warm
• your last frost date is a week later than the nearest town
• you're planning to plant out tomatoes the very evening a 0°C night is forecast

A printed calendar stays silent. An app warns you.

Why a gardening app beats a paper calendar

1. It knows your specific plants, not "vegetables in general"

A book says "sow tomatoes March–April." But which tomatoes — early, outdoor, or greenhouse? A variety with 60 days to maturity or 90? An app knows your plants — it calculates your sowing date based on the specific variety and the specific spot in your garden.

2. It factors in the long-range forecast

A smart garden calendar in an app compares your planned dates against weather forecasts. If you're planning to transplant tomato seedlings next Tuesday and the forecast shows nights below 5°C for the following week — the app sees it and can suggest rescheduling.

A printed garden calendar can never do this. It's static by definition.

3. It warns you about frost

Late spring frosts are every gardener's nightmare — they destroy seedlings planted too early, damage fruit tree blossom, set back tender crops by weeks. An app can monitor temperature forecasts and warn you several days in advance before a frost event hits. No printed calendar has ever offered this.

4. It adapts dates to your actual location

Last frost date in Cornwall might be early April; in northern Scotland it's late May; somewhere in the Alps it could be June. One printed calendar can't handle all these differences accurately. An app knows your location and calculates dates for you — not for some average regional assumption.

5. It generates a weekly task list automatically

Instead of scanning an entire year's calendar and writing out your to-dos, the app generates this week's and next week's tasks for you. You check your phone in the morning and see: "water tomatoes today, fertilise cucumbers tomorrow, harvest beans on Friday." No paper calendar gives you that dynamic task list.

Are there downsides to app-based garden calendars?

Honestly, one. Setup takes a few minutes — you need to add your plants to the planner before the system can calculate anything. A printed calendar requires zero configuration.

But that time pays back immediately. Once your garden is set up, you have a personalised calendar for the whole season — and for every following year, since perennial plants carry over automatically.

How to get started with a garden calendar in the app

1. Open Gardener Planner and draw your beds in the visual planner
2. Add your vegetables — click a plant from the list and place it on the bed layout
3. Go to the Calendar — the app automatically generates sowing, planting, feeding and harvesting tasks
4. Enable notifications — to receive frost warnings and task reminders

No need to buy a separate garden calendar, no spreadsheets to maintain, no dates to memorise. The app handles it.