Those catalogs are a lot more than a list of products the seed companies want to sell. They are encyclopedias of information that, among other things, tell us which plants won't grow in Colorado. That keeps us from throwing away money for plants destined to fail with our growing conditions. Catalogs also tell us about the latest plant introductions and the newest hybrids. Sometimes companies will provide tips and techniques for growing particular plants.
Some companies offer plants and seeds from another era, before the availability of modern hybrids.
By using information about mature size and height, you can draw up plans that avoid plants shading one another. You can design effects that include a mass of color or a tiered border garden. Blooming times, which are listed in catalogs, will help you choose varieties that will bloom in grand succession from early spring to the first frost of fall, or beyond. Some seed companies feel so confident about the educational value of their catalogs, they assess a small charge, and they usually are well worth the nominal cost. This gardener saves seed catalogs over the years and the collection has become a valuable reference for home gardening.