You might grow thyme because of its health benefits and how it brings lots of flavor to your meals. However, while it’s relatively easy to grow, you might find that your thyme plant is turning brown and dying. So, what causes thyme to die?
Thyme plants can die because they aren’t getting enough sunlight. Thyme needs to be in an area of the home or garden where it gets lots of natural light daily. Other reasons thyme can struggle to grow include if it’s overwatered or if its soil doesn’t have the correct pH.
In this article, I’ll explore these and other common reasons why your thyme keeps dying. I’ll also provide solutions regarding what you should do to bring your plants back to life.
1. Your Thyme Plant Is Getting Too Much Water
Thyme is a herb that you should care for by doing minimal work. It doesn’t want a lot of water, so don’t fall into the trap of watering it every few days, as this will make its soil too damp.
Thyme likes to grow in dry soil, so cut back on your watering schedule. You should water thyme every 10 to 15 days and give it one inch (2.54cm) of water.
It’s also good practice to stop watering your thyme plants a few weeks before the first rain is expected in your region, as they will get enough water. You should only water thyme if your region goes through two to three weeks without any rainfall.
Being careful not to overwater your thyme plant will prevent root rot, a condition that can be fatal for it. Some root rot symptoms include:
- Wilting leaves
- Leaves that become yellow or brown
- Stunted growth
- Sudden decline without any clear reason
- Rotten smell in the soil
It’s essential to treat root rot immediately, such as by reducing how much water you give your plant and transplanting it in fresh, well-draining soil so that you reduce the risk of it being fatal for your plants.
2. Your Thyme Plant Doesn’t Have the Right pH
Plants require the right pH, whether it be acidic, alkaline, or neutral soil. Thyme plants require a soil pH that’s between 5.5 and 7.0, which is slightly acidic to neutral, so make sure you test your soil regularly.
If you don’t have the right soil pH for your thyme plants, this will cause the following symptoms:
- Lack of growth
- Discolored leaves
You can test your soil’s pH with a home testing kit to measure soil pH, moisture, and how much sunlight your plants are receiving. This takes out the guesswork to keep your thyme plants alive.
3. You’re Not Pruning Your Thyme Plants
If you don’t prune your thyme plants, this can cause growth problems. The stems will turn woody in the plant’s center, and they’ll become brown and stop growing leaves properly, as SFGate reports.
However, pruning will remedy this issue quickly. Remove approximately one-third of the woodiest, oldest stems of the plant, and make sure you cut them back by half.
You should repeat this process every year to keep your thyme in good condition.
4. Your Potted Thyme Isn’t Getting Enough Drainage
Earlier, I mentioned the importance of not giving your thyme too much water. If you’re growing thyme indoors, you need to ensure you plant it in the correct pot that has good drainage.
Pots that are made out of porous materials, such as terracotta, are ideal for growing thyme. They remove excess water and prevent it from making the soil wet.
Check that your pot has drainage holes at the bottom. To further enhance drainage, you can add a layer of gravel on the bottom of the pot to prevent plant roots from being exposed to too much water. However, be sure to avoid blocking the pot’s drainage holes.
5. You’re Giving Your Thyme Too Much Fertilizer
Thyme plants are low-maintenance because they don’t need rich, highly-nourished soil in order to grow. You also don’t have to feed them fertilizer unless the plants are showing weak or stunted growth. However, if your thyme is looking worse for wear, you should feed your plants a balanced liquid fertilizer to encourage them to grow.
Additionally, if you’re giving your thyme fertilizer, you should feed it every spring. When using a 10-10-10 balanced fertilizer, make sure you apply it at half-strength so that you don’t encourage the plant to grow too many leaves. SFGate reports that these will reduce the strength of thyme’s fragrant oils. After fertilizing your thyme plants, make sure you water them thoroughly, as this evenly distributes the fertilizer’s nutrients through the soil.
Learn more about how to apply triple 10 fertilizer in my article here: The Complete Guide to Using Triple 10 Fertilizer
6. Your Thyme Plant Isn’t Getting Enough Sunlight
Although thyme plants need a lot of sun every day to thrive, full sun conditions can kill them very quickly. This is because the harsh sunlight puts too much stress on the plants and causes their leaves to become scorched.
To prevent this, keep your thyme plants in areas of the garden or home where they will receive between eight and 10 hours of indirect light. This type of light can be described as light that passes through a medium, such as leaves of a tree or window curtains, or reflects off a surface before it reaches the plant.
This will also prevent your plant from receiving too little sun, which is also problematic.
Not enough sunlight prevents the plants from being able to photosynthesize, which will kill them. This process produces energy for the plant so it can grow. Without it, the plant won’t receive the energy it needs, so it will die, as UCSB Science Line reports.
7. Aphids Are Attacking Your Thyme Plants
Thyme plants can be attacked by aphids, which are small insects that suck sap from plants. These common garden pests become problematic because they multiply rapidly. If you see them on the plant, wash them off with a strong stream of water, such as from a watering hose.
If this doesn’t work, you can try applying neem oil. This extract from neem tree seeds contains compounds that kill insects. It’s an effective repellent that’s especially good for killing immature, actively growing insects, as the University of Florida Gardening Solutions reports.
To apply neem oil, follow these tips:
- Mix one teaspoon of liquid soap in a gallon (3.7 liters) of warm water. Add two tablespoons of neem oil. You can purchase neem oil at retail shops or online.
- Put the ingredients in a spray bottle.
- Spray the neem mixture on a small area of your thyme plants. Leave it for 24 hours, so you can see if there is any damage caused to the plants.
- As long as your plants don’t display any damage, spray your plant leaves with the solution.
- Reapply the solution to your thyme plants twice a week to prevent aphids from affecting them. If you’re dealing with an aphid infestation, you can apply it to your plants once a week, as MasterClass reports.
If you consistently apply effective treatment methods, plants can recover from having aphids. I’ve written an extensive guide about the topic. Don’t miss it: Can Plants Recover from Having Aphids?
8. Your Thyme Plant Doesn’t Have Enough Humidity
It’s easy to assume that since your thyme plants don’t need a lot of water, they don’t need humidity, but this can set back your thyme plant’s growth and possibly even cause it to die.
Thyme requires 40% humidity. Fortunately, this amount is easy to maintain because the ideal indoor humidity level is around 40-60% anyway. That said, keep your thyme away from areas of the home that are prone to experiencing high humidity, like the kitchen or bathroom.
Self-watering pots can also help to prevent your thyme plants from getting too much water and humidity. They have hollow legs that reach into the reservoir, so the soil draws moisture, and they keep the plant above the water.
9. Your Thyme’s Pot Is Too Small
Although herbs don’t require a lot of room to grow, you should be careful not to give them a pot or container that’s too small. This can kill the plant, which will struggle to get enough nutrients.
Ensure that the pot is approximately four inches (10.16 cm) in height and four to six inches (10.16-15.24cm) in width. It should also be about six inches (15.24 cm) in height, as thyme has shallow roots that don’t require a lot of space in the soil.
If you’d like a more in-depth guide about repotting indoor plants and the benefits of having properly sized pots, you can read my other article here: The Ultimate Guide to Repotting Your Houseplants
10. Your Thyme Doesn’t Have Enough Potting Mix
Although small, the pot for your thyme plant needs to be large enough to contain one gallon (approximately 3.7 liters) of a potting mix so that it will have enough space to grow its roots.
Avoid using soil in your thyme pot, as this is too heavy. It easily becomes compacted, which will prevent air circulation for your plants.
11. You Moved Your Thyme Outdoors Too Soon
If you were growing thyme in containers indoors and now you want to transplant them into the garden, be careful not to do this too quickly as it can shock your plants.
You need to transfer them over a period of a few days to give the plants a chance to get used to their new environment. Here’s how:
- After planting the thyme into a new pot, leave it outside during the day and bring it inside at night.
- Slowly increase the time that you leave the pot outside over a period of a few days.
12. Your Thyme Has Been Attacked by Icy Weather
If you’ve experienced a very harsh winter in your region, your thyme plant might turn brown and look dead. The good news is that your plant might not actually be dead but just dehydrated.
To find out which one is the case, scrape the bark of some stems to see if they’re green. If so, the plant is still alive. As NC State Extension reports, you should avoid pruning it until new growth appears on the plant.
To prevent thyme from dying during winter, you should take some steps to protect it against the icy weather. These include the following:
- Avoid overwatering it. Since thyme is ideal for dry climates, you should avoid watering its soil too much. Standing water will make it vulnerable to icy weather and frost damage.
- Apply two inches (5.08 cm) of mulch. Mulch, such as pine bark, will encourage the soil to drain properly so that the herb can withstand cold conditions. Mulch will prevent ground freeze and thawing, so the roots of the thyme plant won’t be exposed to the harsh conditions, as Oregon Live reports.
- Shelter your plants. Place pots containing thyme in sheltered areas of the home. This will protect them against strong winds and rain.
Watering potted plants before a freeze is a tricky business. If you live in a cold region, you should know how to water your plants during winter. Check out my blog post for more information on this subject: The Complete Guide to Watering Your Plants in the Winter
13. Your Thyme Isn’t Getting Enough Air Circulation
If you’ve noticed that your thyme plants are experiencing fungal diseases, this could be what’s killing them. Fungal diseases usually strike when thyme plants are planted in the ground without enough space between them to encourage enough air circulation.
This is especially problematic if you live in a hot or humid region.
A common type of fungal disease is Alternaria blight, as Plant Village reports. This appears as follows:
- Holes in leaves
- Dropping or wilting leaves
- Small round brown, black, or yellow spots
To prevent this fungus from affecting your thyme plants, you should space the plants about 12 inches (30 cm) away from each other to encourage better air circulation.
14. Your Thyme Is Planted Next To Leafy Plants
It’s worth considering what companion plants you have for your thyme. While rosemary is a great herb that performs well when planted next to thyme because both of these herbs have similar watering requirements, if you’ve planted your thyme next to a leafy plant that sheds its leaves, this could be problematic for your thyme plant growth.
If you’ve already planted thyme with a leaf-shedding plant, don’t worry. You don’t have to transplant your thyme, but ensure you throw away any leaves that have decayed or dropped from the companion plant. If you don’t do this, the leaves could trap moisture around your thyme plant, causing issues such as mold, fungal diseases, and root rot.
15. Your Thyme Plants Are Infested With Spider Mites
Spider mites are common garden pests that like to suck sap from a variety of plants, including thyme. If you’ve fed your soil too much nitrogen, this can produce proteins that make sap taste sweeter to pests such as spider mites. This can cause more spider mites to infest the plant.
Signs your thyme plant has spider mites include the presence of what appears to be tiny black spots on your plant. Since spider mites are tiny, you might not see them on the plant, so look out for fine webbing around your plant.
You can eliminate spider mites with neem oil, which is regarded as a natural pesticide. You won’t be able to effectively remove these mites with regular insecticides as they are resistant to their effects. To use neem oil, follow these steps.
- Wet the plant and apply neem oil. Focus on applying it underneath leaves, as this is where they tend to go.
- You should reapply neem oil about once a week. If you’re applying neem oil to your thyme plants and it’s not getting rid of spider mites, this means you need to apply it more regularly.