When I started my private herb garden a while back I watched in excitement as the plants grew stronger and more voluptuous every day. But soon, flower buds started to form at the top of some stalks. I was happy they were thriving but then I wondered: should you let herbs flower?
If you are planning on using herbs for cooking, letting them flower is not a good idea. Once herbs have flowered they will have less flavor and taste more coarse. It is best to cut herbs just before they begin to flower.
In this post, I’ll go over the dos and donts of herb flowering. To start off we’ll have a brief look at why herbs actually flower. This will help us get a better understanding of the role the flower top plays. I’ll also talk about some specific examples such as basil, thyme, and rosemary and show you how to keep your herbs from flowering in the first place!
Why you should not let herbs flower
You should not let herbs flower primarily because their leaves loose flavor and potency. This is because all the energy that went into producing fresh healthy leaves before now is used to create a flower bud and seeds.
Herbs that have flowered will have a much milder and blander taste than non-flowering herbs. Flowering herbs are still edible but your basil, thyme, or rosemary will just be less savory and might tatse a little coarse.
Generally, herbs taste best just before they flower. This is when the leave production has reached its peak and thus is the most flavorful it will ever be.
If you take another look at the life cycle of herbs you will easily find the reason for the loss of flavor. When the first begins its life from seed all the potential energy stored inside the side is used to develop its roots.
The roots give the herb more energy by extracting nutrients from the soil and water. This additional energy can soon be used to grow voluminous leaves. The bigger the leaves the more surface area the herb has to perform photosynthesis.
Photosynthesis takes carbon dioxide (CO2) from the atmosphere and water (H2O) from the soil and converts these into oxygen (O2) and Glucose. Once the herb has produced enough glucose and grown its leaves for maximum efficiency it will inevitably enter its last stage of life by developing flowers.
Not that we know why herbs flower and why letting herbs flower will reduce its use and taste in cooking, let’s see how we can prevent this.
Why herbs flower
Herbs essentially flower because they are genetically programmed to do so. In fact, all plants flower for the exact same reason. To produce offspring and continue the cycle of evolution. The flowers that herbs grow produce seeds and can attract small insects which can carry the seeds farther distances.
This way the herb is more likely to spread its genetic material and have a higher chance of regrowing the following season. Bland as it may seem to us, a herb’s highest purpose is to grow flowers and distribute its seeds. Once that job is done, it can die happily.
The timelines above illustrate the different life cycles of perennial, biennial, and annual herbs. Perennial herbs will typically flower in August and September and sow their seeds soon after. Biennials flower and sow their seeds only once every two years in July and August. Annual herbs go through the same process in early or late summer.
Now that we’ve understood the biological meaning of a flowering herb let’s look at why it may not be a good idea to let this process occur in our domesticated herbs.
How to keep herbs from flowering
Keeping herbs from flowering will make sure your herbs always taste fresh and potent. By preventing the herb from flowering all of the plant’s energy will go into growing delicious leaves.
Here are three way to keep your herbs from flowering:
- Check the flowering schedule: Since herbs flower, at different times during the year, it can be difficult keeping track of each cycle. Make sure you know which of your herbs are perennials, biennials, and annuals. Then follow the timeline above and note the flowering date of each herb.
- Trimming: A simple but effective way of keeping herbs from ever growing flowers is to trim their stalks before they become strong enough to grow flower buds. Knowing their flowering schedule can help identify growing buds early on. Cut the stalks just a few inches below the top and the herb will regrow its stalk and leaves before flowering.
- Indoor Herb Gardening: To prevent herbs from flowering it can be effective to keep them indoors. When the plants are not exposed to the natural changes in atmosphere and climate they might delay flowering or not grow flowers at all.
Of course, sometimes we might overlook a growing flower bud or two. Or perhaps you went on a beautiful 4-week holiday only to come back and find your herbs all blooming. So, what do when herbs already have started flowering?
What to do when herbs start flowering
If flower tops have already formed on your herbs: don’t despair! It is still completely fine to eat herbs that have flowered or even eat the flowers themselves in some cases. Let’s look at three common herbs and how to handle their flowering:
- Thyme: With thyme, it’s always best to simply cut stalks as you need them. Even letting thyme flower is not does not necessarily degrade its flavor too much. In fact, you can actually eat the flower tops and add them to your dish just as you would thyme leaves.
- Rosemary: Rosemary will grow purple and small flower buds if you let it. It is especially important to clip off any dead or dried-up flower heads on your rosemary as they continue to consume the herb’s energy resources. Fresh rosemary flowers have a delicate and milder taste than its potent leaves.
- Basil: If you are planning on keeping your basil plant around for longer it is especially important to keep it from flowering as the herb may die soon after. Once flower buds have already formed cut them immediately. Basil flowers are also edible, have a milder taste and can even be used in tea!
Conclusion
Letting herbs flower is not a good idea if you plan on using them in your cooking. But letting them flower for the sheer joy of it is never wrong either! Just remember that the herb is going through its natural life stages from seed to roots to leaves to flower and back to seed.
Simply keep gardening shears close by when growing herbs and cut a few inches beneath the growing buds every now and then. This will be enough to keep your herbs fresh and strong for a long time!
“Willow Herb Flowers, Epilobium ciliatum” by stonebird is licensed under CC BY-NC-SA 2.0
On this site, I share thoughts and ideas about gardening and botany while constantly learning to become a better botanist myself!
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