Calculate days to maturity from sowing to germination, germination to maturity, and adjustments for growing conditions and harvest stage.
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Days To Maturity Formula
The days to maturity calculation adds the time from sowing to germination, the time from germination to maturity, and any adjustment for real growing conditions or the harvest stage you want.
DTM = S + G + M
- DTM = days to maturity
- S = number of days from sowing to germination
- G = number of days from germination to maturity under optimal conditions
- M = adjustment for growing conditions and desired stage at harvest, in days
If one value is missing, the calculator rearranges the same formula:
S = DTM - G - M
G = DTM - S - M
M = DTM - S - G
To use the calculator, enter exactly three of the four values. If you leave Days to Maturity blank, it totals the three parts. If you leave S, G, or M blank, it subtracts the other known values from the total days to maturity.
Common Germination and Maturity Timing
These ranges are general planning values. Seed packet information, variety, soil temperature, light, water, and season length can change the actual number of days.
| Crop | Typical sowing to germination | Typical days to harvest from sowing |
|---|---|---|
| Lettuce | 2 to 10 days | 30 to 70 days |
| Radish | 3 to 7 days | 20 to 35 days |
| Carrot | 6 to 21 days | 60 to 80 days |
| Tomato | 5 to 10 days | 60 to 100 days |
| Bean | 5 to 10 days | 45 to 65 days |
Adjustment Values for Growing Conditions
The adjustment value can be positive or negative. Add days when conditions slow growth. Subtract days when you plan to harvest earlier than full maturity.
| Situation | Typical adjustment | How to enter it |
|---|---|---|
| Cool weather slows growth | +5 to +20 days | Enter a positive number |
| Poor light, water stress, or low fertility | +3 to +15 days | Enter a positive number |
| Harvesting baby greens or young vegetables | -5 to -30 days | Enter a negative number |
| Ideal growing conditions | 0 days | Enter 0 |
Example
Example 1: Calculate days to maturity
A crop takes 7 days from sowing to germination. It takes 55 days from germination to maturity under optimal conditions. Cool weather is expected to add 8 days.
DTM = 7 + 55 + 8 = 70
The estimated days to maturity is 70 days.
Example 2: Calculate the adjustment
A seed packet lists 65 days to maturity. Germination takes 6 days, and the crop normally needs 54 days from germination to maturity. You want to find the implied adjustment.
M = 65 - 6 - 54 = 5
The adjustment is 5 days, meaning conditions or harvest timing add 5 days beyond the optimal growth period.
FAQ
What does days to maturity mean?
Days to maturity is the estimated number of days until a crop reaches the harvest stage. It may refer to days from sowing or days from transplanting, depending on the seed packet or crop guide. This calculator treats days to maturity as the total of sowing to germination, germination to maturity, and any adjustment you enter.
Can the adjustment value be negative?
Yes. Use a negative adjustment when you plan to harvest before full maturity, such as baby lettuce, small carrots, or young greens. Use a positive adjustment when cold weather, stress, poor light, or other conditions are likely to delay harvest.
Why is my calculated result different from the seed packet?
Seed packet maturity dates are usually based on a specific variety grown under favorable conditions. Your actual result can differ because of soil temperature, planting date, daylight, water, fertility, pest pressure, and whether you are growing from seed or transplant. The adjustment field lets you account for those differences.
