Seed Starting Calculator
Work out when to start seeds indoors before the last frost.
Quick answer: enter your details below and click Calculate Sowing Date — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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Enter your details below.
How to use
- Enter your values in the fields provided.
- Click Calculate Sowing Date.
- Read the result and adjust an input if you want a different outcome.
About this tool
Starting seeds indoors means counting backwards from the last frost. Enter the last frost date and how many weeks early the seeds need, and this tool gives the sowing date.
Frequently asked questions
What do I enter to get a result?
Fill in every field with your own numbers or choices, then run the tool. Empty number fields count as zero, so check them before you trust the output.
Can I reuse this result elsewhere?
Yes. The result is calculated in your browser from the values you entered, so you can copy the numbers into your own notes or plan.