What are Woody Herbs and Why are They Special?

Here’s a thinker for today’s topic: imagine the world where thyme, sage, oregano, and rosemary aren’t considered herbs!

Well, you might be surprised…

Spearmint

eyy rosemary lol guess what I just found out

Spearmint

you an ur besties thyme and lavender aint herbs

Rosemary

Sigh. What article did you read this time around?

Spearmint

eyy its not me its science check this wikipedia definition out

guess yall are just shrubs lol

Thyme

It’s a technical thing.
Some think you a weed because you can’t keep your roots to yourself.
Stop bothering us with trash, mintboy.

We use our woody herbs like all other herbs (like, uh… adding spices to food?) and we have been calling them “herbs” all this time. So, how come?

Thing is, one of the existing definitions for an herb is that it’s herbaceous. If you read the Wikipedia excerpt above you already know where this is going. All of the green growth (flowers, buds, stems, leaves) of herbaceous plants dies prior to winter; they let nothing remain above the ground for the off-season.

However, provided it’s a perennial (and your climate won’t kill it over winter), it will leave behind a living root system. Come spring, the plant will start re-growing itself and later you will be able to harvest it once again.

Mints, catnip, lemon balm, tarragon… all of these are our familiar herbaceous perennials. They tend to spread around your yard using their root system, too! All the cool underground action we don’t get to see. Per botanical classification these guys are the herb-herbs.

Now, what about perennials that grow some spine? Many woody-stemmed perennial herbs are pretty much miniature shrubs — thyme, winter savory, sage, lavender, oregano, savory, rosemary, and many others. They leave behind their “trunks and branches” over winter as they sit dormant.

Sounds familiar? Well, this behavior is why woody herbs are grouped with trees and shrubs proper! If you think about it, we call bay leaf an herb, but it comes from a tree, laurus nobilis.¹

Rosemary

Honestly, I think Spearmint is just jealous.

Of course, the botanical classification is a little too technical for how we actually use herbs. Most gardeners use the term “herb” for many plants they use as ingredients for cooking, medicine, aroma, household, and decoration. Leaves, roots, stems, flowers, or even fruit — anything goes!²

Dill

What you guys call “dill seed” is actually dill fruit.
Only straight facts here, fam.
#schizocarp_fruit

“Neat,” you may be thinking, “but is all of this useful to know, or…?”

Give Our Woody-Stemmed Herbs Some Love!

Pruning Woody Herbs

Here’s an important one: remember that, just like you would with any woody shrubs, you only want to prune down to green leaves and not all the way to the bare wood to make sure your herb can re-grow.³

The green part of your plant is where young growth happens. Young green turns to mature brown, the wood, which is more of a support system for your plant. It’s much harder for your plant to re-grow itself from old parts of its body!

(For you super-geeky gardeners out there, this is the difference between primary and secondary growth: greens and roots grow long, while woody parts get thick.⁴ ).

Thyme

I may look fragile, but I like it when you are rough…

Thyme

Oh, crap! Wrong number, wrong number!
I am so sorry!

Don’t skip on pruning! Start early: manicuring your established herbs in late spring will help prevent disease during summer. Give special attention to the stems closest to the ground. Get rid of dead foliage and extremely low branches at the plant’s base, if there are any. Air circulation is very important!

Beware: you might end up pruning some of these guys every month! With healthy herbs comes great harvest… oh, and great responsibility, too. Encourage yourself to keep cutting by finding some spicy recipes to experiment with!

Then, during summer, trim the branches by one-third to one-half their length. If you are taking them indoors over winter, cut even more. Outdoors, stop pruning about a month before the first frost so that very young growth doesn’t get hit hard with that sharp temperature drop.⁷

Harvesting Woody Herbs

All of the pruning rules apply! (In fact, we tend to group the two together because pruning is often harvesting!) When you are ready to harvest, cut two-thirds of what grew this season, but not all the way up to the woody parts.

When to harvest? For woody-stemmed perennials the best time is mid-blossom, when the oil production is at its highest. It won’t work with all of your other herbs — many might develop an unpleasant taste when flowers show up. Woodies are a little special this way.

Try your best to harvest one month before the first frost, at the latest. Gentle new growth might not have a chance to harden off if you cut your herb too late in the season.

If you are going to be drying your herb, harvesting it when it’s still wet will only cause problems to the process. (We discuss more intricacies behind harvesting in our guide!)

The best way to preserve both texture and flavor of your woody perennials, is to preserve them by drying them. Unlike your annual herbs with thin leaves, woody perennials won’t freeze as well.⁶

Other Woody Cravings

Woody perennials tend to like their sun and a loose soil that crumbles in your hand. Drainage is very important for these guys! You can try planting them into raised beds or mixing sand and/or gravel into their soil.

Here’s a neat mulch trick: using something light-colored like gravel, sand, marble chips, or ground oyster shells will reflect sunlight onto the plant. This also means they will dry quickly in the morning — less risk of fungal diseases and insect pests!

Vice versa, dark organic mulches (wood chips, for example) will hold water, not reflect light, and might raise the risk of fungi.

Spearmint

screw these hard-asses walkin around like they own the dam place
try propagating them
good luck gettin them to come up from seed they show bout as much progress as my brother jonathan trying to start his own business for the second year now

Spearmint

they say there is this thing called layering where you propagate these woody suckers from branches
hell nah bruh unless you be doing cuttings you be waiting for months for these suckers to form some roots
sure i may be kind of a weed sometimes but at least i am *loyal*

1. Mary H. Dyer, “Woody Perennial Information: What Makes A Perennial Woody,” Gardening Know How, last modified September 21, 2020, https://www.gardeningknowhow.com/ornamental/shrubs/shgen/woody-perennial-information.htm. [↩]
2. Kerry Smith and Wendy Ulrich, Growing Herbs (Bay Minette, AL: Alabama Cooperative Extension System, 2013), https://ssl.acesag.auburn.edu/pubs/docs/A/ANR-1164/ANR-1164-archive.pdf [↩]
3. Jessamyn Tuttle, Perennial Herbs (Pullman, WA: Washington State University, 2020), https://s3.wp.wsu.edu/uploads/sites/2073/2020/08/Perennial-Herbs.pdf [↩]
4. “Biology II Module 6: Plant Structure and Function, Plant Stem Growth,” OpenStax College, last modified January 7, 2021, https://courses.lumenlearning.com/biology2xmaster/chapter/growth/ [↩]
5. Jeanine Davis, “Harvesting and Preserving Herbs for the Home Gardener,” NC State University College of Agriculture & Life Sciences, last modified November 11, 2019, https://content.ces.ncsu.edu/harvesting-and-preserving-herbs-for-the-home-gardener [↩]
6. Susan Belsinger and Arthur O. Tucker, Grow Your Own Herbs: The 40 Best Culinary Varieties for Home Gardeners (Portland, OR: Timber Press, 2019), see “Harvesting and Preserving Your Herbs.” [↩] [↩]
7. Arthur O. Tucker and Thomas DeBaggio, The Encyclopedia of Herbs: A Comprehensive Reference to Herbs of Flavor and Fragrance (Portland: Timber Press, 2009), see chap. 8, “Keeping Herbs Healthy.” [↩]