Days to Maturity
The average number of days from transplant date (or from direct sowing, where noted) until a crop is ready to first harvest under normal growing conditions.
Days to maturity (DTM) is the figure on every seed packet that tells you how long to expect before your first harvest. It sounds simple, but it hides enough nuance to cause real planning errors if you take it at face value.
Transplant vs. Direct Sow
The most important thing to know: for crops that are typically started indoors and transplanted (tomatoes, peppers, eggplant, most brassicas), the DTM on the packet counts from the date of transplant into the garden, not from when you sow the seed indoors. A tomato labeled “70 days” takes 70 days from transplant. If you start it indoors 6-8 weeks before transplant, the full time from seeding to harvest is actually 112-126 days.
For direct-sown crops (carrots, beets, beans, peas, radishes), DTM typically counts from the day seeds go in the ground.
Some seed sellers count DTM from the day of germination rather than sowing. When this matters for planning, check the catalog description or call the seed company.
What Affects the Real Number
The DTM on the packet is a baseline measured under controlled trial conditions - usually in a research garden in a specific climate with optimal inputs. Your actual days to maturity will vary based on:
Temperature. Most crops grow faster in warm soil and slower in cool soil. A pepper rated at 75 days in a Pennsylvania trial may take 85 days in a Minnesota summer that stays cooler longer. The same pepper in a Georgia summer may ripen in 65. Growing degree day models give more accurate predictions than calendar days for serious planning.
Variety. Within a species, varieties can range by 20+ days. Early-season tomatoes like ‘Stupice’ or ‘Glacier’ mature in 55-60 days; large beefsteaks like ‘Mortgage Lifter’ take 80-85. The packet DTM is the only number worth trusting for a specific variety.
Soil fertility and watering. Stressed plants are slower plants. Adequate fertility and consistent moisture keep crops tracking toward their rated DTM. A drought-stressed carrot patch will run 10-15 days past its label.
Using DTM for Season Planning
Work backward from your first frost date. If your first fall frost arrives October 1 and you want to direct-sow a crop that needs 60 days to mature, the last safe sowing date is around August 2 - giving you 60 days plus a small buffer for slowing growth as days shorten.
For transplanted crops, add your indoor start time to the transplant-to-harvest DTM to get the full seed-to-table timeline.
When selecting varieties for short-season climates (zones 3-5), DTM is often the deciding factor. A 90-day tomato is essentially impossible to ripen outdoors in zone 4 without a greenhouse or season extension; a 65-day variety is reliable.
DTM and Succession Planting
For crops you want to harvest continuously (lettuce, beans, radishes), DTM tells you exactly how often to plant a new row. Radishes at 25 DTM: plant a row every 2-3 weeks starting 4 weeks before last frost for a continuous supply. Beans at 55 DTM: plant every 2 weeks through early summer for staggered harvests rather than one large glut.