How to Use the Seed Sowing Date Calculator
Hitting a specific harvest date means working backward to figure out when to sow, and it gets confusing once you factor in the transplant step too. This calculator takes your target harvest date, the crop's growth period (total days from sowing to harvest), and the days needed before transplanting seedlings, then works backward to give you both a sowing date and a transplant date.
The growth period printed on a seed packet or seed company listing usually refers to the total days from sowing to harvest readiness. For direct-sow crops like lettuce, just leave the transplant days at 0, and your sowing date becomes your planting date. For crops like tomatoes or peppers that are started indoors first, enter the transplant days too so you get both the sowing date and the date to move seedlings outside.
These dates are based on standard growth periods, so your actual harvest could shift a few days earlier or later depending on your local climate and that season's weather. Building in a one to two week buffer when you plan your sowing schedule makes it easier to absorb unexpected weather swings.
Frequently Asked Questions
Yes — for direct-sow crops, just enter 0 for the transplant days. In that case, your sowing date is also the date you plant directly in the garden.
It's usually printed on the seed packet or the seed company's website as 'days to maturity' or 'days from sowing to harvest.' Actual timing can shift a few days with your local climate, so plan with some buffer.