Seed Catalogs Decoded

Seeds in hand

You might think your gardening friends are crazy for waiting nervously by their mailboxes in the snow, looking for the smallest glimpse of a seed catalog. Like robins and crocus, seed catalogs are one of the earliest signs that spring is just around the corner—gardeners and greenhouse growers everywhere know that when they start to appear, gardening season can’t be far behind.

Maybe you’re one of the lucky few, pacing nervously, awaiting the arrival of those magic books that fill even the most seasoned gardener with a new sense of wonder year after year, but do you know how to read a seed catalog? They’re more than pretty pictures, you know—there are important abbreviations, codes and gardening terminology that you might not even realize you’re missing out on. Let me walk you through a garden catalog or two so you can get the most out of these amazing and useful devices.

Hybrid, heirloom and open pollinated varieties

Hybrid varieties (sometimes designated as F1) aren’t evil, they’re not toxic, they’re not poison, they’re simply hybrids —a cross between two different varieties of beans or tomatoes or what have you. They contain a mix of genes, which makes them unreliable seed producers if you want the exact variety year after year. As with most things in life, there’s a time and a place for everything, and hybrids have their place, especially among beginning growers: they’re more disease resistant, less finicky and generally more reliable producers in less than perfect environments.

Heirlooms and open pollinated varieties make up most of the other seed catalog options, these plants have been developed over many years by carefully selecting the best of a certain variety and breeding those plants together. Heirlooms are the varieties your great grandparents may have grown, though hybrids have been with us a long time. In general, these guys tend to have stronger flavors, colorful fruit and they reproduce themselves faithfully from seed.

It’s not a universal law that heirlooms must taste good, though—that’s something heirloom fanatics tend to overlook. I’ve eaten many a foul tomato that was a heirloom—the white ones are especially horrible, but I digress. Heirlooms have been developed in microclimates, sometimes as specific as a particular backyard garden, and don’t always do well when taken outside of that microclimate. That being said, they’re a challenge and most gardeners love that about heirlooms most of all.

Open pollinated varieties are heirlooms without the pedigree. Often, varieties like Green Zebra tomatoes are lumped in with heirlooms, but these guys lack the long bloodlines of the heirloom varieties. Otherwise, they are very similar—they reproduce themselves faithfully from seed because they were created through crossings of one variety of snap bean or beet to others of the same variety.

Days to maturity

This is one that threw me for a while—it seems so self-explanatory, but it’s really, really not. Days to maturity applies haphazardly across the seed spectrum. Seeds that are typically directly sown into the garden are going to be doing their thing, whatever that is, about this many days after they germinate. If their thing is flowering (because they’re flowers), then expect to see buds swelling and bursting open as your plants approach the Days to Maturity listed in the catalog or on the seed packet.

If, however, your plants are typically used as transplants, like a lot of vegetable crops, you’re looking at the number of days to fruit after you’ve moved your young seedlings into the garden, assuming you’ve had them indoors for the optimal amount of time recommended for their species. So, if you set your tomato seeds to germinating in your greenhouse, then move them up to a bigger pot to grow to transplant size and move them outdoors properly without giving them massive sunburns or transplant shock, you can count from that day. Accuracy depends on you doing everything right from the get-go.

Days to Maturity apply a little differently to plants that will never leave the greenhouse. You can’t use them as a guide to anything, but they will give you some idea which varieties should mature more quickly than others. Since you can provide optimal conditions all the time, annual plants in the greenhouse are often way ahead of their outdoor cousins when it comes to growth and maturity.

Disease resistances

Many seed catalogs and plant tags neglect to explain the one to five letter disease resistance codes, but they all have them. When you look at a plant that has a lot of disease problems, like tomatoes and cucumbers, there may be some letter codes near the name set off in parenthesis or italics. It’s total babble unless you know what you’re looking at—for example Johnny’s Selected Seeds 2014 catalog lists (A, ALS, DM, PM, S) just below the name for the entry for Olympian cucumbers. Different catalogs call resistances out differently, so pay close attention as you flip through the pages.

This particular catalog is pretty good about spreading keys along the seed groups, but they won’t appear everywhere, so I made you a list of the most common resistances you might see. This means more than you may know, especially if your area has chronic problems with some of these very destructive diseases. Heirlooms possess some of these resistances, as well, but they’re less well documented, so may not always appear in the catalogs or on tags. You’ll have to do a bit of research to find any disease resistance information on your favorite heirloom varieties.


Resistance To

Plants with Known Resistance



Beans, Cucumber

(AB) or (EB)

Alternaria Blight / Early Blight

Carrot, Tomato


Angular Leaf Spot


(AS) or (A) or (ASC)

Alternaria Stem Canker



Bacterial Wilt



Bacterial Blight

Beans, Carrot


Bacterial Brown Spot


(BLS 1-3)

Bacterial Leaf Spot Races 1-3


(BLS 1,2)

Bacterial Leaf Spot Races 1 & 2


(BLS 1-10)

Bacterial Leaf Spot Races 1-10



Bean Mosaic Virus



Black Rot



Cercospora Blight



Cucumber Mosaic Virus

Cucumber, Summer Squash


Club Root

Chinese Cabbage


Cavity Spot



Curly Top Beet Mosaic Virus



Cladosporium Leaf Spot



Cucumber Vein Yellow Virus



Downy Mildew

Beans, Cucumber, Broccoli, Cabbage, Chinese Cabbage, Lettuce, Melon, Spinach

(F) or (F1)

Fusarium Wilt (Race 1)

Melon, Peas, Tomato

(F2) or (FF)

Fusarium Wilt (Races 1 & 2)

Melon, Peas


Fusarium Wilt (Races 0, 1 & 2)



Fusarium Basal Rot



Fusarium Crown and Root Rot



Fusarium Yellows

Cabbage, Chinese Cabbage


Halo Blight


(L) or (St)

Gray Leaf Spot



Late Blight



Leaf Mold



Lettuce Mosaic Virus



Maize Dwarf Mosaic Virus






Northern Corn Leaf Blight



Lettuce Aphid



Pea Enation Mosaic Virus



Phytophthora Root Rot



Pepper Mottle Virus



Corky Root Rot



Pea Leaf Roll Virus



Powdery Mildew

Beans, Cucumber, Carrot, Melon, Peas, Pumpkin, Summer Squash, Tomato


Pink Root



Papaya Ringspot Virus

Cucumber, Summer Squash


Bacterial Speck



Potato VIrus Y



Common Rust

Asparagus, Beans, Corn


Corky Root






Southern Corn Leaf Blight






Stewart’s Wilt



Tomato Bushy Stunt Virus



Tomato Etch Virus


(TMV) or (T)

Tobacco Mosaic Virus

Pepper, Tomato


Tomato Mosaic Virus



Target Spot


(TSWV) or (SWV)

Tomato Spotted Wilt Virus

Pepper, Tomato


Tomato Yellow Leaf Curl Virus



Verticillium Wilt



Watermelon Mosaic Virus

Cucumber, Melon, Pumpkin, Summer Squash


Zucchini Yellow Mosaic Virus

Cucumber, Summer Squash

Learn all about seeds in GREENHOUSE SEEDS GUIDE: How to start seeds in your greenhouse>>

Kristi Waterworth
image: Advait Supnekar via Compfight cc
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