Thyme-leaved sandwort

How to recognise it

Growth form

Annual or winter annual, 5–25 cm, much branched from the base, sprawling to ascending; forms loose, grey-green tufts.

Leaf

Opposite, stalkless, oval and pointed, 3–7 mm, grey-green and finely hairy, slightly rough to the touch. Looks like a thyme leaf.

Flower

White, 5–8 mm across, with five undivided petals shorter than the five pointed sepals. Flowers from April to September.

Fruit/Seed

An egg-shaped to flask-shaped capsule that opens at the top with six teeth, full of tiny, dark brown, kidney-shaped seeds.

Stem

Thin, round, finely and shortly hairy and rather stiff; not juicy.

Confusion with

Common chickweed has deeply divided white petals, juicy stems with a single line of hairs and larger, pale green leaves. Three-nerved sandwort has larger, stalked leaves with three veins and grows in woodland. Slender sandwort, sometimes treated as a separate species, is even more delicate, with smaller flowers and narrow, straight-sided capsules.

Flowering: April–September

Why grow it?

• A pioneer of bare, dry ground: it covers open sand and gravel and helps hold it in place.
• The small flowers are visited by tiny flies, small hoverflies and other small insects, although it is not a major nectar source.
• The many tiny seeds are food for seed-eating insects and small seed-eating birds.
• A plant for a dry, sunny rockery, a gravel garden or the joints of a patio, where little else grows.
• Little work and not invasive: it stays small and is easy to remove where it is not wanted.

Thyme-leaved sandwort: where does it grow best?

• In the wild in dry, open, sunny places: sandy and chalky verges, fields, dunes, quarries, railway land, walls and cracks in paving.
• Full sun; in shade it soon disappears.
• Dry, poor, well-drained soil: sand, gravel, chalk or stony rubble. On rich, moist soil it gets overgrown.
• In the garden: in a gravel garden or rockery, on a dry wall or in the joints of a patio or path.

Goes well with

• Biting stonecrop: Yellow stars in the same dry, sunny spot, on sand and gravel.
• Sheep’s-bit: Blue pompons on poor sandy soil in summer.
• Harebell: Delicate blue bells on a dry, poor verge.
• Common stork’s-bill: Another small pioneer of open sandy ground, with little pink flowers.
• Hare’s-foot clover: Soft, grey-pink clover heads on dry sandy soil.

Thyme-leaved sandwort: when and how to plant it?

1. Usually thyme-leaved sandwort turns up by itself on bare, sunny ground. If you want to sow it, buy native seed from a specialist seed supplier.
2. Sow in September–October or in March–April on bare, dry soil, gravel or sand.
3. Scatter the fine seed thinly and press it down, but cover it hardly or not at all.
4. Keep the soil slightly moist only for the first few weeks after sowing; after that it needs no water.
5. Keep the spot open: no mulch, no compost and no tall plants around it.
6. Do not dig up plants in the wild; there is no need anyway, as it self-sows easily.

Care

Water

Not needed: it grows in dry places by nature.

Feeding

Never: on fertile soil it is crowded out by larger plants.

Weeding

Keep the spot open: pull out large, vigorous plants that shade it.

Spreading

No problem: it is small and easy to pull out by hand. In the joints of a path it does no harm.

Letting it seed

Let the plants ripen until the capsules open: that way it returns every year.

Tip: In a gravel path or on a patio, leave a strip of joints undisturbed: thyme-leaved sandwort, biting stonecrop and other small pioneers will appear there by themselves, and you will have a mini nature reserve with no work.

Pruning and mowing

When: Not needed: thyme-leaved sandwort is an annual and dies by itself after setting seed.

How:

• Leave the plants until they have dried up and the seed has fallen.
• Then clear away the dead plants, or simply leave them: they break down quickly.
• Do not mow or hoe while it is in flower if you want to keep it.

Pruning calendar and basic rules

Propagation

Seed

It self-sows. To move it elsewhere, shake ripe, dry plants over bare ground in summer, or sow collected seed in autumn.

Thyme-leaved sandwort: how does it get through the winter?

Hardy to −20 °C.

• Plants that germinate in autumn overwinter as small green tufts and flower early in spring.
• Hardy: the small plants tolerate severe frost.
• Seed in the soil survives the winter and germinates in spring.

Diseases and pests

• Overgrown: On soil that is too rich or among tall plants it disappears. Keep the spot poor and open.
• Unwanted in paths: If you would rather not have it in the joints, pull it out before the seed ripens or scrape the joints clean. Do not use weedkillers.
• Confusion when weeding: It looks like common chickweed, but is finer, greyer and rougher, and grows on poor, dry soil. Look carefully before you weed.
• Gone after a year: Normal for an annual: without bare ground to germinate in, it will not come back. Scratch the soil open a little in autumn.

Through the year

• March: Sow on bare, dry ground. Overwintered plants start growing again.
• April: First flowers on overwintered plants.
• May: Full flower; tiny flies on the flowers.
• June: Flowering and first ripe capsules.
• July: The seed ripens; let the plants ripen.
• August: Later seedlings flower. Leave dead plants where they are.
• September: Flowering comes to an end. Sow; new seedlings germinate.
• October: Sow. Young plants overwinter.

Did you know?

• Arenaria comes from the Latin arena, sand: the plant grows mainly in sandy places. Serpyllifolia means ‘with leaves like wild thyme’ (Thymus serpyllum).
• In Dutch, many small members of the pink family are called ‘muur’, such as this sandwort (zandmuur) and chickweed (vogelmuur). The name has nothing to do with a stone wall: it is related to the German ‘Miere’.
• The capsule opens at the top with six teeth; with a gust of wind or a knock, the seeds are shaken out as from a pepper pot.