Decoding Catalogs from Top Seed Companies

How to Understand Seed Catalogs Online or in Print

Decoding Catalogs from Top Seed Companies

Shopping for seeds sounds easy, doesn’t it? But when you open catalogs from the top seed companies, you’re assaulted with foreign terms. VF, OP, F1, PVY. How do garden zones help you determine when to plant vegetable seeds? What’s an indeterminate tomato? How do you find heirloom seeds? And why can’t you plant two different corn varieties side by side?

Colorful pictures and glowing descriptions from top seed companies promise a bountiful, blooming garden. But those pictures are enhanced, highlighting the best examples the photographer could find. “New” and “improved” mean little to your individual garden, and of course the description is written to encourage sales. To determine if a plant will work for your garden, read into the technical terms such as zones and growth habit.


One of the first things you may notice beside any seed description from top seed companies is a little picture. They vary between catalogs but at the bottom of the page you’ll usually see a key for what the icons mean. For instance, a snowflake might mean the plant is cold-tolerant and a picture of a flower pot means it’s good for containers. A red, white, and blue shield means the variety is an All-America Selection Winner.


Pineapple won’t grow in Minnesota and spinach won’t likely flourish in Hawaii. Growing arugula from seed is more difficult in some zones. You can eliminate a lot of gardening heartache if you research your zone before you order plants and seeds. Refer to trusted maps such as the USDA Plant Hardiness Zone Map, identify the number fitting your location, and purchase crops recommended for your area.

Soil Type

Is your soil sandy, silty, clay, or loamy? Because it’s so well aerated, sand loses moisture quickly. Plants that flourish in drought-stricken areas do well in sand. Smooth, slippery silt holds moisture for long periods of time but it also drains poorly. Amend silt with compost or plant grasses and vines. Heavy, dense clay can be tough for moisture to penetrate but it also holds water and nutrients well after they break through. Colorful flowers like wisteria and rhododendrons do well in clay. Loam has fairly equal quantities of sand, silt, and clay. Though loamy soil may need some amendments, it’s generally the best for crops because it drains well and holds in moisture and nutrients.


Annual, Biennial, Perennial

Annuals sprout fulfill their purposes in life and die within a single growing season. Some crops, such as radishes, only live 30 to 60 days. You might be able to lengthen their lives with season extenders but it won’t be forever. Biennials like parsley take two growing seasons, sprouting and growing in the first year then blooming and producing seeds the second. Perennials live year after year; some plants, like trees, live for centuries. Oregano and grapes are perennials.

Full Sun, Partial Sun, Shade

Shade-grown plants flourish where they get no more than two hours of direct sun per day. Partial shade is between two and four hours, and partial sun requires four to six hours. Though direct sun technically means that the plant requires more than six hours per day, most crops prefer ten or more hours. And remember that “full sun” means “full sun in an area that often gets cloud cover.” If you live in a harsh desert, you may need to provide a little shade.


To get the best harvest, observe spacing recommendations on the plant’s tag or description. Spacing refers to the distance from the center of one plant to the center of the next. Planting too close together can cause competition, resulting in small vegetables or fewer fruit.

Botanical Names vs. Common Names

Most of the top seed companies provide two names for each plant. For instance, a catalog might list butternut squash, followed by cucurbita moschata. The first is the common name and the second is the Latin genus and species. Though beginning gardeners may find this name irrelevant, it is crucial for seed savers or breeders who may not want to cultivate two varieties that can cross. If you’re growing butternut squash from seed, and want to save the seeds from next year, do not grow it beside another cucurbita moschata.

Heirloom vs. Open Pollinated vs. Hybrid vs. GMO

Open-pollinated plants are pollinated through natural methods, such as wind or insects. As long as the plant is not introduced to pollen from other varieties within the same species, offspring will retain the same traits as the parent. OP plants are the most sustainable.

Heirlooms are plants that have been passed to another person by propagating the seeds of that particular species. Though heirloom plants must be produced through open pollination, not all OP plants are heirlooms.

Hybrids are not genetically modified; they are a product of two plants that are deliberately bred together for specific traits. Though F1, the first generation of hybridization, often produces a vigorous plant, the cross is genetically unstable and the offspring of that plant will not be true to variety and will probably also not be as vigorous. Saving seeds from hybrid plants is not recommended.

Genetically modified organisms, or GMOs, have been altered in ways that nature cannot accomplish, which can include inserting genes from other plants or animals. Though seed descriptions may not specifically say whether they are GMO, most top seed companies will disclose whether they sell GMO seeds/plants.


Researching a plant’s habit is important, especially if you’re gardening on a balcony or in a small garden. Top seed companies list the growth habits of tomatoes, beans, squash/pumpkins, cucumbers, and many other plants.

If your beans have a bush habit, they grow on a plant which reaches six to eighteen inches and needs little to no support. Vining/pole beans continuously climb whatever vertical support they can find, blossoming and producing until the season ends.

Squash can grow on a vine that ranges from 10 to 40 feet in length, or on a bush which will only reach out a few feet in each direction. Vining habits need extra room to grow, either on the ground or with vertical support. Within the bush description, you may have a dense or an open habit. Though the dense habit is best for small spaces, an open habit sprawls out and allows easier harvesting.


Among growth habit types are determine and indeterminate. Normally used for tomatoes, the term “indeterminate” refers to a plant which grows, blossoms, and produces fruit until a natural occurrence like a hard frost stops it. This can result in tomato plants that are eight feet tall with massive root systems, requiring a lot of support. Many heirloom tomatoes are indeterminate. Determinate plants reach a certain size, normally three to four feet, then produce fruit all at once. Many patio or paste tomato varieties are determinate.


Days to Maturity

Assessing days to maturity is different plant by plant. Direct-sown vegetables, such as radishes and corn, have a timeline stretching from the day they sprout to when the crop is available to harvest. When the plant is often transplanted after the final frost, such as tomatoes and eggplants, “days to maturity” start counting after the plant is permanently in the ground. So if you’re growing a beefsteak tomato with a maturity of 95 days, add an extra eight weeks to calculate time from seed to transplant. Compare the total days to maturity with your zone. If you live in zone four and have a growing season of fewer than 90 days, growing Hubbard squash can be risky. It requires 110 days or an oxheart tomato which will take at least 140 days between seed and the first ripe fruit.

Sweet Corn

If you want to grow a nice corn on the cob, you may have researched how to grow sweet corn and noticed the abbreviations SU, SE, or SH beside seed descriptions. Ignoring these abbreviations may result in starchy or tasteless corn. Normal types with starch and sugar in the kernel, also called sugary-1, are labeled by SU or SU-1 within catalogs. SH are supersweet, with sugar but no starch, and are shrunken when dry. In between those two classifications are SE, sugar enhanced, which have more sugar than SU but still have a little starch.

If you plant corn of two different classifications within the same short space, the genes will mix as the corn is pollinated. Unlike tomatoes and peppers, where cross-breeds show up within the next generation but does not reflect in the fruit of that specific plant, corn displays crossbreeding immediately because the kernel is the seed. SU varieties should be planted near other SU varieties. You can isolate different classifications with a distance of over 250 feet, a windbreak, or by planting in succession so the one variety does not tassel at the same time that a competing variety produces silk.

Since over 85% of the corn in the United States is genetically modified, shop specifically for heirloom seeds from top seed companies if you want non-GMO corn.


OP means “open pollinated.” F1 refers to the first generation of hybridization. Top seed companies feature All-America Selection Winners (AAS), tested and proven new varieties with superior performance. OG seeds/plants are organic. Other than those, most abbreviations you see in top catalogs refer to disease resistance. You don’t have to memorize them if you keep a guide handy.

Abbreviation Disease Name Types of Plants Affected
A Anthracnose beans and cucumbers
AB/EB Alternaria, or Early Blight carrots and tomatoes
ALS Angular Leaf Spot cucumbers
AS Alternaria Stem Canker tomatoes
B Bacterial Wilt cucumbers
BB Bacterial Blight beans and carrots
BBS Bacterial Brown Spot beans
BLS Bacterial Leaf Spot peppers
BMV Bean Mosaic Virus (one or more races) beans
BR Black Rot pumpkins
BYMV Bean Yellow Mosaic Virus beans
C Cercospora Blight carrots
CMV Cucumber Mosaic Virus (Cucumber Blight) cucumbers and summer squash
CR Club Root Chinese cabbage
CS Cavity Spot carrots
CTM Curly Top Beet Mosaic Virus sugar beets
Cv Cladosporium Leaf Spot spinach
CVYV Cucumber Vein Yellow Virus cucumber, melons
DM Downy Mildew crucifers, grapes, vining vegetables
E Enation Mosaic Virus peas
F Fusarium Wilt (Race 1) melons, peas, tomatoes
F2 Fusarium Wilt (Races 1 and 2) melons, peas
F3 Fusarium Wilt (Races 0, 1, 2) melons
FBR Fusarium Basal Rot onions
FOR Fusarium Crown and Root Rot tomatoes
FY Fusarium Yellows cabbage and Chinese cabbage
HB Halo Blight beans
L/St Gray Leaf Spot tomatoes
LB Late Blight tomatoes
LM Resistant to Leaf Molds A-E tomatoes
LMV Leaf Mosaic Virus lettuce
MDMV Maize Dwarf Mosaic Virus corn
MNCLB ModernNorthern Corn Leaf Blight corn
MR Moderate Common Rust corn
MSCLB Moderate Southern Corn Leaf Blight corn
MSW Moderate Stewart’s Wilt corn
MT0-10 Seeds have been tested for Lettuce Mosaic Virus and none was found in samples of 10,000 seeds or fewer
MT0-30 Seeds have been tested for Lettuce Mosaic Virus and none was found in samples of 30,000 or fewer
N Nematodes tomatoes
Nr Lettuce Aphid lettuce
NCLB Northern Corn Leaf Blight corn
PC Phytophthora Root Rot peppers
PEMV Pea Enation Mosaic Virus peas
PeMV Pepper Mottle Virus peppers
PL Corky Root Rot tomato
PLR Pea Leaf Roll Virus peas
PM Powdery Mildew beans, cucumber, carrot, melon, peas,
pumpkin, summer squash, tomato
PMV Pepper Mosaic Virus peppers
PR Pink Root onion
PRV Papaya Ringspot Virus cucumber, summer squash
PST Bacterial Speck tomatoes
PVY Potato Virus Y peppers
PY Pythium Resistance
R Common Rust asparagus, beans, corn
Rs Corky Root lettuce
S Scab cucumber
SCLB Southern Corn Leaf Blight corn
SM Smut corn
SW Stewart’s Wilt corn
TBSV Tomato Bushy Stunt Virus lettuce
TEV Tobacco Etch Virus peppers and tomatoes
TMV/T Tobacco Mosaic Virus multiple vegetables
TSP Target Spot cucumber
TSWV/SWV Tomato Spotted Wilt Virus peppers and tomatoes
TYLCV Tomato Yellow Leaf Curl Virus tomatoes
V Verticillium Wilt tomatoes
VFN Resistant to Verticillium Wilt, Fusarium, and
multiple vegetables
W Common Wilt multiple vegetables
WMV Watermelon Mosaic Virus cucumber, melon, pumpkin, summer squash
WR White Rust crucifers
ZYMV Zuccini Yellow Mosaic Virus cucumber, summer squash


Now that you have a guide for decoding catalogs, you can browse top seed companies and select varieties which are perfect for your zone, soil, amount of sunlight, and potential diseases in your area.


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