Reference
How to Read a Seed Packet
The short answer
A seed packet is a compressed growing guide: it tells you how deep and how far apart to sow, how many days until seedlings emerge, and 'days to maturity', the average time from planting to first harvest. The catch with days to maturity is when the clock starts: for crops sown directly in the garden it counts from seeding, but for crops usually set out as transplants (like tomatoes) it counts from transplanting outdoors, not from the day you sowed the seed indoors.
Two other lines are easy to miss. The germination rate is the percentage of seeds that sprouted in the company's tests, so you know how thickly to sow. The 'packed for' or sell-by date tells you the season the seed was packaged for; seed packed for the current year gives the most reliable germination, and older packets should be germination-tested before you rely on them.
The map of a seed packet
The front usually carries the common name, variety name, a photo, and sometimes the seed count or weight. The back is the working side: planting depth, spacing between seeds and between rows, days to germination (emergence), days to maturity, light and water needs, when to sow relative to your last frost, and often thinning instructions and a brief description of the plant.
Regulatory lines matter too: packets carry the year the seed was packed for (or a sell-by date) and a lot number, and often the germination percentage from the company's testing. None of it is filler; a packet read carefully replaces a surprising amount of guesswork.
- Depth and spacing: how deep to sow, distance between seeds and between rows
- Days to germination: how long until you should see seedlings emerge
- Days to maturity: average time to first harvest (see below for when it starts)
- Germination rate: percent of seeds that sprouted in testing
- Packed-for / sell-by date and lot number: how fresh the seed is
Days to maturity: when does the clock start?
'Days to maturity' (or 'days to harvest') is the average number of days from planting until first harvest, but it is measured from different starting points depending on the crop. For direct-sown crops like beans, carrots, or lettuce, it counts from sowing in the garden. For crops normally grown from transplants, like tomatoes and peppers, it counts from the day the transplant goes into the garden, which is why a '75-day' tomato really occupies your season for far longer than 75 days once you add the indoor seedling weeks.
It is also an average, not a promise. Cool weather, poor fertility, drought, and shade all stretch it. The practical use is comparison and season math: check the days to maturity against the time left before your first fall frost to see whether a crop can finish, and pick shorter-season varieties when the math is tight.
Germination rate and the packed-for date
The germination percentage tells you what fraction of seeds sprouted under test conditions. A high rate means you can sow close to your final spacing; a lower rate means sow extra and thin later. Fresh seed packed for the current season is the safest bet, which is what the 'packed for' date is for.
Seed does not die the day the packet expires, though. Stored cool and dry, many vegetable seeds stay usable for years, and a quick paper-towel test tells you whether an old packet is worth sowing. See our guides on testing seed viability and on storing seeds for how long each crop's seed typically lasts.
✔ Before tossing last year's packets, run a 10-seed paper-towel germination test. If 7 of 10 sprout, just sow a little thicker than the packet suggests.
Putting it together: a 30-second pre-sowing check
- 1Check the date — Is the seed packed for this year? If older, plan a germination test or sow extra.
- 2Do the season math — Days to maturity vs. days left in your season. Remember the transplant-crop clock starts at transplanting.
- 3Note depth and spacing — Sowing too deep is a classic cause of no-shows; small seeds are usually sown shallow.
- 4Mark the calendar — Use days to germination to know when to expect seedlings, so you know when something has gone wrong.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Illinois Extension — Seed Packets (Prairies to Perennials) — Packets list depth to plant seeds, spacing between seeds and rows, number of days until seedlings emerge (germinate), days to harvest, year seed is packed for and sell-by date, plus light/water needs and hardiness information.
- University of Maryland Extension — Reading a Seed Packet (Rachel Rhodes) — Days to maturity is the average days from planting to harvest; for direct-sown seeds it counts from seeding, for indoor-started crops it counts from transplanting outside; maturity time is influenced by temperature, fertility, moisture, and sun exposure.
- West Virginia University Extension — Understanding Your Seed Catalog — Seed packets include common name, number or weight of seeds, country of origin, year packed for and sell-by date, lot number, and company name and address; germination percentage comes from company testing.