Seed packets contain an enormous amount of useful information compressed into a very small space. For experienced gardeners, that information is second nature. For beginners, a seed packet can look like a wall of tiny text, cryptic symbols, and numbers that seem to assume you already know what they mean.
This guide decodes every element on a seed packet — front and back — so you can walk into a garden centre, pick up any packet, and understand exactly what you are buying, when to plant it, how to plant it, and what to expect. Once you can read seed packets confidently, you have a portable reference guide for every crop you grow.
The Front of the Packet
The front of a seed packet typically displays the plant name, a photograph or illustration, and key growing information at a glance. Here is what to look for.
Plant name: Most packets list both the common name and the botanical or Latin name. The botanical name matters because common names vary regionally. What one company calls cilantro, another might call coriander — the botanical name Coriandrum sativum removes ambiguity. The variety name follows, usually in single quotes — for example, 'Brandywine' or 'Sugar Snap.' Different varieties of the same species can have dramatically different characteristics, so paying attention to variety names helps you choose exactly the traits you want.
Seed count or weight: Packets list either the approximate number of seeds or the weight of seeds inside. Seed counts help you plan how many plants you will get. Weight-based measurements are more common for very small seeds like lettuce or carrots where counting individual seeds is impractical.
Packed for year: Seeds have a limited viability window. Most vegetable seeds remain viable for two to five years if stored properly, but germination rates decline over time. The packed-for date tells you how fresh the seeds are. Buying packets packed for the current year maximises germination rates. Older packets can still work but may have lower germination, so sow more thickly to compensate.
Days to Maturity
This number tells you approximately how many days from planting to harvest. It is one of the most useful pieces of information on the packet, but it requires context to interpret correctly.
For direct-sown crops — seeds planted directly in the ground — days to maturity counts from the date of sowing. For transplanted crops — seedlings started indoors and moved outside — days to maturity counts from the date of transplanting, not from seed sowing. This is an important distinction. A tomato variety listed at 75 days to maturity means 75 days from when the transplant goes into the garden, not 75 days from when you started the seed indoors. Add six to eight weeks of indoor growing time to get the true seed-to-harvest timeline.
Days to maturity is an estimate based on ideal growing conditions. Cool weather, poor soil, insufficient light, or water stress can all extend the actual time. Use the number as a planning tool, not a guarantee. It is especially useful for planning succession plantings and calculating whether you have time to squeeze in a late-season crop before your first frost. For guidance on starting seeds indoors to get a head start on the season, see the seed starting indoors guide.
Sowing Depth
The recommended sowing depth tells you how deep to bury the seed. This is critical because planting too deep or too shallow is a common cause of poor germination.
The general rule is to plant seeds at a depth of two to three times their diameter. Tiny seeds like lettuce, basil, and carrots are barely covered — just pressed into the soil surface and dusted with a fine layer. Medium seeds like beans, peas, and squash go about one to two inches deep. Large seeds like corn and sunflowers go one to two inches deep. The seed packet gives you the specific recommendation for that variety, which accounts for any exceptions to the general rule.
Some seeds require light to germinate and should not be covered at all — just pressed onto the surface of moist soil. The packet will note this. Lettuce, some herbs, and many flower seeds fall into this category. Covering light-dependent seeds with soil prevents germination entirely.
Spacing: Between Seeds and Between Rows
Spacing recommendations appear in two forms: within-row spacing and between-row spacing. Within-row spacing is the distance between individual plants in the same row. Between-row spacing is the distance between adjacent rows.
Some packets list a sowing spacing and a thinning spacing. You sow seeds at the closer spacing, then thin the weakest seedlings once they emerge to achieve the wider final spacing. Thinning feels wasteful, but overcrowded plants perform poorly — it is better to have fewer well-spaced plants than a dense tangle competing for resources.
These spacing recommendations assume traditional row planting. If you use raised beds or intensive planting layouts, you can often reduce row spacing while maintaining within-row spacing, since you access beds from the sides rather than walking between rows.
Light Requirements
Seed packets indicate the light needs of the mature plant using standard terms: full sun, part sun, part shade, or shade. Full sun means six or more hours of direct sunlight per day. Part sun means four to six hours. Part shade means three to six hours with protection from intense afternoon sun. Shade means fewer than three hours of direct sun.
For most vegetable seeds, the requirement is full sun. Leafy greens and a few root vegetables are exceptions that tolerate part shade. If your garden has limited sun exposure, prioritise planting sun-loving crops in your brightest spots and fill shadier areas with lettuce, spinach, and herbs.
Hardiness Zone and Climate Information
Some seed packets include a USDA hardiness zone range, particularly for perennials, herbs, and crops that overwinter. The USDA hardiness zone system divides North America into zones based on average annual minimum winter temperatures. Zone 3, for example, has minimum temperatures of minus 40 to minus 30 degrees Fahrenheit, while zone 9 has minimums of 20 to 30 degrees.
For annual vegetables planted in spring and harvested before frost, the hardiness zone is less directly relevant — what matters more is your frost dates and growing season length. But for perennial herbs like rosemary and lavender, or for overwintering crops like garlic, the zone rating tells you whether the plant will survive your winters.
The packet may also include timing guidance relative to frost dates: plant after last frost, plant two weeks before last frost, or start indoors six to eight weeks before last frost. These instructions are more actionable than zone numbers for annual crops. Know your local last frost date and work backward from there.
Germination Rate and Testing Date
Some packets print the germination rate — a percentage indicating what proportion of seeds are expected to sprout under ideal conditions. A germination rate of 85 percent means about 85 out of every 100 seeds should germinate. This number was determined by testing, and the testing date is usually listed alongside it.
A high germination rate — 80 percent or above — is standard for fresh, quality seeds. If the germination rate is lower, or if the testing date is more than a year old, sow more seeds than you need and plan to thin. Stored seeds naturally lose viability over time, so an 85 percent germination rate at the testing date may be 70 percent or lower a year or two later.
This information is also relevant if you plan to save seeds from your harvest. Understanding germination rates helps you know how many saved seeds to plant the following year to ensure adequate plant populations.
Organic, Heirloom, Hybrid, and Treated Designations
Seed packets often carry one or more designations that describe how the seeds were produced.
Organic means the seeds were grown following certified organic practices — no synthetic fertilisers or pesticides. If growing organically matters to you, look for the organic certification label. Organic seeds are not inherently superior in germination or production, but they align with organic growing principles from seed to harvest.
Heirloom or open-pollinated means the variety has been passed down through generations of growers and breeds true from saved seed. If you save seeds from an heirloom tomato, the next generation will be virtually identical to the parent. Heirloom varieties are essential for seed saving and often have superior flavour, though they may sacrifice uniformity or disease resistance compared to modern hybrids.
Hybrid (often marked F1) means the variety was created by deliberately crossing two specific parent varieties. Hybrids often have superior vigour, uniformity, disease resistance, and yield. The trade-off is that seeds saved from hybrid plants will not breed true — the next generation will be a random mix of the parent traits. If you want to save seeds, choose open-pollinated or heirloom varieties.
Treated means the seeds have been coated with a fungicide to prevent rotting in cold, wet soil. Treated seeds are usually dyed a bright colour — often pink or blue — as a visual indicator. If you prefer untreated seeds, most organic and many conventional seed companies offer them. Treated seeds are not harmful to the garden but are not permitted in certified organic growing.
Putting It All Together: A Sample Packet Reading
To demonstrate how all this information works in practice, here is a hypothetical seed packet reading for 'Sugar Snap' peas.
Front of packet: Pisum sativum 'Sugar Snap,' snap pea, approximately 100 seeds, packed for 2025. Photo shows plump, green pods on a vine.
Back of packet: Direct sow two to four weeks before last frost. Sowing depth: 1 inch. Spacing: 2 inches apart in rows 24 inches apart. Thin to 4 inches apart. Days to maturity: 58 days. Light: full sun to part sun. Germination rate: 90% tested January 2025. Provide support — vines reach 5-6 feet. Successive plantings every 2 weeks extend the harvest. Inoculant recommended for best nitrogen fixation.
From this packet, you learn: plant outdoors in early spring before your last frost, push seeds one inch deep, space them two inches apart initially and thin to four inches, provide a trellis or support, expect to harvest about two months after planting, and consider using a legume inoculant to enhance the natural nitrogen-fixing bacteria that peas support. That is a complete growing plan from one small packet.
Frequently Asked Questions
What does pelleted seed mean?
Pelleted seeds are tiny seeds coated in a clay or similar material to make them larger and easier to handle. This is common with very small seeds like carrots, lettuce, and petunias, which are otherwise difficult to sow evenly. The coating dissolves when watered, exposing the seed inside. Pelleted seeds are more expensive per seed than raw seeds, but the ease of precise spacing often justifies the cost, especially for beginners who find it frustrating to sow tiny seeds evenly.
Are more expensive seed brands worth the higher price?
Quality does vary between seed companies, but price alone is not a reliable indicator. What matters most is germination rate, freshness (packed-for date), and whether the variety is suited to your climate. Many smaller, regional seed companies sell excellent seeds adapted to local conditions at reasonable prices. Large national brands are generally reliable as well. Where premium brands sometimes justify higher prices is in the breadth of their heirloom and specialty variety selections, not in the inherent quality of common varieties.
Can I plant seeds that are a year or two past the packed-for date?
Yes, with the understanding that germination rates decline over time. Most vegetable seeds remain viable for two to five years if stored in a cool, dry, dark place. Onion and parsnip seeds lose viability fastest — often just one to two years. Tomato, pepper, and cucumber seeds can remain viable for four to five years or more. If using older seeds, sow more thickly than the packet recommends to compensate for lower germination, and do a small germination test first: place ten seeds on a damp paper towel in a sealed bag, keep it warm for a week, and count how many sprout.
What if the seed packet instructions conflict with other gardening advice I have read?
Seed packet recommendations are conservative guidelines designed to work across a wide range of conditions. Local gardening advice — from extension offices, experienced local gardeners, or region-specific guides — may differ because it accounts for your specific climate, soil, and growing season. When in conflict, local knowledge usually wins. The seed packet gives you a safe baseline; local experience fine-tunes it. If you are brand new and have no local guidance, following the packet exactly will give you good results in most cases.