Choosing soil for rosemary has never been the easiest thing for gardeners to manage. Sadly, tons of rosemary plants have been sacrificed in the process.
I’ve heard many troubling stories about rosemary. People have killed their rosemary by planting it in the wrong soil.
Yes, rosemary is notorious for being delicate with its soil needs. But actually, it’s not very hard to find the mix that best suits this wonderful herb.
Below, you’ll find all the information I can give you to help you choose the ideal soil for your rosemary growing.
We hope through reading this, you’ll see it’s easier than you think. It’s a matter of understanding how this versatile herb grows in and reacts to its environment.
Let’s get started!
In a hurry? My favorite soil mix is 1/2 Fox Farm potting soil mixed with 1/2 perlite for better drainage. It's all-natural and has all the nutrients your rosemary plant needs to grow and thrive.
Understanding Your Rosemary Soil Needs
I once heard an experienced gardener say that “rosemary only grows when you don’t care about it.”
Of course, no plant grows well without the proper attention. But it does say something about the soil needs of rosemary.
Rosemary doesn’t like your overflowing attention, especially when it comes to watering. Once you know this, you can see that this herb loves well-drained soil.
Rosemary can die in over-moistened soil. That’s understandable, given that it originated in the dry sun of the Mediterranean.
Rosemary grows best when the soil surrounding its roots can trap a minimal amount of water. The air must circulate smoothly underground, as well.
Gardeners growing rosemary outdoors will leave the plant without water for an extended period. They’re hoping not to suffocate the roots.
In general, rosemary does perfectly fine in gardens, but the soil there isn’t always the best.
That’s because outdoor gardens tend to have a very deep structure. They are constantly exposed to the air, so water is never really trapped.
But rosemary plants grown in containers or pots are a different story.
You cannot use the same garden soil in a pot with your rosemary and expect it to survive.
When growing rosemary in pots, you must first look closely after the soil drainage.
You must also focus on how “rich” the potting soil is. Your rosemary can grow very slowly. This happens when the growing mix is devoid of the essential nutrients.
Here is one important thing you must know about rosemary. It’s pretty flexible regarding the acidity of the soil it resides in.
It’s a little-known fact that rosemary can thrive in soil with a pH of anywhere between six and eight.
In this next section, I outline two great combinations or mixes. These can work as a suitable potting soil for your rosemary.
The Ideal Soil for Rosemary:
The Standard Mix: 2/3 Regular Potting Soil + 1/3 Perlite
The simplest mix you can use is an adjusted regular potting soil. That is one of the most popular mixes for rosemary used by gardeners.
Any high-quality potting soil is well-drained. But it is not enough for it to help grow drought-tolerant plants.
Growing rosemary in unmodified potting soil has mixed outcomes. Most gardeners cannot keep the herb alive using regular potting soil alone. Others have managed to have their rosemary thrive in such a soil.
Regular potting soil tends to be inadequate on its own when it comes to keeping rosemary alive. Gardeners prefer adding perlite to it.
The hidden magic of perlite is its ability to flush excess water out. It does this without being hydrophobic. A hydrophobic material does not let water enter in the first place. Water prevention is something you do not want for your rosemary.
Mixing one part perlite with two parts potting soil creates the standard mix. You can use this mix to grow your rosemary.
I highly recommend using the famous Foxfarm Potting Soil.
The drawback of this mix:
One major drawback depends on many factors, aside from the soil itself. This mix can sometimes fail to deliver the ideal drainage for rosemary.
Even so, it is possible to overcome such an issue. You can add more perlite or reduce the number of times you water your rosemary.
An Alternative Mix For Stronger Drainage: ½ Cactus Soil + ½ Perlite:
Now, this may seem a bit unconventional to those just starting. Experienced gardeners often use cactus soil, or the “cactus and succulent mix,” to cultivate various herbs. Rosemary, sage, and thyme are prime examples.
They make cactus soil mainly for cultivating cacti and succulent plants in pots, such as aloe vera.
For that reason, gardeners know such a mix is excellent for draining water.
Nevertheless, gardeners still prefer to add perlite to this mix. It’s less harsh on their rosemary.
Perlite works to keep the roots well-aerated. And its water-draining capacity is moderate compared to the cactus soil.
If you do use this mix with your rosemary, you’ll never need to worry about water drainage. That is unless the soil becomes too old while in the pot.
Of course, you should always choose the best brand of cactus soil you can.
I usually use Hoffman’s Organic Cactus and Succulent Soil Mix. This mix has always satisfied me enough to recommend it to others.
The drawback of this mix:
The main problem with this mix is that it may not be as rich in nutrients as high-quality potting soil.
Organic products that enrich the soil have water-trapping properties. That’s why they’re not added in bulk to the “cactus and succulent” mix.
Another issue you may face is the soil might dry too fast, or at least faster than what your rosemary can keep up with.
In this event, you should add vermiculite or another water-trapping material to the soil.
Important Things That You Should Know
The Use of Fertilisers
In your gardening journey, you will naturally always need the help of fertilizers to grow your herbs. This, of course, includes our queen, rosemary.
I would say that rosemary needs little to moderate amounts of fertilizers to grow well.
An evergreen herb, such as this, has all year to grow and is thus not a huge nutrient consumer.
At the same time, we regard almost all fertilizers as water-retaining. Unfortunately, they could have a negative impact on the drainage capacity of your soil. This would be true if you were to add them in huge quantities.
If you are using Foxfarm—or any other nutrient-rich potting soil—forget about altering the soil with fertilizers. Wait at least the first two or three months.
Afterward, or in other situations, you must use natural fertilizers to feed your herb. In my experience, the best choice is a mix of vermicompost and other natural soil amendments.
Vermicompost is also known as “worm castings.” It is a natural fertilizer containing high nitrogen levels. Nitrogen is one of the most essential nutrients for proper plant growth.
The best worm castings on the internet are, without any doubt, Wiggle Worm Soil Builder Worm Castings.
Remember, you must use soil amendments in moderation. Even then, don’t add more than one part of any fertilizer with two parts of your soil or mix.
The Drainage of Your Pot
Those who fail to grow rosemary can sometimes assume the soil has a problem. Instead, the problem could be with the pot.
Pots lacking width and the proper draining holes can spell a big problem for your rosemary.
These kinds of pots usually trap water in a viscous way that immediately kills the herb.
I recommend you always go for the highest quality of pots. You can also choose containers that are well-designed for draining water.
Don’t Forget to Repot
Repotting means changing the soil your herb is growing in.
This is an especially important activity to which you should pay close attention.
Every type of soil will change after the plant uses it for a finite time—usually months.
The change mainly affects the texture and nutrient composition of your soil. It will start to become less porous and empty of nutrients.
At that point, changing the soil is a must, or else your rosemary’s health—and growth—will continue to decline.
Make changing your herb pot’s soil a routine every few months.
So, that’s all you need to know! You can now go forth and grow your rosemary. Don’t forget to share your thoughts and experiences in the comments below!