Why Are My Herbs Turning Yellow? (How to Save Them)

Why are my herbs turning yellow

I think that fresh herbs are one of the greatest joys in life, so I understand there is nothing more disheartening than seeing your herbs turning yellow.

I grow almost all the popular culinary herbs every year, so I always have a supply to add a burst of flavor to my cooking. I have encountered all the problems that we are going to discuss in this article.

Through my research, personal experience, and trial and error, I can share with you some great tips and secrets to keep your herbs green. I’ll also tell you exactly what to do step by step if yours are turning yellow!

Most often, Herb leaves turn yellow because of overwatering or underwatering, which prevents the herb’s roots from transporting nutrients and water properly to the leaves, which causes them to turn yellow and drop off. Herbs with root rot turn yellow and have a drooping appearance.

I created the following table to help you identify the specific reason your herbs are yellowing:

Causes:Reasons for Herbs Turning Yellow:
Root rot is caused by overwatering, boggy soil, and pots without drainage.Root rot damages the roots of your herb and prevents it from drawing up nutrients and moisture, causing yellow, drooping leaves.
Drought stress is caused by underwatering, small pots, and poor soil.Drought stress causes annual herbs such as basil and cilantro to wilt and turn yellow when the soil is too dry.
Lack of sun.Mediterranean herbs require full sun (6 hours or more), whereas annual herbs require partial sun. Too much shade causes leggy growth and yellow leaves.
Nutrient-poor soil.Poor soil caused by a low soil pH or because of nutrient deficiency causes herbs to turn yellow.

Keep reading to learn my secrets for how to solve this issue…

Herbs Turning Yellow due to Root Rot and Fungal Disease

  • Symptoms. Leaves and possibly stems are turning yellow and brown with a drooping appearance.
  • Causes. Watering too often, slow draining soils or pots without drainage holes in the base.

I think at some point, all gardeners have encountered this problem, particularly with herbs that originate from the Mediterranean region of Europe…

The most common reason herbs turn yellow is too much moisture around the roots, which promotes root rot and fungal diseases. Root rot is caused by overwatering, slow-draining soils and pots without drainage holes in the base, and it causes the leaves to turn yellow and droop.

All of our herbs require well-draining, porous soil with a light, friable structure that allows water to infiltrate effectively.

If the soil becomes saturated, then herb roots can develop root rot, and they can no longer respire, which prevents them from drawing up the nutrients and moisture they need. If nutrients and moisture cannot reach the leaves, they turn yellow as a sign of stress.

All herbs suffer when there is too much moisture around the roots but our Mediterranean herbs in particular (lavender, rosemary, sage, thyme and oregano) are adapted to growing in dry sandy soils which drain very quickly and hold less moisture which leaves them more vulnerable to root rot.

For Mediterranean herbs, we need to amend the soil with sand or grit to emulate the sandy Mediterranean soil conditions and, ideally plant them in pots (with drainage holes in the base) for more favorable drainage and water them less often.

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

The key is to avoid planting herbs in clay soils or boggy areas as they retain too much moisture, and your herbs are likely to turn yellow and die back.

Parsley leaves turning yellow due to overwatering.
This is a photo of some parley I saw at a friend’s house. I was able to diagnose that the problem was root rot as the pot didn’t have any drainage holes, and the soil felt boggy.

How I Save Yellow Herbs with Root Rot

  • Scale back the watering. Mediterranean herbs typically require watering once every 2 weeks when in pots and do not require any water at all once established in garden borders. If you are watering more frequently than this, you are overwatering your Mediterranean herbs, and this is the most likely cause of your leaves turning yellow.
  • Annual leafy herbs such as basil, cilantro, dill, mint, chives, and parsley require consistently moist soil, so they should be watered more often than Mediterranean herbs. However, the soil should be evenly moist rather than saturated or boggy. I recommend using your finger to detect the soil’s moisture. It should feel moist to a finger’s depth but not boggy and smelly.
  • Improve the soil drainage. I have tested growing Mediterranean herbs with many different soil amendments and different levels of composition. What I found that works best is soil that is approximately 70% compost to 30% sand or grit, as this helps us effectively recreate the well-draining, gritty soil conditions of their native Mediterranean environment. Creating the right soil mix for Mediterranean herbs is critical to avoid root rot and yellow leaves, so watch my video on how to create the optimal potting mix for lavender. (please note that the same soil mix applies to all Mediterranean herbs).
  • Transplant your herb into a different pot with drainage holes in the base. As we discussed, our herbs should always be planted in pots and containers with drainage holes to allow excess water to escape after watering and prevent the soil from becoming saturated. Be careful of saucers and trays underneath your potted herbs, as these can keep the soil at the bottom of the pot damp and prevent water from draining away from the roots effectively.
  • When you are transplanting your herbs, inspect the roots. Trim off any dark roots that feel mushy, rotten, or have a bad smell. Roots should be lighter in color (they can look brown and woody on some herbs) and feel firm without any significant smell. Trim any diseased-looking roots back to healthy growth with a sterile pair of pruners. Wipe the blades of the pruners with a cloth soaked in disinfectant (I use hand gel) to prevent spreading any fungal pathogens to otherwise healthy roots.
Mint roots
Here are some rosemary roots on the right that have been overwatered. You can see how they have turned dark brown, mushy and I can personally attest they had a smell!
  • Replace the soil. Discard the old potting soil as it can host the fungal pathogens that are responsible for root rot so it could potentially reinfect the plant. Replant leafy annual herbs (such as basil and cilantro) in good compost and Mediterranean herbs in compost amended with sand or grit.
  • Cut back any yellow leaves. Any yellow leaves are not likely to recover if overwatering is the cause, so I always cut them back to the base of the plant with sterile pruners.

If most of the leaves of the herb are yellow or the roots are mostly rotten then the herb is likely to die so discard it and replant new herbs in different pots.

Preventing root rot is always better than trying to solve it, so the best option may be to replace the herbs and adhere to the best practices of watering (once every 2 weeks for Mediterranean herbs), planting herbs in the appropriate soil (amended with sand or grit for Mediterranean herbs) and planting your herbs in pots with drainage holes to prevent root rot and yellow leaves.

(Read my articles on the best pots for herbs, the best soil for herbs, and how to revive dying herbs for more information on preventing root rot).

Underwatering Causes Herbs to Turn Yellow

  • Symptoms. The symptoms of drought-stressed herbs are similar to those of overwatered herbs (somewhat confusingly), with yellow leaves and a wilted appearance.
  • Causes. Underwatering, small pots, soil that drains too quickly.

To distinguish whether your herbs are turning yellow from underwatering or too much water, drought stress is the cause if…

  1. The herb’s leaves are turning yellow from the bottom of the plant.
  2. The leaves appear wilted and can curl inwards.
  3. The soil feels dry and baked rather than boggy.

Mediterranean herbs are drought resistant, as they have adapted to the hot and dry Mediterranean climate.

They actually thrive in well-draining soils, so most of the time, it is overwatering that causes their yellow leaves rather than underwatering, although this can happen in pots that are too small.

This happened to me with my sage plants. They were in a small plastic pot in full sun at the height of Summer. The soil baked hard, and I noticed water just trickled off the surface without infiltrating properly and reaching the roots.

Yellow sage leaves because to drought stress due to being planted in a smaller pot.
These are my yellow sage leaves that turned yellow because of drought stress due to being planted in a smaller pot.

Our leafy annual herbs (such as basil, cilantro, parsley, mint, and chives) on the other hand are more likely to suffer drought stress which causes the leaves to turn yellow with a wilted appearance.

The leafy annual herbs require the soil to be moist (yet well draining) which is achieved by planting them in compost as compost can retain moisture, yet has a porous structure that allows excess water to drain away from the roots which is the perfect balance for annual herbs.

Of course, the right frequency of watering is also very important for preventing drought stress and ensuring every time it is a thorough watering rather than a light watering, so the moisture reaches the roots where it is required.

How I Saved My Yellowing Herbs Because of Drought Stress

  • Give your herbs a thorough watering so that excess water trickles from the base of the pot. Whether your herbs are planted in raised beds, garden boarders, or in pots they all require a generous soak to ensure the water reaches the roots. Light watering causes the roots to grow near the surface of the soil which increases the herb’s vulnerability to drought.
  • As for my sage plants, I had to submerge the whole pot underwater for 10 minutes to alleviate the stress of drought. As we discussed, the water was trickling off the surface as the soil had baked hard. The only antidote to this is to soak the whole root ball underwater, which allows the soil to absorb water properly.
  • Water leafy annual herbs so that the soil is consistently moist. How often to water your herbs depends on many variables, such as climate, weather, and soil, so my best advice is to ensure that the compost feels moist to a finger’s depth in the soil. When the soil starts to feel as though it is beginning to dry out, give your herbs a good soak. Typically, I find this means watering every 3-7 days, depending on the time of year, but watering leafy annual herbs nearly every day can be required at the hottest times of year.
  • Always plant your herbs in a larger pot of around 12 inches across, if possible. Herbs can grow perfectly well in small pots, but it should be noted smaller pots dry out much quicker in the sun as they have less capacity for soil and, therefore, less capacity for moisture. Larger pots have more soil and, therefore, hold more moisture for the herb’s roots to uptake water and nutrients as required.
  • Plant your annual herbs in good compost if your soil is sandy. Leafy annual herbs require good compost to avoid drought stress and yellow leaves. If your soil is sandy or stony, it is likely to drain too quickly for leafy herbs and therefore, it is better to grow your herbs in pots with good compost or significantly amend your soil with lots of organic matter (leaf mold and compost are the best materials for retaining moisture) to create the optimal balance of moisture for your herbs and prevent yellow leaves from droughts stress.

Pro tip: Here is a really great hack that I was taught by a herb gardener in a hot climate. Amend your potting soil with leaf mold if you are growing leafy herbs in a hot climate. Leaf mold is the best compost amendment as it can retain more moisture than any other type of organic matter, and it still has a porous structure to allow excess water to drain, which creates the perfect environment for your leaf green herbs.

Since I have started implementing this tip none of my herbs have wilted or turned yellow! Of course this advice applies to growing herbs like chives, corriander, mint, basil cilantro etc. and does not apply to the mediterrean herbs (rosemary, lavender, sage etc.) which need dryer soil.

Reviving herbs turning yellow from drought stress is a lot easier than from overwatering, and often, the herbs can make a good recovery if you create the optimal conditions and increase the watering.

I would still trim back any yellow leaves back to the base, and I can assure you, if you are taking good care of your herbs, they often grow back with vengeance! I have had to do this basil a few times and it always grows back nice green leaves.

The lack of Sun Could be Turning Herb Leaves Yellow

  • Symptoms. Poor stunted or very slow growth. Stems can grow leggy as the herb grows to the strongest source of light. Leaves turn yellow, usually from the bottom of the herb.
  • Causes. Mediterranean herbs require full sun (6 hours or more) and turn leggy and yellow in the shade. Leafy annual herbs (such as basil and cilantro) can grow in partial shade but turn yellow in full shade.

As we have talked about, our Mediterranean herbs thrive in full sun in their native range in Southern Europe, so locate them in the sunniest area of your garden, or they grow leggy, turn yellow, and die.

If your Mediterranean herbs have turned leggy, what I would recommend is to propagate them from any healthy growth, as Mediterranean herbs do not respond well to being pruned back as much as leaf herbs.

Here is my guide to propagating rosemary from cuttings (I love propagating as it is super easy and fun!).

For our leaf herbs, what I have done to address this problem is to trim back any leggy growth by at least one-third and with some herbs such as basil, back to the base to stimulate new growth.

My herbs recovered in 4 weeks with lots of new green leaves (but bear in mind I did this in Summer, and the growing conditions were favorable; it may take a little bit longer to recover if growing conditions are not as good).

Our leafy green annual herbs, such as basil, prefer morning sun followed by afternoon shade.

This allows them to grow to their best in the sun yet protects the herbs from drying out as temperatures peak in the midday and afternoon. When I lived in Southern California, I found it essential to hide my leaf herbs from the heat and sun of the afternoon.

If your leafy annual herbs are in too much shade, move them to an area of more sun and trim back any drooping affected growth, which stimulates healthy green leaves to grow, which have a much better culinary value.

Nutrient Poor Soil Can Causes Herb Leaves to Yellow

Leaves of rosemary turning yellow.
Leaves of rosemary turning yellow.
  • Symptoms. Poor stunted growth, with leaves yellow and brown.
  • Causes. Sandy soil or smell pots that have limited soil and therefore limited nutrient availability.

We need to remember that our Mediterranean herbs are native to Southern Europe and grow in sandy, gritty soils that are medium to low in nutrients.

Therefore, herbs such as lavender and rosemary actually thrive in nutrient-poor soil, so the reason they are turning yellow is more likely due to overwatering or damp soils.

However, Mediterranean herbs typically prefer a soil pH of 6.5-7.5, so if your soil is particularly acidic, then this can prevent the roots from drawing up certain nutrients in the soil, which can cause foliage to turn yellow.

If your garden soil is very acidic (lower than pH 6.5) then always grow herbs in pots instead (which is what I recommend).

Commercially available compost and potting soil are within the appropriate pH range to grow herbs unless it is ‘ericaceous’ compost, which means that it is formulated for plants that prefer acidic soil conditions.

Leafy annual herbs such as basil and cilantro grow best in compost or in a vegetable garden amended with organic matter (which contains more nutrients) rather then sandy soil which can cause the leaves to turn yellow due to a lower concentration of soil nutrients.

My own annual herbs that were planted in a relatively small pot have sufferd a nutrient deficiency and turned yellow before.

I was able to diagnose that this was because the smaller pot had less soil and, therefore, less nutrients available for the roots, which caused the leaves to turn yellow.

My solution was to replant my herbs in a larger pot with new compost, and my herbs recovered and started growing again.

You can also add some fertilizer, I try to avoid using chemical fertilizers on my herbs so I use organic fertilizer in the form of liquid seaweed, which i think is magic as my herbs grew back and looks fabulous in 3 or 4 weeks! It really improved my harvest.

Of course, I cut back any yellowing foliage to stimulate new growth, which was healthy and green.

Can You Eat Yellow Herb Leaves?

No. Do not eat the yellow leaves of herbs, as they are unlikely to taste very good and contain a much lower concentration of the essential oils that give herbs their aroma and flavor. Instead, prune back your annual herbs to around 8 inches tall to stimulate new growth of healthy green leaves with a much better flavor.

If you have any more questions, please leave a comment below, and I’ll get back to you!

Key Takeaways:

  • Herb leaves turn yellow because of root rot caused by overwatering. Overwatering herbs prevents root respiration, which interferes with the root’s ability to draw up moisture and nutrients from the soil. As a sign of stress, the leaves turn yellow and droop.
  • Herb leaves turn yellow because of dry soil. Annual herbs such as basil and cilantro require moist, porous soil and frequent watering in hot weather to prevent leaves from turning yellow and wilting. Small pots dry quickly in the sun, causing herbs to turn yellow as a sign of stress.
  • Mediterranean herbs require 6 or more hours of sun, whereas annual herbs require partial sun and turn yellow with poor growth in too much shade. Move your herbs to a sunnier location and cut back any yellow growth to stimulate healthy green leaves.
  • If your soil is sandy or gritty or your pots are very small, annual herbs such as basil and cilantro can turn yellow due to a lack of nutrients. Repot your herbs in a larger pot with good compost and cut back yellow leaves; the herbs should recover.

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