I have marjoram and/or oregano growing all over. I like it and use it
as filler, left over from herbs I bought several years ago. But, to
cut them and use for seasoning, I don’t know which is which and they
don’t seem to be so fragrant. Should I just start over and buy new
plants to know what I have? How can I tell the difference between the two plants?
Everytime I get this question (this almost qualifies for a frequently asked
question) I have to look it up again because even the authorities get mixed
up.
Oregano and marjoram are the same genus, Origanum, but different species/hybrids. Marjoram usually refers to Origanum majorana. Marjoram leaves tend to be more gray green in color than oregano, and the leaves are generally smaller. Oregano usually refers to Origanum vulgare. It has a more pungent flavor, while marjoram is sweeter and milder. If you are interested in learning more, this guide from the Herb Society of America goes into great depth on oregano and marjoram.
The short answer to your question is yes, you should start over with new
plants if you want good flavored herbs. You could bring in a sample to the Hyde Herbarium here at the Center for Urban Horticulture, 3501 NE 41st St. Seattle.