There are a couple of reasons why it can become necessary to repot your rosemary. The most common reason is that it becomes root bound, but it can also be for other reasons which I will explain in this article. If this happens, you have to act as soon as possible, but how can you know?
The best way to know if a rosemary plant needs to be repotted is to check the roots. If they fill up the entire pot, the plant needs to be repotted. Other signs include stunted growth, wilting, leaves turning yellow and brown, and soil drying out faster than it used to.
It can be stressful for the plant to be lifted out of its pot, so be as gentle as possible if you do it. Before you do that, though, I recommend that you look for some of the other signs I mentioned. I cover these and a few more in more detail below.
Does My Rosemary Need to Be Repotted? How to Know for Sure
The clearest sign rosemary needs to be repotted is that its roots fill up the entire pot. When that happens, they are unable to obtain water and nutrients as efficiently as they should and the plant must be repotted. Repotting can also be necessary to save rosemary that has become overwatered.
When a plant’s roots fill up the entire pot, the plant has become root bound, which essentially means that the roots have run out of room and are bound by some barrier, typically the walls of a pot or container. When lifted out of its pot, it looks similar to my rosemary plant in the photo above.
If you can already tell that your rosemary is root bound based on this, there is no need to read the rest of this article. Instead, head over to my other article where I explain how to repot your rosemary.
Overwatered rosemary can also sometimes be saved by repotting it into a larger pot with new, dry soil that can soak up some of the water. I get more into this later in this article.
It can be beneficial to repot rosemary once in a while to reduce the risk of these problems. Many people recommend doing it every year, and while that is a good way to do it, it doesn’t necessarily have to be that often. I have another article where I go into more detail about how often you should repot your rosemary.
As I mentioned earlier, it can be stressful for rosemary to be lifted out of its pot like I did in the photo above, so if you don’t have a strong suspicion that yours is root bound, I recommend that you look for some of the other signs first. Here is a list of signs to look for.
Sign #1: Roots Coming Out of the Drainage Hole
I usually look for this before I look for any other signs when I suspect any of my plants, rosemary or otherwise, might be root bound.
If roots are coming out of the drainage hole, it means that the pot is, at the very least, not tall enough and that the plant should be repotted.
If you see this, there is no need to look for other signs. Your plant either needs a larger pot or you need to prune the roots by cutting off the bottom third with a saw or a serrated knife.
Go with a pot that is at least 1-2 inches (2.5-5 cm) taller and wider. I like to use terra cotta pots as the material allows moisture to escape through the sides in addition to through a drainage hole, which creates a better soil environment.
Sign #2: Stunted Growth
There are many reasons why rosemary can grow slower or even stop entirely and not all of them are negative. A very common reason for stunted growth in potted rosemary, though, is that the plant has become root bound.
When rosemary becomes root bound, it needs to be repotted as soon as possible since the roots can no longer obtain water and critical nutrients as efficiently as needed. If this isn’t solved, the plant will eventually die.
If your rosemary has stopped growing, I recommend that you carefully lift it out of its pot to see if the roots take up all the room. If they do, repot your plant into a larger pot as soon as possible.
Sign #3: Wilting
As I explained above, root bound rosemary cannot obtain water and nutrients as efficiently as needed and when that happens, the plant will begin to wilt.
Just keep in mind that wilting can happen for many reasons and while being root bound is a common reason, so is overwatering and underwatering.
Sign #4: Foliage Turning Yellow or Brown and Dry
Like several of the other signs I cover in this article, this one can also happen as a result of the plant being root bound.
Leaves can turn yellow and brown and become dry if the plant can’t obtain the water and nutrients it needs to support the foliage properly. If this happens because the plant is root bound, it should be repotted.
Keep in mind that the foliage can also turn yellow or brown and dry for other reasons including overwatering, underwatering, and fertilizer shock, so let’s get into the only certain way to tell if your rosemary is root bound.
Sign #5: Roots Fill up the Entire Pot
If you have looked for the signs I have mentioned until now and you suspect that your rosemary is root bound, I recommend that you carefully lift it partly out of its pot so you can get a look at the roots.
Be very gentle when you do this as the plant doesn’t exactly love it. It does love growing in a sufficiently large pot, however, so it is absolutely worth doing so you can know for sure if you need to repot it.
I have made a mess while doing this plenty of times to know that it is best to do outside or to lay out some newspapers or similar. I highly recommend that you do this to avoid making a mess.
Sign #6: Soil Dries Out Quicker Than It Used To
If there isn’t enough soil in the pot to soak up all the water the plant needs, it will dry out faster and your rosemary will need to be watered more frequently. This also happens if the roots have grown so large that they take up a lot of room in the pot.
This is a clear sign that the plant needs to be repotted since it (and especially the roots) doesn’t have the room needed to thrive.
Your plant might not be root bound yet but chances are it is on the way so I recommend repotting it sooner rather than later to avoid potential problems.
Sign #7: Soil Does Not Become Fully Dry
It might seem a bit counterintuitive after reading the point above but soil not drying out can actually also be a sign that you need to repot your rosemary but for a different reason.
If the top of the soil doesn’t dry out properly even after a couple of days of watering your rosemary, there is a very high chance that it is overwatered. The reason why the soil doesn’t dry out fully is that it is saturated with water and the plant and its roots are struggling to keep up.
I usually do a couple of things when this happens. Firstly, I make sure to water the plant less to give it a chance to catch up with the excess water that is already in its pot. Secondly, I see if I can find a sunnier spot for it to help it absorb the water faster.
If the problem is critical, the best thing you can do is often to repot the plant into a larger pot with fresh, dry soil that can soak up some of the excess water, making the soil less saturated overall.
If you repot overwatered rosemary, do not remove much of the old soil as it can stress the roots. Instead, let the new soil soak up the excess water, and don’t water it additionally until the top few inches of the soil becomes dry.