How to Grow Thyme: A Practical Guide from Seed to Harvest

Thyme is one of those herbs that's worth getting established because, once it's growing well, it needs very little attention. It's a small plant, doesn't take up much room and will happily grow in a sunny border, raised bed or pot.

It's a perennial too, so you won't need to sow it again every year. An established plant can provide fresh leaves for years, and the little flowers are very popular with bees and other pollinating insects.

The main thing with thyme is not to be too kind to it. It likes sunshine and good drainage and will cope with dry conditions far better than sitting in cold, wet soil. Rich soil and lots of feeding aren't necessary either.

You can grow thyme from seed quite easily, although the seedlings are tiny and take a little patience at first. Once they're established, there's really not much to it.

Give thyme a sunny spot, don't overwater it and trim it occasionally to keep the plant compact.

When to Sow

Thyme can be sown from February to May, although March and April are probably the easiest months if you're starting plants under cover.

You can sow earlier if you have somewhere warm and bright, but thyme seedlings are very small and don't grow particularly quickly at first. There's little advantage in producing tiny seedlings in January that then have to struggle through weeks of poor light.

I usually prefer waiting until the days are getting longer.

Sow in pots or trays under cover and keep them somewhere reasonably warm while they germinate.

You can sow later in spring too. Thyme is a perennial, so don't worry if your plants aren't enormous by the end of their first summer. You're getting them established for future years rather than trying to produce everything in one season.

Once the seedlings are growing well, keep them somewhere bright and frost-free until conditions are suitable for planting outside.

How to Sow

Thyme seed is very small, so this is one of those sowing jobs where a little care helps.

Fill a small pot or seed tray with fine seed compost and gently firm the surface. Water the compost before sowing and allow any excess to drain away.

Sprinkle the seeds thinly over the surface.

Don't bury them deeply. Cover with a very light layer of compost or vermiculite, or simply press the seeds gently onto the surface.

Keep the compost moist while you're waiting for germination, but don't make it soaking wet.

Thyme can take a couple of weeks or longer to germinate, so don't be too quick to give up on the tray.

Once seedlings appear, give them plenty of light.

When they start to grow, they need light and a little water. After this its about being patient.

Growing Seedlings On

Once the seedlings are large enough to handle, carefully move them into small individual pots or modules.

You don't necessarily have to separate every tiny seedling. If several are growing together, you can pot on a small group and let them develop into a bushier plant.

Handle them gently because the seedlings are quite delicate at this stage.

Keep young plants somewhere bright and don't overwater them. As they become established, start allowing the surface of the compost to dry slightly between waterings.

If the plants fill their pots before it's time to plant outside, move them into something slightly larger.

Before planting out, harden them off gradually over a week or two. Plants raised in a greenhouse or indoors need a little time to get used to outdoor conditions.

Thyme isn't difficult once it's established. 

By late spring or early summer, you should have sturdy little plants ready to find a permanent home.

Planting Out and Spacing

Thyme likes a sunny position and well-drained soil.

If there's one thing I'd get right, it's the drainage. Thyme naturally prefers fairly dry conditions and doesn't enjoy sitting in wet ground, particularly through winter.

Ordinary garden soil is usually fine as long as it drains reasonably well. If you have heavy clay that stays wet, a raised bed or container may be a much better home.

There's no need to add lots of manure or fertiliser before planting.

Space plants around 20–30cm apart, depending on the variety and how large you want them to become.

Thyme is particularly good in pots. A container near the kitchen door gives you easy access for picking and makes it much easier to provide the free-draining conditions the plant likes.

Water young plants after planting and while they're getting established.

Once their roots have settled in, you can start being considerably less attentive with the watering can.

Growing On and Pruning

Established thyme doesn't need much looking after.

Keep weeds away from young plants until they've filled out, then mostly let them get on with it.

Thyme gradually develops woody stems as it gets older. A light trim once or twice during the growing season helps keep plants compact and encourages fresh leafy growth.

After flowering is a good time to give the plant a tidy.

I wouldn't cut an old plant hard back into bare woody stems. Like sage, thyme doesn't always respond particularly well if you remove all the green growth.

Trim back into leafy growth instead.

The small flowers are excellent for bees, so I like to let the plants flower before giving them a proper tidy.

If an old thyme plant becomes very woody, open and unproductive, replacing it with a younger plant is often easier than trying to renovate it completely.

Fortunately, once you've grown thyme successfully, you'll probably want another plant somewhere anyway.

Watering and Feeding

Thyme is much happier slightly dry than permanently wet.

Water young plants while they're establishing, but once they're settled into the ground they'll cope well with dry conditions.

During a prolonged drought, an occasional thorough watering is worthwhile, but there's no need to follow thyme around the garden with a watering can every evening.

Container plants need checking more regularly, particularly small pots during hot weather. Even then, let the compost begin to dry between waterings rather than keeping it constantly damp.

Feeding should be equally restrained.

Thyme growing in ordinary garden soil generally doesn't need additional fertiliser.

Plants in containers may appreciate a little feed during the growing season if they've been in the same compost for a long time, but don't overdo it.

Too much feeding can encourage softer growth and you really don't need it.

With thyme, sunshine and drainage are far more important than feeding. Give it those two things and an established plant will generally look after itself.

Harvesting

You can begin picking thyme once the plant is established and producing enough growth to spare.

Snip off young leafy shoots as you need them rather than stripping individual stems completely bare.

Regular light picking actually helps keep the plant bushy, so don't feel guilty about taking some for the kitchen.

The leaves can be harvested through much of the year. Growth is strongest from spring into summer, but established evergreen plants can often provide small amounts during winter too.

For drying, cut healthy leafy stems before or around flowering and hang small bunches somewhere warm, dry and airy. Once completely dry, strip the leaves from the stems and store them in an airtight container.

Don't take too much from a small first-year plant. Let it establish a decent framework first and you'll get far more from it in future.

One mature thyme plant can provide a surprising amount, particularly when you're only snipping a few sprigs at a time.

Common Problems

Plants Dying Over Winter

Wet soil is one of the biggest problems with thyme.

Established plants are reasonably hardy, but cold, waterlogged roots are a bad combination. If plants repeatedly struggle through winter, look at drainage before assuming the cold itself is responsible.

A raised bed or container can make a big difference on heavy soil.

Yellowing Leaves

Yellowing foliage can be a sign that the roots are staying too wet.

Check container drainage and avoid leaving pots sitting in saucers full of water. A few old leaves are nothing to worry about, but widespread yellowing deserves a closer look.

Plants Becoming Woody

Some woody growth is perfectly normal as thyme gets older.

Regular light trimming helps keep fresh growth coming from lower down the plant. Avoid cutting hard into completely bare old wood.

Eventually, very old plants may simply be better replaced.

Poor Growth

If thyme isn't growing well, check sunshine and drainage first.

A shady, damp corner isn't where thyme wants to be. Moving a container into more sunshine can sometimes make a surprisingly big difference.

Slugs and Snails

Young seedlings can occasionally be damaged by slugs and snails.

Keep an eye on them while they're small. Once thyme becomes established and develops its aromatic foliage, it generally has relatively few pest problems.

Spindly Growth

Plants grown with too little light can become thin and stretched.

Give thyme as much sunshine as possible and don't feed it heavily in an attempt to make it grow faster.

Thyme is another herb where doing less is often the right answer. Give it sunshine, good drainage and the occasional trim and it will usually get on perfectly well without you.