Seed Catalog Guidelines

Nov 23, 2019

By Susanne von Rosenberg, UC Master Gardener of Napa County


If you've ever bought gardening items from a catalog or website, odds are that you are starting to receive seed catalogs for 2020. Seed catalogs are awe-inspiring, kind of like a fitness magazine is for the average person.


Because seed catalogs are so enticing, it's important to read them with a bit of a critical eye. Feel free to dream and enjoy. Then, when you're ready to go from fantasizing about all the amazing things that you could grow (if only you had more time, or garden space, or maybe a different climate) to what would actually be right for you and your garden, here are some things to consider.


First, where does the seed catalog originate (and where are its trial gardens)? I've received seed catalogs from New England, New Mexico, the Pacific Northwest, the upper Midwest, Missouri, Central California and more. When seed companies describe how their varieties perform, not only are they giving you information that reflects optimal growing conditions for that variety, they are also reflecting the results that they see in their trial gardens. Which seed company is most likely to have seeds that will do well in my Napa garden, and whose description of the plants' performance will come closest to what I can expect?


Second, does the catalog give you all the information you need to make a good decision? Many catalogs skimp on important information. They are doing a terrific job painting a picture for your imagination, but you need more than a lovely vision to make a good decision for your garden.


At minimum, for plants you are already familiar with, you need to know the days to maturity (or flowering period), the mature size of the plant, its disease resistance, and whether that particular variety was developed for a specific climate.


Many of us regularly grow tomatoes and understand the conditions they prefer. But when we decide to grow a new variety, it's important to know whether it takes 60 or 90 days to mature from transplant; whether it is a determinate variety that will stop growing at four feet or less, or an indeterminate type that will keep growing; and, of course the size of the full-grown tomato. It's also helpful to know if this new variety is resistant to soil-borne diseases like verticillium wilt and fusarium wilt.


But it's equally important to know if that particular tomato was developed for a specific climate, such as foggy San Francisco or hot and humid Florida. The less you know about a specific variety or type of plant, the more information you need to make the right decision.


A good seed catalog will tell you the plant family or provide the scientific name. The catalog description should also indicate whether the seed is hybrid, open-pollinated or organic; the minimum number of seeds in the packet; the typical planting dates for various parts of the country; frost tolerance; sun or shade requirements; how thirsty that plant is; and whether it has any special needs.


Some seed companies certify that all of their seeds are GMO-free. If the seed catalog doesn't provide enough information, you'll need to do some research to fill in the blanks.


Note what the seed catalog fails to mention. If the description goes on and on about the appearance but is silent about the productivity or taste, you may have a plant that has superb or unusual color but produces only a few of the desired flowers or vegetables. Or it could be tasteless or finicky about growing conditions.


What a catalog description doesn't say can be revealing about a variety's weaknesses. Taste is subjective, and my idea of a tasty tomato may be different from yours, so look for a detailed description. It can be quite entertaining to figure out what is not being said.


Finally, be aware that the plant described in the catalog was probably grown under optimal conditions. For vegetables, that means that your days-to-harvest will almost always be longer, and you may not get the same yield. For ornamental plants, it may mean later flowering or less-showy blooms than you see in the catalog. Be skeptical about that ubiquitous term “up to,” as in “up to six feet tall” or “up to two feet long.” Again, that's under optimal growing conditions. While it's possible you'll grow a 2-pound tomato or a 16-foot-tall sunflower, it's likely that most of your tomatoes will be smaller and that your sunflowers will be too.


So, enjoy your seed catalogs and your dreams of lush plants-to-be. Then bring on your inner investigator when it comes time to actually choose seeds.


The UC Master Gardeners of Napa County are volunteers who provide UC research-based information on home gardening and answer your questions. To find out more about upcoming programs or to ask a garden question, visit the Master Gardener website ( or call (707) 253-4221 between 9 a.m. and noon on Mondays, Wednesdays or Fridays.