Thyme in pots – Complete Guide
Any type of Thyme, given the right conditions, can be grown in pots.
Any Thyme is an ideal plant to grow in pots because they are drought-tolerant plants that need poor soil with good drainage, which is simple to provide when grown in containers.
Thymes are perfect for outdoor pots because some are quite cold-hardy, and the more tender types, if kept in smaller pots, can be easily moved to a shelter during the winter. I have prepared a Thyme hardiness chart to guide you on the best ones for your climate.
There are many possibilities for thyme in pots, and the type you choose will depend on your preference for the flower and foliage colour, shape, and fragrance.
You may prefer more spreading types like Thymus serpyllum and T. ciliatus or cushion-shaped ones such as T. capitatus, T. citriodorus, T. vulgaris, T. pulegiodes, T. camphoratus or T. zygis. If you would rather plant one with a more upright growing habit and lots of fragrance, then T. mastichina is the best choice. I just mention the true species but there are many more varieties you can choose from.
But whichever one you choose will need the right conditions. The article will guide you through the steps you need to take to grow Thyme in pots successfully.
How to plant Thyme in pots
In this section, we will walk through the key points you need to consider when planting a Thyme in a pot.
Choosing a pot for Thyme
When you choose a pot for your Thyme, you should consider other important things besides aesthetics.
Anything that can hold soil and drain water at the bottom can be used as a plant container. However, the container’s size, shape and material are key in determining the success of your potted plants. These key aspects directly affect the water availability and insulation of your plant.
The container size
The general rule is the larger the plant, the larger the container. However, thymes are not very tall, but some can spread quite a bit, such as Thymus ciliatus or T. camphoratus which can spread up to 50 cm (20 in) or more. For these plants, you must consider a larger container to accommodate the spread. A tall vertical container will let the stems cascade down which looks lovely. You can also opt for a wide horizontal container, but in this case the water retention is higher so you need to water the plant accordingly.
However, when growing plants in containers, they will not reach the same size as when grown in the ground. Pots limit the growth of roots and, therefore, the size of plants.
Basically, the container needs to be big enough to provide room for the roots, hold the necessary water for the plant, protect from winter temperatures, and be stable not to tip over.
If your pot is too small:
- The Thyme will become rootbound, and growth will be stunted.
- The soil will dry out quickly.
- It will be more exposed to winter temperatures.
- It may fall over easily because the pot is unstable for too big of a plant.
If your pot is too large:
- The soil will stay wet for too long because the roots will not be able to absorb water from all the soil. This will cause the roots to stay damp and possibly rot.
Aesthetically the size is also important. There needs to be a balance. A common design rule is the container should be about half the height of the plant. But in the end, it is really up to your taste, of what looks more pleasing to you.
I suggest you choose the size of your pot based on the size of the pot the thyme is currently in. As a general rule of thumb, you should upsize 5 – 10 cm (2 – 4 inches) in diameter. This will allow extra room for growth as the thyme matures.
The plant will be better off if you change the size of the pot as it grows, instead of planting it in a large pot right away.
Your thyme will give you 2 important signs that it needs to be repotted, such as:
- It needs to be watered more frequently
- The roots start growing out of the drainage holes.
Generally, the thyme will need to be transplanted once every two years until it grows to mature size. Nevertheless, keep an eye on it for the signs.
The best time to change your thyme to a new pot is during the spring.
Make sure the container is larger than the current one, has sufficient drainage holes and has good-quality soil.
Remove the thyme from the current pot, loosen its roots and then place it into the new container. Cover the roots leaving some space below the rim to allow room for watering. Finally, water it thoroughly.
The Container Shape
When choosing the shape of your container, you should consider not only its ornamental characteristics but also its stability and water retention.
The shape of the container determines if it´s stable enough to keep the plant from falling over with the wind. This is especially important if the thyme is tall and dense.
Square and rectangular pots are the most stable. Then come the cylinder pots. Finally, the least stable ones are the more traditional inverted cones which tend to tip over easily.
The shape of the container affects the water retention capacity. Even when containers have the same volume and potting mix, water will dry out faster in a tall, narrow container than in a short, wide one.
This is due to the perched water table, which will be at the same height regardless of the shape and size of the pot.
The image shows two pots with the same volume and potting mix and, therefore, the same perched water table height.
As you may see, the tall, narrow pot holds less water than the short, wider pot. Also, the water is further away from the roots in the taller pot.
So with this in mind, and knowing that thyme plants have quite deep roots and need good drainage, you will choose a pot that is preferably tall and narrow.
The container material
The material that the pot is made of should also be considered when selecting a pot for your thyme. There are different materials, such as Plastic, Metal, Cast cement, Terracotta, Glazed clay, Wood and many more.
The material has a significant impact on the drainage of the soil and the insulation of the roots.
Pots made of plastic, metal and glazed pots will resist water loss and keep the soil moist for longer.
Pots made of porous material such as terracotta or wood will soak water from the soil and release it easily, enabling quick soil drainage.
For your thyme, which prefers dry and well-aerated soil, you will want to choose a pot with a more porous material such as terracotta or wood.
The temperature of pots with a porous material such as terracotta and wood will not fluctuate as much as plastic or metal materials. Therefore the porous material is a better option to insulate the roots from extreme temperature fluctuations.
However, in the winter, terracotta pots have the inconvenience of breaking easily with freezing temperatures.
This happens because the water that gets into the pores will expand when frozen, cracking the pot. So to minimize this, you may want to wrap the terracotta pot with plastic to prevent it from getting wet.
The best soil for thyme in pots
Mediterranean plants, such as thyme, need well-aerated soil with good drainage. Soggy soil is a real problem for them.
If you want your thyme to be happy, you will need to imitate its natural environment as well as possible, starting with the soil.
The potting medium for your thyme should have the following characteristics:
- Well aerated
- Good drainage
- Hold on to nutrients
- Retain some moisture
There are many recipes for potting mixes, but for drought-tolerant plants like thyme, you will need to add more quantity of an ingredient with large particle sizes, such as coarse sand, vermiculite or perlite. This is necessary to ensure the potting mix has excellent drainage and aeration.
The image shows how the amendment with a large particle-sized ingredient (ex: coarse sand, vermiculite or perlite) affects the soil’s drainage.
How to care for thyme in pots
If we plan to grow thyme in containers, we must not forget that plants in containers are more susceptible to the dryness of the soil, the effect of extreme temperatures and the inaccessibility to nutrients.
Thymes are tough plants and tolerate harsh environments. However, they still need special attention when grown in containers.
Because containers have a limited quantity of soil, watering and fertilizing become necessary, even for established thymes. Additionally, the roots in a container are more exposed to temperature fluctuations, so care must be taken to protect the roots.
How often to water thyme in pots
Even though thyme plants are drought-tolerant, and do not need to be watered once they are established, this is not the case when they are grown in containers.
How often you need to water your thyme will vary depending on the weather, the potting soil, the type of container, and the exposure of the container to sun and wind.
- Weather: During the winter, the plant will need much less water because it is not actively growing and is not as hot.
- Soil: If your potting soil does not drain easily, you must water it less frequently than if it has excellent drainage.
- Pot material: If your pot is made of a porous material, you will need to water it more frequently than if it’s made of plastic or a glazed material.
- Pot size: If the pot is smaller, it will need more watering than if it´s larger.
- Exposure: If your thyme is exposed to long hours of sun and winds, it will need more frequent watering than if it has some shade and is sheltered.
This means there isn’t a “one fits all” schedule for watering your plant. So you must observe your thyme regularly to see if it needs watering.
How to check if your thyme needs water
You should not wait for the plant to show severe signs of wilting due to insufficient water or die from excess moisture.
The easiest way to know if the plant needs water or has excessive moisture is to stick your finger in the soil and feel how dry or moist it is.
In the case of sandy soils, which are the best for these plants, I do not recommend using a moisture meter because even when the soil is moist, the probe cannot detect the moisture accurately due to the air pockets in this large particle soil. So the reading will always be “dry soil”, and you will inevitably overwater your plant.
How to water your potted thyme
In the case of drought-tolerant plants like thyme, you will need to let the soil dry out completely before watering again. The rule is to water deeply and infrequently.
When you notice the soil is dry, it is time to give it a deep watering. You must wet the soil completely until water drips out of the drainage holes.
After this, let it be until the soil has dried out again. You may be surprised by how long your thyme can go without water. You are better off giving it less water than overwatering.
If you notice a gap between the soil and the pot, then you should press the soil against the wall of the pot to close this gap. Otherwise, the water will flow right out through the gap. This is more common when you pot your plant, and the soil is not yet tightly pressed.
Finally, you may want to cover the soil with some mulch, ideally gravel, to help conserve moisture. This will also give some extra protection from the cold temperatures of the winter months.
Overwintering thyme in Pots
A thyme in a pot is less hardy than in the ground. This happens because the parts of the plant above the ground are hardier than the roots. When roots are out of the ground and inside a container, they are more exposed to cold temperatures.
Plants in pots are also more prone to freezing and thaw cycles. If your plant is in a sunny spot, as thyme should be, it can warm up considerably during the day and freeze at night, which is very hard on the root system.
So to minimize the problems, I have the following tips:
- Choose a thyme that is more cold-hardy than your zone ( generally 2 zones under).
- Plant in a large container (but always matching the size of the plant). The larger the pot, the more insulation it will have around the root system.
- If the pots are not too heavy, move them into a cold frame, a shed or a more sheltered location outside and cuddle several pots together.
- Dig a hole in the ground, place the pot inside and cover it to the brim.
- Wrap the pot with a thick layer of burlap, bubble wrap or straw.
Don´t forget to give your plant a deep watering at the end of the season and then keep an eye on it during the winter and water it when needed.
Usually, thyme will not need watering in the winter. Still, when they are in containers, they may need to be watered not to let the roots dry out which can easily happen in a container because of the limited quantity of soil.
Fertilizing thyme in pots
Like most Mediterranean plants, thyme prefers poor soils. However, when they are in pots with a limited amount of soil, they will consume all the available nutrients after a certain period.
So it is necessary to give them some fertilizer from time to time, to replace the nutrients.
Companion plants for thyme in pots
You can plant thyme in their own container or mix them with other plants that have the same hardiness, sunlight and water needs.
Cistus, Rosemary, Santolina, Lavender and Helichrysum will all go well with thyme plants
Considering plants that require the same conditions, you can freely choose the size, shape and colour combinations of your preference.