Rosemary becomes root bound very easily, which means you might have to repot it quite often, but how often exactly?
Generally speaking, rosemary should be repotted every year into a pot that is 1-2 inches (2.5-5 cm) wider and deeper. Using a larger pot, however, can provide the plant with sufficient room to be repotted less often. Regardless of the pot used, rosemary should always be repotted before becoming root bound.
How often a plant needs to be repotted depends on a handful of factors that are unique to your specific situation. So while once per year is a good rule of thumb, it is impossible for me to say precisely how often your specific rosemary should be repotted. I do, however, have a handful of tricks you can use to figure it out.
These Factors Determine How Often Repotting Is Needed
How often a plant needs to be repotted depends on a handful of factors of which some are within your control and some are not.
The primary factors that determine how often repotting is needed are:
- The size of the pot or container
- The amount of direct sunlight the plant receives
- The temperature
- Type of soil
Of course, the primary factor is the size of the pot. If the pot you use is small, your plant, and more specifically its roots, will outgrow it much faster than if you use a larger pot.
It is generally a good idea to repot rosemary into a pot that is one size, or 1-2 inches (2.5-5 cm) wider and deeper every year. If you use a larger pot, though, it can stay for longer before you need to repot it. I have sometimes bought a small rosemary and transplanted it into a 12-inch (30 cm) pot right away and it worked just fine for several years.
Generally speaking, the more sunlight a plant receives, the faster it grows. That also goes for the roots, so if your plant is growing in a very sunny spot, it will outgrow its pot faster than if it got less sunlight.
Rosemary should ideally get 8 hours or more direct sunlight per day on average but it can survive with as little as six.
The temperature also plays a significant role in how often repotting is needed. That’s because rosemary grows faster in warmer temperatures. In fact, most plants do.
Lastly, the soil type also affects how fast plants grow. Rosemary grows best in soil with little organic material and a lot of sand to improve drainage. Soil that is too rich in nutrients will cause the plant and its roots to become damaged, leading to stunted growth.
How to Tell With Certainty That Rosemary Should Be Repotted
While there are a handful of signs to look out for, there is one in particular that tells you that your rosemary needs to be repotted as soon as possible.
Rosemary that has become root bound needs to be repotted immediately to limit the damage to the roots. Plants that are severely root bound can die since they are unable to obtain the water and nutrients required to sustain them.
If your rosemary is root bound and needs to be repotted, I have another article where I cover how to repot rosemary, so check it out.
Rosemary absolutely hates being root bound, so it is important that you know how to tell if it is. To do that, carefully lift the plant out of its pot and take a look at the soil. If you don’t see many roots, your plant is fine but if it looks like mine in the photo below, it needs to be repotted as soon as possible.
I go into more detail about why rosemary hates being root bound in another article where I also share two simple solutions to the problem.
While taking a look at the plant’s root system is the easiest way to tell if it needs to be repotted, it can be stressful for the plant. Especially if you do it too often.
Here are some other signs your rosemary is root bound and needs to be repotted.
- Stunted growth
- Roots coming out of the drainage hole
- Wilting
- Soil dries out quicker than it used to
I have another article where I go into more detail about signs that indicate your rosemary needs to be repotted.
While the plant being root bound is by far the most common reason why repotting becomes necessary, it is not the only reason. For example, an overwatered rosemary can often be saved by repotting it into a larger pot with new, dry soil.
What You Risk by Not Repotting Rosemary Often Enough
I understand if repotting seems a bit overwhelming if you have never done it before but if you have, you know that it is not that complicated. Still, you might not want to do it and that is fair, but you should be aware of the consequences.
If potted rosemary is never repotted it is likely to become root bound. When that happens, it is unable to obtain the water and nutrients it needs, which leads to stunted growth at first and kills the plant after a while.
So, of course, I recommend that you repot it as often as it is needed. I go into more detail about why repotting rosemary is important here.
If you want to do it as infrequently as possible, just transplant it into a 12-inch (30 cm) or larger pot from the beginning. That will last for several years.
Another risk you run by not repotting your rosemary is that the soil becomes depleted of any nutrients the plant needs to continue growing. Sure, you can give it a small amount of fertilizer once in a while, but in my experience, it works much better to replenish the soil by putting the plant in a larger pot that you fill with new soil.
I have also experienced mold developing on parts of a pot I kept a rosemary in for a long time. I had to repot my plant into another pot before the mold got to it to save it and then clean the old pot thoroughly afterwards.