What is “Days to Maturity” on Seed Packets? — Empress of Dirt

Learn what “days to maturity” means in gardening, how it’s calculated, and why it matters—especially for cold-climate gardeners planning their growing season.

If you are new to gardening, learning the difference between annuals and perennials is also helpful.

Days to Maturity

Days to maturity (or days to harvest) refers to the average number of days a plant takes to reach a harvestable stage.

The average number of days a plant takes to reach a harvestable stage.

Depending on the type of plant, this could mean when a vegetable is ready to pick or when a flowering plant begins to bloom.

It’s an estimate to help with garden planning rather than an exact science.

How It’s Calculated

There’s no universal standard, but generally days to maturity is calculated one of these ways:

For seeds sown directly outdoors, counting begins after germination, when the first true leaves appear. “True leaves” are the second set of leaves that appear on seedlings.
For seeds started indoors, counting begins when the plants are transplanted outdoors.

Many seed companies list the definition they follow in the seed catalogs.

Factors That Affect Days to Maturity

While seed packets provide an estimate, actual timing can vary due to:

Temperature fluctuations (warmer conditions can speed growth, while cold slows it).
Sunlight exposure and length of daylight hours.
Soil quality, moisture levels, and overall growing conditions.
Excessive heat or drought, which can slow or halt plant growth.
The natural slowdown of plant growth later in the season as temperatures drop.

This is why it’s smart to always allow a buffer period (of a few weeks), in addition to the estimated days to maturity, when growing plants that produce fruit.

Why It Matters

Estimated days to maturity is especially useful for fruiting plants like tomatoes, zucchini, peas, and watermelon, which need enough time to flower and produce fruit before the growing season ends.

In cold climates with short outdoor growing seasons, estimated days to maturity serve as a crucial guide for determining when to start seeds indoors. By getting plants with a long growing time well-established indoors before the outdoor growing season, they can get on with the business of flowering and fruiting once planted outside.

For leafy greens and vegetables grown primarily for their stems or leaves, such as lettuce or kale, days to maturity is less critical since they can be harvested at almost any stage.

How to Use This Information

Start by looking up the estimated number of frost-free days you get. I’ve listed calculators in the Resources section.

Then, compare that number to the estimated days to maturity for any seed you want to grow, and add a buffer period for insurance.

Do you have time to sow directly outdoors or should you give the seeds a head start indoors?

Resources

Find Your Frost Dates & Hardiness Zone

Plant Hardiness Zones | United States | Canada
These are listed on seed packets and plant tags to guide your choices.

Average Frost Dates | Use this calculator at Almanac.com. Enter your city and state or province to find your first and last frost dates and number of frost-free days.

Ecoregion | Learn about local native plants, animal species, and environmental conditions to make garden choices that benefit your ecosystem.

Learn More: Understanding Frosts & Freezing For Gardeners