"Days to maturity" is an average estimate. It starts when the plant is actively growing in the garden. Seed packets provide instructions on how to start your seeds, but the actual growth timeline can vary.
For direct-sown seeds, the days to maturity count begins once the seeds have sprouted and developed their first true leaves. For indoor-sown seeds, the clock starts after the plants have been transplanted into the garden and have started growing, usually about a week after transplanting.
Since indoor growing conditions like light, temperature, humidity, and watering can differ for everyone, the time it takes to grow plants with 6-8 leaves indoors varies. Growth indoors is typically slower than outdoors due to less optimal conditions. However, once transplanted into the garden, plants grow more vigorously in the sun and under ideal conditions.
Counting days to maturity from the transplant date provides a more accurate timeline for when to expect harvest, as outdoor conditions are more consistent with the plant's needs.