Red Leaves on Thyme Plant: 7 Likely Causes & How To Remedy

Thyme has been used for centuries to add flavor to dishes and for its healing properties. While it is typically green, there may be instances where the leaves turn red. This may seem confusing, but the reason behind it may astonish you.

Why does thyme turn red? The leaves of thyme could turn red due to inadequate watering, too much water, temperature fluctuations, the wrong soil pH, or lack of nutrients. You’ll need to examine the plant and the growing conditions to determine the cause of the change of color in the leaves and remedy the situation.

Thyme is quite a sensitive plant, and it might respond to changes in the growing conditions by turning red. Read more to find out how to determine the cause of the red leaves and fix it.

Red Thyme – Possible Causes & Solutions

Red leaves on thyme is a condition caused by inadequate or improper growing conditions. Although some thyme varieties naturally produce reddish leaves, if your once-green thyme is now producing different coloration in its leaves, something is likely wrong in its growing environment. These are the common causes of thyme leaves turning red:

1. Too Much Water

Thyme doesn’t require much watering. In fact, it only needs occasional watering and doesn’t like to sit in waterlogged soil. Too much water could damage the roots and interfere with normal nutrient uptake, thus causing leaf discoloration.

What To Do

Once established, only water thyme once a month or once every two weeks. Make sure the soil drains readily to prevent water-logged soil and protect the sensitive roots. 

2. Lack of Water

Although thyme is a drought-hardy plant, it still needs water occasionally. Forgetting to water the herb for weeks on end might cause the leaves to turn red before the plant withers and dies.

What To Do

Ensure that the plant gets water at least once a month. If the soil is totally dry, water the plant immediately to revive it. 

3. Nutrient Deficiency

Poor soil doesn’t provide thyme with the necessary nutrients to produce enough leaves with their rich oil. A lack of basic nutrients such as nitrogen and potassium could stunt the growth of the plant and result in discolored leaves.

What To Do

Apply a balanced and general-purpose fertilizer once every spring. Use a liquid fertilizer at half strength to manage the size of the foliage and improve oil concentration in the leaves. I always see good results with this organic fertilizer.

4. Sudden Changes in Environmental Conditions

As a Mediterranean native, thyme thrives in full sun and needs at least 8 hours of sunlight every day during the growing season. Transplanting thyme in areas of poor light or partial shade could cause the leaves to turn red as would other sudden, extreme changes to its environment.

What To Do

If you don’t have a spot in the garden that gets 8 hours of sun daily in the spring and summer, consider planting the thyme in pots or planters and moving them around the sunny spots.

5. Cold Temperatures

Although thyme is usually cold hardy, it will go dormant in the frost or if the temperature drops suddenly. Sometimes, this might result in reddish leaves.

What To Do

Ensure that the plant is basking in warm temperatures between 65 and 85 degrees Fahrenheit If you’re worried about cold spells, bring it indoors until the weather warms up again.

6. Incorrect Soil pH

Thyme can thrive in different soil pH levels ranging from 6.0 to 8.0, but if the soil becomes acidic or alkaline, the leaves will turn red.

What To Do

Amend the soil pH using lime or sulfur to bring it to the ideal range of neutral to slightly acidic. Check the soil periodically (this meter is easy to use and also monitors moisture, light, and nutrients) throughout the plant’s life to ensure that the pH hasn’t changed drastically.

7. Normal Coloration for Your Thyme Variety

As mentioned, some thyme varieties, like red creeping thyme, have red leaves. That’s not a condition, and the plant is perfectly normal. 

What To Do

You only need to worry about thyme leaves turning red if they were normally green to begin with. If your thyme variety is a natural red, then you have nothing to worry about.

Is Red Thyme Edible?

If thyme is red for lack of watering or other adverse growing conditions, the red leaves are still edible. However, they won’t have as much oil as green and healthy leaves. As for red creeping thyme and other red varieties, the leaves are naturally red and edible although they’re too small to make an impact.

Quick Guide To Growing Thyme

To grow thyme, you’ll need to make sure that the growing conditions are favorable to the plant. Here’s what you need to pay attention to.

Soil for Thyme

As long as the soil is drains quickly and doesn’t retain water, your thyme won’t have any issues with it. From loamy to sandy and even full of gravel, thyme can thrive in different types of soil. However, avoid heavy or clayish soil as they might retain too much moisture for thyme to thrive.

Thyme Light Requirements

Thyme needs to be flooded with sunlight to improve the oil concentration in the leaves. The plant needs at least 8 hours of full sun in the spring and summer.

Thyme Water Requirements

Thyme can survive on minimal amounts of water. In fact, the less water it gets, the more fragrant and tasty the leaves become. Water it once every 3 to 4 weeks for best growth.

Fertilizing Thyme

Apply a liquid fertilizer once in the spring. Use the fertilizer at half strength to prevent a sudden burst of foliage growth that dilutes the oil and fragrance in the leaves.

Harvesting Thyme

You can start harvesting thyme leaves once the plant establishes. You can cut the stems and leaves together, but don’t harvest more than one-third of the foliage at one time.

Related Questions:

How Long Does Thyme Take To Grow?

In the right conditions and under full sun, thyme will take about 70 days to grow from seed to maturity. After that, you can start harvesting the leaves.

How Many Varieties of Thyme Are There?

There are hundreds of thyme varieties to choose from; however, out of the 300 known thyme varieties, only a handful have the desired oily and fragrant leaves. Recommended varieties include Golden Lemon thyme, Woolly thyme, Caraway thyme, and creeping thyme. 


The leaves of thyme are usually green unless you have a variety that produces red leaves naturally. If the green leaves turn red, check the soil pH, temperatures, lighting, and water in the soil.