Seed Starting Date Calculator

An over-grown, root-bound seedling held back by cold weather often yields worse than a younger one transplanted on time. Tomatoes and peppers started more than 10 weeks before transplant date typically become leggy, develop thick, hardened stems, and take longer to recover after transplanting. Resist starting heat-lovers prematurely - the few extra weeks inside rarely produce earlier fruit.

Cool-tolerant plants like cabbage, onions, and broccoli can go out on or even a week before the average last frost date. Frost-sensitive crops like tomatoes, peppers, and basil prefer a 1-2 week buffer after the average frost date - both to avoid a late frost and because they want warm soil temperatures (above 60°F) for good root development.

It is how many weeks after the last frost date you plan to actually put the seedlings in the ground. Zero means transplant on the frost date itself. One or two weeks is a common buffer for tender crops. The total indoor time shown is the gap between the sow date and the transplant date - more buffer after frost means a longer indoor stint.

Run the calculator separately for each crop using its own packet-recommended lead time. Write the sow date on the seed packet and on a dedicated calendar page. Stagger sow dates when you have limited bench space - start the slowest crops (peppers, eggplant) first, then work toward faster crops as space opens up from earlier sowings that get transplanted out.