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Why Do Herbs Have White Spots? (Let’s Find Out)

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Last updated on September 23rd, 2022 at 04:56 pm

Growing herbs is typically an exhilarating experience. Once the regular maintenance you’ll have to provide for your plants becomes routine, you will enjoy gardening.

Nonetheless, there are some periods when you’ll experience some setbacks and lose hope in your crops. One of such situations is when you notice white spots on your herbs. This anomaly may cause you to be worried, whether you’re new to gardening or not.

So, you may ponder, “why do my herbs have white spots?” In herbs, the appearance of white spots results from a limited number of reasons, such as nutrient deficiency, pest infestation, and disease. While this is not a death stroke for herbs as they continue to combat this anomaly, the white spots become even more visible as the weather remains hot and dry for much longer.

Why Does My Thyme Have White Spots?

White spots on thyme are caused mainly by pest infestation. As a herb, thyme is generally resistant to deer and rabbits yet susceptible to insects and pests. This susceptibility is because thyme is very rich in nectar; no wonder it is such an aromatic herb!

Just as we are endeared to thyme because of its aroma, so are insects and pests attracted to thyme foliage. Common pests of thyme like Thrips, spider mites, leafhoppers, and whiteflies enjoy feeding on the abundant nectar in the leaves of thyme.

Though many of these insects are tiny, their presence and actions are vividly reported on the leaves of thyme through the white spots spread about on the surface of the leaves.

These white spots represent a loss of nutrients in the areas where these insects have fed. For example, Thyme foliage with white spots would not necessarily cause the death of the plant, and the foliage would remain edible.

However, these attacks would significantly reduce its flavor and potency.

Nonetheless, you can curb this by simply hand picking these pests where visible. If this poses a challenge, you can also flush the entire foliage with running water, but you must ensure that the water does not accumulate in the soil.

Doing this will rid your thyme of white spots and restore its lush green aromatic foliage.

Why Does My Basil Have White Spots?

With Basil, the foliage is the edible part of the entire plant. As a result, any anomaly in the plant is always and most times first reported in the foliage.

The presence of white spots on Basil can be caused by a fungal disease called powdery mildew. Unlike other causes, when white spots are caused by powdery mildew, the white spots appear on both sides of the leaves and mostly affect leaves closer to the soil.

This characteristic appearance is because powdery mildew, a fungus, is caused by excessive moisture in the roots of Basil below the soil. Again, this is why powdery mildew is dominant in humid temperatures where fungus thrives.

White spots in Basil could also indicate an iron deficiency. Though iron is a micro-nutrient required in trace amounts, the total absence of Iron in Basil will immediately become evident with the appearance of white spots.

Interestingly, the soil where Basil is planted may contain sufficient amounts of iron. Still, if there is excessive moisture in the soil, the root may rot and become incapable of transporting this required nutrient to the leaves.

So, whether powdery mildew or an iron deficiency, the soil’s underlying cause is excessive moisture. Therefore, in these cases, proper watering and draining of the soil would revert white spots on Basil.

Additionally, though they do not typically inhabit Basil, the feeding activities of pests such as aphids, thrips, and especially leaf miners and mealybugs can cause white spots on Basil.

These pests frequently visit to obtain feeding from the Basil leaves, and when they are done, leave traces of white spots on the Basil leaves.

Here again, the foliage remains edible, and you can combat these pests by flushing leaves with soapy water, handpicking as well as the use of natural predators such as spiders, ladybugs and soldiers beetles.

Why Does My Oregano Have White Spots?

As soon as conditions become less than ideal for Oregano, this herb does not delay in showing its discomfort. If you have observed white spots on your oregano, then the herb is experiencing discomfort in a significant way.

This discomfort specifically originates from the roots of the plant. Like many herbs, Oregano delights in sunlight and heat. However, Oregano, when growing, spreads covering the main stem and roots.

Usually, this is no problem, but when the gardener is guilty of overwatering or the temperature falls steeply, this provides an ideal condition for fungi to thrive.

In the case of Oregano, rust is the most common fungal disease caused by excess moisture in Oregano, and it is responsible for the appearance of white spots in Oregano!

Caught early, pruning off the affected foliage alongside draining and drying up the soil will restore Oregano to full health with white spots absent.

Oregano is also attractive, and its foliage is rich in nectar. This feature makes it attractive to pests whose feeding activities depreciate Oregano foliage.

Leafhoppers and thrips are more common with Oregano, and with their presence come white spots which they leave behind on foliage after feeding.

I would never recommend using pesticides on herbs. If handpicking proves too difficult, feel free to keep flushing foliage with running or soapy water. However, take care not to flood the soil!

Why Does My Catnip Have White Spots?

With such broad, lush green leaves on healthy Catnip, the appearance of tiny white spots easily becomes conspicuous. So far, I have only discovered two main causes of white spots on Catnip which, however, should not be overlooked.

The first cause of white spots on Catnip is spider mites, a dominant pest of Catnip. Though a very tiny insect, when a spider mite infects your Catnip, you should be alarmed.

When caused by a spider mite, white spots result from toxins infused by the mites when they pierce and feed on Catnip leaves.  The problem here is that these white spots are only a start.

If neglected, the spots spread, and the leaves eventually become dry and turn yellow. The spots do not transfer from leaf to leaf, but the mite can! So, intervene immediately by flushing your herb and pruning off infected leaves.

Powdery mildew can also cause white spots on Catnip. Though unusual, it remains a possibility that it can result from fungi infestation from excessive moisture in the roots of Catnip.

The appearance of Powdery Mildew is eliminated by proper watering and a good draining soil for Catnip.

Why Does My Mint Have White Spots?

If you are cultivating Mint, you signed up for a spread of aromatic leaves but surely not for a spread of white spots on them.

When you notice white spots on your Mint, it could be caused by fungal disease, pest infestation, or a deficiency in nutrients.

The fungal disease, Powdery Mildew, is responsible for the white spots on Mint. Powdery mildew has become a constant feature in our discussion, and you should be familiar with it by now.

As a reminder, though, this disease is encouraged by excess moisture in the root of herbs. In Mint, however, powdery mildew becomes a bit more difficult to detect since the powder blends in with the deep green foliage.

Moreover, pests of Mint such as thrips, whiteflies, and spider mites suck out leaf juice from Mint, leaving behind tiny holes and white spots on Mint leaves.

When caused by pests, white spots in Mint is no cause for alarm except when a large colony infests the plant. In addition, iron and manganese Deficiency in Mint can cause white spots to appear on the leaves.

As stated earlier, this deficiency in the leaves could also result from root rot which impedes nutrient and mineral transportation.

The prevention and restoration of white spots on Mint follow the same pattern as discussed for Oregano above.


Very few biotic and abiotic factors, many of which are within our control, cause the appearance of white spots on herbs.

Yet, with herbs, the appearance of white spots each season remains constant. But with proper guidance from this article, you can always make a stitch in time to preserve the potency of your favorite herbs.


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