Planting thyme: growing, care & overwintering

An essential part of any garden and loved by pollinators, thyme is easy to grow and care for. With its aromatic leaves and many culinary uses, it needs little space and is perfect for growing in a pot near the back door ready to harvest from.

Thyme (Thymus vulgaris), a woody and evergreen dwarf shrub native to the Mediterranean, is a member of the mint family (Lamiaceae), along with basil (Ocimum basilicum) and oregano (Origanum vulgare). There are many varieties, flavours and foliage colours to choose from, but the most commonly grown thyme in the UK is the Common or Garden Thyme (Thymus vulgaris).

Planting thyme

Thyme is native to the Mediterranean, so it is no surprise that it enjoys a warm, sunny location with a well-draining soil. However, with a hardiness rating of H5, indicating that it will survive temperatures as low as -10 °C to -15 °C , it should survive all but the harshest of winters.

When to sow thyme

Whilst growing thyme from seed is possible, it can be tricky to germinate and can take up to a year before you can begin to pick it. Thyme seeds are best sown in spring, so they have time to establish before the arrival of winter, and they need to be sown somewhere warm as thyme needs temperatures of 15 °C to 20 °C to germinate. However, the easiest and most common method of growing this herb is to propagate thyme by division or from cuttings in spring, which will produce true to parent plants.

Thyme growing conditions

Thyme grows best in full sun in a light, free-draining, sandy soil that is not overly rich. While thyme can tolerate some partial shade, it may struggle and flower less if shaded too much.

Planting thyme: step-by-step

Growing thyme from seed:

1. In March to April, sow thyme seeds thinly in a seed or module tray filled with damp sowing compost.
2. Cover the seeds very lightly with a fine dusting of compost but do not fully cover with compost as thyme seeds need light to germinate.
3. Place the seed tray on a bright windowsill at 15°C to 20°C and keep the soil moist.
4. When the seedlings are large enough to handle, prick out and plant into individual 9cm pots.
5. When the plants are about 10 cm high, and there is no longer any risk of frost, gradually harden them off to acclimatise to the outdoor temperatures and wind before planting out.
6. Once hardened off, plant outside in their final position and water in.
7. Keep harvesting to a bare minimum for the first year.

Propagating thyme

Dividing thyme:

1. Carefully dig out a healthy and mature thyme plant on a fair day in late spring using a spade or trowel.
2. Remove all excess soil to make the root system more visible.
3. Tease the plant apart into 3 – 4 pieces, each with their own roots and foliage.
4. Plant the newly divided plants in individual pots or back into the ground. Press the soil down around the plant and water thoroughly.

Growing thyme in pots

Growing thyme in pots or containers is an excellent way to make sure the plant receives the conditions it requires, as a suitable soil can be chosen, and the pot can be easily moved depending on the season.

When choosing a pot to grow thyme in, porous materials like terracotta are often favoured because it helps avoid waterlogging. Thyme generally struggles in a small pot with a limited amount of soil, so it is best to use a 5L or 15cm – 20cm pot with adequate drainage holes. To improve drainage, add a layer of gravel or grit to the bottom of the pot to keep the thyme’s roots from sitting in water for too long.

Fill the pot with a free-draining compost mix that is not too rich in nutrients, like our Plantura Organic Herb & Seedling Compost. It is ideal for growing thyme as it is relatively low in nutrients and has a light and airy structure.

Repot thyme every year or two, or when it has outgrown its current pot, or its roots are growing out of the bottom. This is best done in spring or autumn, and if desired, divide the plant into several smaller plants at the same time.

Thyme plants are fairly drought tolerant and can deal with a certain amount of neglect. However, thyme in pots will require more frequent watering than plants grown directly in the ground.

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The best companion plants

When growing different types of herbs, it is best to plant those with similar growing requirements together, as not all herbs like the same conditions. Sage (Salvia officinalis) and rosemary (Salvia rosmarinus) both prefer full sun and a free-draining soil, making them great companion plants for thyme.

Other herbs such as tarragon (Artemisia dracunculus), basil (Ocimum basilicum), and chives (Allium schoenoprasum) prefer a moister soil than thyme and should not be planted together.

It is also best to avoid growing thyme and most other plants with mint (Mentha) due to its invasive root system.

Other mutually beneficial companion plants for thyme include:

• Strawberries (Fragaria × ananassa): One of the most common pest strawberry plants faces is worms, which can be naturally deterred by growing thyme either around your strawberry plants or in between rows, and it will help control weeds by providing ground cover.
• Potatoes (Solanum tuberosum): A staple crop of home-gardeners, potatoes can benefit from growing alongside thyme as it is said that thyme can improve their flavour and attract pollinators.
• Cabbages (Brassica oleracea): Here in the UK, cabbages and other brassicas are unfortunately very susceptible to damage from the cabbage white butterfly (Pieris rapae & Pieris brassicae), whose larvae can decimate a crop. Planting thyme can be beneficial for cabbages as thyme is a natural deterrent against these and other pests.

Thyme plant care

Caring for thyme plants is relatively easy, as once they are established, they require little maintenance apart from watering and feeding as needed.

Watering and fertilising

Thyme thrives in Mediterranean-like sunny, warm conditions and is accustomed to dry spells. Watering is only necessary when the soil has dried out and during prolonged hot and dry weather. If thyme is over-watered, its foliage turns yellow and wilts.

Thyme enjoys a light, sandy soil that is not too rich and, in most cases, using new compost like our Plantura Organic Herb & Seeding Compost when re-potting will provide all it needs to thrive. Feeding thyme plants is usually not necessary, however, if your plant appears weak or has very little new growth, apply a balanced liquid or seaweed fertiliser on a monthly basis. It is best to avoid over-feeding thyme as high levels of nutrients can cause leggy new growth and a loss of flavour.

Pruning thyme

Pruning thyme is not strictly necessary. However, once the summer flowers have faded, snip these off to promote new fresh growth and prevent the plant from using precious energy in setting seed. Over winter some growth may die back, prune this back along with any broken branches.

Harvesting the new foliage as needed and keeping the shape to a dome, will help promote new growth and keep the plant from growing leggy over time. Use a clean and sharp pair of scissors or secateurs to harvest thyme. You can pick thyme all year round, but it is most flavoursome in early summer. For more tips on how to harvest and store thyme see our other article.

Leaves turning yellow: what to do?

Thyme leaves turning yellow is a common problem and usually indicates that the plant is suffering from root rot. Growing thyme in a heavy soil with poor drainage or overwatering can cause root rot. If root rot is suspected, water less and if no improvement is seen try re-potting using a fresh free-draining compost mix with some added horticultural grit.

Overwintering thyme

Thyme is a hardy plant that can usually withstand our UK winter temperatures. However, thyme dislikes wet weather, especially in cold temperatures. Place pots on feet to aid drainage and under a porch or in the lee of a wall to shield them from the worst of the rain.

A benefit of growing thyme in pots is that they can easily be brought indoors to overwinter. If moving inside for winter, place the thyme on a windowsill so it can receive as much natural light as possible and reduce watering until spring. Harden off in spring before placing outdoors again to enjoy the summer months.

If learning about how to grow thyme has got you thinking about what other herbs you could grow and how, check out our article about planting herbs.