Flowering is a natural part of rosemary’s reproductive cycle, so if your rosemary has the right growing conditions, it will flower sooner or later but if you want some tips that can help make your rosemary flower faster, for longer, and produce even more flowers, you should stick around.
How To Boost Flowering in Rosemary (6 Tips That Actually Work)
in this article, I cover six methods you can use to encourage your rosemary to flower faster, flower for longer, and produce more flowers. Here is a brief summary of the methods before I go into more detail about each of them.
- Let your plant get at least 8 hours of sunlight per day
- Allow the plant to become slightly root bound
- Prune the plant every year and harvest frequently
- Stop using nitrogen-rich fertilizers
- Use well-draining, sandy soil with little organic matter
- Water every 1-2 weeks
Before I elaborate on each of these points, I want to mention that rosemary rarely flowers in its first year in my experience, so if your plant is still young and small, the best thing you can do to make it flower might be to wait.
If you suspect there might be an underlying problem that prevents your rosemary from flowering, consider taking a look at another article I wrote specifically about reasons rosemary won’t flower.
That said, keep reading to see if any of the tricks I cover in this article can help you.
If you keep your rosemary inside and you’re wondering if it will even flower, you should know that it can but it is not quite as simple as if it grows outside. To learn more about this, check out my article about rosemary flowering indoors.
But first, here are some tricks to help promote flowering in rosemary.
1. Let Your Plant Get At Least 8 Hours of Sunlight per Day
Perhaps the most important factor when it comes to flowering in rosemary is the amount of sunlight the plant gets.
Rosemary is a Mediterranean herb that is used to and requires large amounts of direct sunlight to thrive. If it doesn’t get the sunlight it needs, not only will flowering be reduced but so will the overall health of the plant and its ability to grow and produce new foliage.
Rosemary should have at least eight hours of direct sunlight per day to thrive, although more than that can lead to increased growth and production of foliage and flowers.
If your rosemary isn’t getting eight hours of sunlight per day, consider moving it to another spot where it can be exposed to more sunlight than in its current spot.
2. Allow the Plant To Become Slightly Root Bound
Potted plants can become root bound which means that the plant’s roots run out of space.
It is generally a bad thing for rosemary (and other plants) to become root bound as it prevents the plant from obtaining the water and nutrients it needs. However, if your plant isn’t root bound to a point where it is critical, it can actually help promote flowering.
According to the University of Wisconsin-Madison Horticulture Extension, allowing rosemary to become slightly root bound promotes flowering.
Of course, this trick is only relevant if your rosemary grows in a pot or container since it won’t become root bound if it grows in the ground.
It is also important to mention that you should be careful that the problem doesn’t become too severe as it will eventually kill your rosemary. You can check the roots by carefully lifting the plant out of its pot. If it looks like mine in this photo, you should repot it as soon as possible to avoid problems. In that case, check out my guide on how to repot rosemary.
3. Prune the Plant Every Year and Harvest Frequently
Pruning and harvesting can help stimulate growth and flowering in rosemary and many other plants. A thorough annual pruning will lead to a more bushy plant with room for a lot more flowers but avoid cutting into old wood as rosemary may not grow back from older stems.
Prune your rosemary by cutting each stem back by up to a third. This will cause them to split and grow as two or more new stems from the point where you cut.
Harvesting will have the same effect when done correctly. I have seen many people harvest rosemary by just picking the leaves, hoping that they would grow back if they left the stem. While I admire this thought, it is simply incorrect.
Instead, harvest by cutting entire stems as I show in this photo. This essentially serves as a light pruning and causes the stems to split into two or more.
So in short, correct pruning and harvesting of rosemary will cause many new stems to grow, thereby leaving room for a lot more flowers than otherwise.
Correct pruning is crucial, not only for flowering but for your plant’s health and overall growth and production, so I recommend taking a look at my detailed guide on how to prune rosemary to learn the best way to do it.
4. Stop Using Nitrogen-Rich Fertilizers
Most garden fertilizers have a so-called NPK value. This value indicates the levels of nitrogen, phosphorus, and potassium the fertilizer contains.
I want to focus on Nitrogen for now because it is often recommended to use a fertilizer with a high content of nitrogen for rosemary. While it often makes sense to do so, it won’t help if your goal is to encourage flowering.
According to this article from The Baghdad Science Journal, Nitrogen fertilization is considered the main factor for increasing plant production. This is great if your goal is to make your rosemary produce as much foliage as possible.
If you want flower production, however, nitrogen-rich fertilizer is not the way to achieve it. While it can increase the production of foliage, it can happen at the expense of flowers.
5. Use Well-Draining, Sandy Soil With Little Organic Matter
One of my favorite things about rosemary is how well it can grow in locations that are too rough for many other plants.
Unlike many other popular garden plants, rosemary doesn’t need nutrient-rich soil to thrive. In fact, rosemary grows best in well-draining, sandy soil with little organic matter.
Soil that is too rich in nutrients can result in several problems such as damage to the roots or fertilizer burn. This can stress the plant and negatively impact flowering.
Rosemary roots are prone to damage from overwatering, so sand is important in the soil as it provides the much-needed drainage for the roots to grow well.
In this photo, you can (sort of) see how dry and sandy the soil is but as you can also see, the plant is thriving and producing plenty of new foliage.
6. Water Every 1-2 Weeks
Rosemary doesn’t need nearly as much water as many other popular garden plants. Low maintenance is great but it also makes it easy to overwater if you aren’t used to it.
Both overwatering and underwatering can stress the plant and cause damage to the roots, which impacts its ability to grow and produce foliage and flowers.
While rosemary is relatively drought-tolerant, it still needs regular watering unless it rains. Allow the soil to almost dry out between waterings, but don’t let it become completely dry as that can reduce flowering.
In my experience, watering every 1-2 weeks is usually sufficient, however, you should consider the growing conditions.
If your rosemary is growing in a warm location, you might have to water it more often than once per week and if it rains frequently, you might never have to water it.
The key to correct watering is to almost let the soil dry out.
Learn more about flowering rosemary
If you are curious about the flowering process in rosemary, I recommend taking a look at my complete guide to rosemary flowering where I cover everything about the topic including what you should do when your rosemary is flowering, what happens to the plant, how to deal with flowering-related problems, and more.