How to Read a Seed Catalog

Learn the key terms and symbols and you'll be on your way to growing your best-ever garden.
Antique seed catalog

Antique seed catalog

Seed catalogs, like these antiques from 1887 and 1923, are packed with gardening tips and irresistible illustrations.

Photo by: Photo by Lynn Coulter

Photo by Lynn Coulter

Seed catalogs, like these antiques from 1887 and 1923, are packed with gardening tips and irresistible illustrations.

It’s hard to resist seed catalogs. All those glossy, color pictures make you want to plant everything you see. But if you don’t know how to read a catalog—that is, how to interpret its symbols and abbreviations—you can wind up with plants that won’t thrive in your garden. That's a waste of time and money.  

Instead of ordering whatever catches your eye, start by thumbing through the catalog for an explanation of its codes. You might see symbols for groundcovers, organic seeds, plants that attract butterflies or take full sun and other categories.  

Also look for the meanings of abbreviations. PM, for example, might stand for a plant that resists powdery mildew, while VFN means it resists Verticillium and Fusarium wilts (diseases caused by fungi in the soil) and nematodes (microscopic worms in the soil). 

USDA Plant Hardiness Zone Map

USDA Plant Hardiness Zone Map

Use this USDA Plant Hardiness Zone Map, provided by the U.S. Dept. of Agriculture (and in the public domain), to help determine which plants are likely to survive the winter in your area. The map divides the country into 12 gardening zones, based on the average lowest temperatures in each. Remember: the map is a guide. Many other factors determine whether or not a plant will overwinter in your garden, including humidity, sunlight, soil type, and wind.

Photo by: Image courtesy of the U.S. Department of Agriculture

Image courtesy of the U.S. Department of Agriculture

Next, look for a map to find your hardiness zone. Most catalogs use the USDA Zone Hardiness map, which is based on the average lowest winter temperature in 11 regions across the U.S. Once you identify your zone, you can choose plants that should overwinter in your area. (Annuals are the exception, since they die at the end of their first growing season in your garden.)

If your catalog doesn’t include a map, look for the USDA Plant Hardiness Zone Map online. 

Some catalogs use different maps. You might see the Heat Zone Map, created by the American Horticultural Society. It uses average high temperatures to designate gardening regions across the country. The Sunset Climate Zone Map is used less often. It uses many more factors to define its zones, such as a region’s elevation, latitude and microclimates. 

Now you’re ready to make a list of plants that can thrive in your garden. 

Here are some important terms you may come across: 

Maturity, or days to harvest: the average number of days it takes from the time you sow seeds or transplant seedlings until your first harvest. Remember, this is just an average that can be affected by weather and other growing conditions. 

Early, midseason, late season: These terms are sometimes used instead of “maturity.” They refer to approximate harvest times during the growing season. 

Organic: These are seeds or plants from a certified-organic source that have never been treated with chemicals or pesticides. Organic also means the products you're buying have not been genetically modified.  

Hybrid: Varieties that have been created by cross-pollination are called hybrids. Cross-pollination can produce plants with desirable characteristics, such as a sweet taste in watermelons or big, colorful blooms in zinnias. 

F1 means a first-generation hybrid, while F2 refers to the second-generation. 

You can’t save the seeds of most hybrids, because most hybrid seeds are either sterile or they don't grow true-to-type—that is, they don't produce baby plants that look like the parent. There are a few exceptions to this rule. 

Perennial: A plant that comes back year after year, usually going dormant in the winter and growing back the following spring. 

Biennial: A plant that grows and stores energy during its first growing season and blooms in its second season. 

Heirloom: Generally speaking, this is a variety that’s been around since before World War II. Heirlooms are open-pollinated (shown as OP in some catalogs), which means you can grow the seeds and get new plants that are almost identical to the parent plants. Since heirlooms have survived and adapted to their growing conditions over a long period of time, many are usually resistant to diseases and pests. 

Variety: A version of a plant; each variety has different characteristics. The pepper section of your seed catalog, for instead, may list such varieties as ‘Sweet California Wonder’ or ‘Hot Mariachi’. 

Cultivar: Sometimes used in place of “variety,” a cultivar means a cultivated variety.

Determinate and indeterminate: Often used to describe tomatoes, "determinate" means a plant that bears all its crop at once and stops growing at a certain height. Indeterminate plants keep growing and bearing throughout the season. Determinates are better choices for containers or gardens with limited space.

AAS: A variety that won an All-America Selections award for outstanding performance in the garden.

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