Best Potting Soil for Herbs (With Examples)

Have you ever planted up all your herbs in a generic potting mix for them only to turn yellow, droopy, or die back? This has happened to almost every herbs grower in the beginning (including me when I first started!)

I have grown herbs for years and I even work in a commercial garden nursery growing herbs for wholesale to garden ceneeters so I have had lots of experience potting up herbs and even conducted a few experiments myself to determine the best soil for different types of herbs.

In this article, I share with you all the tips and secrets I learned first, as well as the tips I’ve been taught from some specialty growers, to ensure your herbs thrive with the right soil.

The bottom line is…

The best potting soil for woody Mediterranean herbs is a mix of 1/3 sand or grit to 2/3 compost for optimal levels of drainage, fertility, and soil structure to ensure flavorful herbs. Non-woody herbs such as basil and cilantro prefer multipurpose or garden compost without sand for more soil moisture.

I cannot emphasize to you enough the distinction between woody herbs that originate in the Mediterranean region of Europe and non-woody herbs with green stems is important when it comes to choosing the right potting soil for your herbs.

Mediterranean herbs require sharp drainage and less moisture around the roots due to their adaptations to dryer climates and can support themselves with their woody structure.

Non-woody herbs rely on pressure caused by a vacuum caused by water loss from the leaves (transpiration), which draws moisture in the potting soil up through the roots, maintaining their leafy green non-woody structure.

I created a table to help clarify this for you…

Keep reading for how to create the optimal potting soil for herbs and which soil amendments you should avoid to ensure the best flavor when planting herbs in pots…

Best Soil for Mediterranean Herbs

A lot of the most popular herbs valued for both their aroma and culinary flavor originate from the Mediterranean region of Europe in countries such as Spain, Italy, and Greece, where they grow abundantly in the wild and are grown as commercial crops.

Therefore to grow flavorful Mediterranean herbs we need to recreate the soil conditions of their native environment by amending your potting soil so that it resembles Mediterranean soil with gritty well-draining sandy soil, that is relatively low in nutrients and does not hold onto moisture.

The following herbs all originate in the Mediterranean region and all require the same potting soil mix:

• Lavender
• Sage
• Thyme
• Rosemary
• Oregano

The best potting soil for our Mediterranean herbs is composed of 70% peat-free, multi-purpose compost, and 30% horticultural sand and grit. A compost and grit potting soil emulates Mediterranean herb’s native soils with good drainage, medium fertility, and an aerated soil structure.

A sandy or gritty potting soil mimics the herb’s preferred sandy soils which is crucial to avoid root rot and to ensure your herbs have the best taste and aroma.

Sand and grit provide essential drainage qualities and do not contribute many nutrients to the soil or hold moisture, which helps increase the intensity of the aroma and flavor of your herbs.

Watch this video to learn how easy it is to create the optimal soil mix for Mediterranean herbs (such as lavender)…

Mediterranean herbs are specifically adapted to lower fertility soils, so if they are planted in nutrient-rich compost with added fertilizer, their distinctive aroma and flavor are not as strong and can be more vulnerable to pests and disease.

I was taught by specialist growers that excess nitrogen from nutrient-rich soil promotes excess foliage and decreases the concentration of essential oils in the leaves which are responsible for the herb’s aroma and flavor, and prevents the herbs from flowering.

From personal experience, I have found that Mediterranean herbs do not taste as strong in rich soil. Therefore, it is better to replicate their natural growing conditions with lower-fertility potting soil and good drainage so you can enjoy the distinctive fragrance and taste of your herbs when cooking.

(Read my article on choosing the best pots and containers for lavender).

Avoid These Potting Soils When Growing Mediterranean Herbs

• Any soil mix containing manure (too much nitrogen).
• Commercial soil mixtures that contain wetting agents to retain moisture or added nutrients.
• Unamended soil with no inorganic material (sand, grit, or perlite).
• Ericaceous compost.

We need to remember that our Mediterranean herbs prefer lower-nutrient soils that drain very quickly and do not hold onto moisture.

If the potting soil has a high level of nitrogen, then your herbs grow floppy and droop over and are far more vulnerable to fungal disease. So always opt for multipurpose compost rather than manure or compost with added nutrients for your herbs. These are characteristically high in nitrogen, which reduces the herbs’ flavor.

All of our Mediterranean herbs enjoy potting soil with good drainage, as they have specifically adapted to coping in climates with less available moisture with thinner needle like leaves that limit transpiration (water loss) from the leaves.

This ability to thrive in more arid climates leaves the plant more susceptible to root if it is in potting soil that stays damp for a long time, which is why added grit or sand is so important.

(Read my article on how to revive dying herbs).

I have grown Mediterranean herbs in both climates with high rainfall (the Pacific Northwest) and climates with low rainfall (Southern California), and from this experience, I found out some interesting things about which potting soil is best for which climate…

In climates of high rainfall, I found that when I planted my herbs in grit (as opposed to sand), my herbs grew better and were less likely to suffer from root rot.

My takeaway from this is that grit has a larger particle size than sand, which increases the rate of drainage so that the soil dries out more quickly around the herb’s roots, which reduces the risk of root rot.

In fact, out of the 10 different Mediterranean herbs I grew in the Pacific Northwest, all 5 that were planted in grit lived longer and did not suffer from fungal diseases compared with 3 out of the 5 herbs that were planted in sand and compost.

Whereas when I was in Southern California, I found that my herbs grew well regardless of the composition of the potting medium (whether they were planted in sand or grit), which I attribute to the climate in Southern California being more similar to the Mediterranean climate, therefore drainage was not likely to be a serious problem.

More sand or grit is always better than not enough when it comes to the potting soil of Mediterranean herbs in rainy climates due to their sensitivity to excess moisture and preference for dry conditions.

Mediterranean herbs have adapted to grow naturally in soil that is usually pH 7, neutral or slightly alkaline pH 7.1-8, but they can tolerate some moderate acidity of pH 6.5.

All the multipurpose compost and potting soil that I’ve seen sold commercially is usually pH 7 and is appropriate potting soil for all Mediterranean herbs.

However, I must caution you against using ericaceous (acidic) soil, which is usually around pH 6, as this is too acidic for Mediterranean herbs, which prevents the roots from taking nutrients and can kill the plant.

Best Potting Soil for Basil, Cilantro, Mint, Chives and Parsley

It is important that we make this distinction…Whilst herbs such as basil, cilantro (parsley), mint, fennel, dill, and chives can be used in Mediterranean cooking, they are not native to the Mediterranean region and, therefore, require different soil conditions to the native woody Mediterranean herbs.

Herbs that do not originate from the hot and dry Mediterranean climate require potting soil with a greater capacity to retain moisture for the roots to uptake when required.

Generally speaking the best potting soil for herbs such as basil, mint, and cilantro is good quality multipurpose compost as it retains moisture to prevent wilting yet allows excess water to drain away. Multipurpose compost also has the right balance of nutrients and soil structure to ensure an intense flavor and allow the roots to establish.

Well-rotted garden compost composed of garden waste and kitchen scraps (such as vegetable peelings) is also appropriate for potting up most non-Mediterranean herbs due to its favorable structure and moisture-retaining capacity.

Whilst potting compost, retains moisture it also has a friable structure that allows excess water to drain easily away rather than pool around the roots and cause root rot.

(Read my article, how often to water herbs).

Multipurpose compost (available from garden centers or online) does not need to be amended with other materials when growing herbs such as basil, cilantro (parsley), mint or chives as additional inorganic material (such as sand or grit) causes the soil to drain quicker then required which can cause these herbs to droop.

My experiment…

However I have some first hand experience to share with you regarding the best potting soil for herbs in warm climates. When I lived in Southern California I struggled to grow my basil and clinatro outdoors as they often wilted due to the extreme heat in the Summer.

So, I extensively tested the best potting soil for these leafy annual herbs. I tried multipurpose compost, manure, garden compost, and leaf mold to amend the potting soil to help retain moisture and prevent my herbs from wilting.

My findings…

What I found was that my herbs grew much better in the Summer when they grew in a mix of multipurpose compost (which I bought from the store) with around 50% leaf mold (which is just composted leaves).

The leaf mold had an incredible capacity to hold moisture, more so than the other soil amendments, so that my herbs were far less likely to droop in the summer regardless of the heat waves.

It really made a difference. The next year I tried mixing 50% leaf mold with compost composed of composted kitchen scraps, and I found that not only were my herbs more reliant on drought, but the added fertility from the kitchen scraps seemed to boost growth compared to my other herbs that were planted in conventional potting soil.

So from now on, I use a 50% kitchen scraps to 50% leaf mold potting mix for my herbs, and they grow fantastically!

The moisture retaining capacity of the potting soil is the primary reason for the difference of preference of potting soil between herbs that originate from the Mediterranean which tend to be woody in structure whereas other herbs such as basil rely on a constant source of moisture at the roots and consistent transpiration from the leaves to maintain turgor pressure which allows the herbs to stand upright in the absence of a woody structure to support them.

Potting Soil to Avoid for Basil, Cilantro, Mint, Chives and Parsley

Most non-Mediterranean herbs are not fussy growers when it comes to potting soil but there are some soil amendments that you should avoid that we need to be aware of…

• Avoid planting herbs in potting soil that has been amended with added nutrients.
• Avoid soil amendments such as coffee grounds or manure due to their high nitrogen content.
• Any potting soil amended with a high proportion of sand or grit.

Herbs such as basil smell and taste potent and distinctive because of the concentration of essential oils in their leaves. (I love the smell of fresh basil in the mornings!)

If you plant herbs in potting soil that is high in nutrients whether it is from prepared potting soils or amendments such as manure, because this can promote foliage growth but decrease the concentration of essential oils which reduces the intensity of the taste and smell of your herbs.

Here’s a mistake that I made personally…Avoid adding coffee grounds to the potting soil when growing herbs. Coffee grounds are high in nitrogen which can reduce the taste and aroma of your herbs and cause excessive drooping foliage growth which leaves the herbs more vulnerable to pests and disease.

Leafy herbs that lack a woody structure also rely on a constant source of moisture to help maintain their structure and prevent the herbs from drooping.

Any added sand or grit can cause the soil to drain too quickly, resulting in herbs that turn yellow and wilted due to drought stress.

(Read my article, choosing the best pots for herbs).

If you have any more questions on potting soil for herbs or have any insights you care to share, then please leave a comment below! I’d love to hear from you!

Key Takeaways:

• The best potting soil for Mediterranean herbs is a potting mix of two-thirds compost to one-third horticultural sand or grit. Added grit or sand replicates the optimal soil conditions of the herb’s naturally preferred soil type with good drainage, low to medium fertility, and an aerated soil structure.
• The best potting soil for basil is good-quality multipurpose compost, which retains moisture yet also has good drainage, moderate fertility, and a light aerated structure for the basil’s developing root system. Potting soil too rich in nutrients reduces the strength of the basil’s flavor and aroma.
• Do not add coffee grounds to potting soil for herbs as the high nitrogen content promotes foliage growth but reduces the flavor and aroma of the herbs. Coffee grounds in potting soil can cause herbs to droop and weaken the herbs, making them more vulnerable to pests and diseases.
• The best potting soil for lavender is a potting mix of 1/3 horticultural sand or grit to 2/3 multipurpose compost, which emulates the natural soil conditions of lavender’s Mediterranean home range. The balance of sand and grit ensures the soil drains efficiently to provide the optimal balance of moisture and nutrients and avoid root rot.