Ornamental · Rubiaceae
Sweet Woodruff
Galium odoratum
A soft, sweet-smelling shade carpet that forgives beginners while the cool soil stays moist.
Full shade
Every 3–7 days
USDA 4–8
6–12 in · 15–30 cm
Overview
Sweet woodruff is a low groundcover that feels right at home in cool shade, filling the quiet corners where other plants sulk. It belongs to the Rubiaceae family, and you will notice its slim leaves arranged in neat whorls around square stems, with small white star-shaped flowers arriving in late spring. Brush against the foliage or let it dry, and it gives up a soft scent of fresh-cut hay, which is exactly why old herb gardens kept it close.
Offer it the dappled shade beneath trees or the shaded north side of a wall, and within a season it weaves itself into a soft, even carpet. It travels by creeping rhizomes and by seeding about, quick enough to blanket bare ground and, truth be told, quick enough to wander a little, so a bit of edging keeps it polite where space is tight. In hot, dry sun it can scorch and rest through the summer, but that is simply its way of coping.
This is one of the more relaxed plants you can grow, with no serious pests or diseases to speak of once it settles into the cool, moist, humus-rich soil it loves. The single thing to remember is the coumarin in its leaves, the very compound that makes it smell so sweet. A little goes into the traditional German May wine, but larger amounts simply are not safe to eat.
Care
The short version: give it cool, moist, humus-rich shade and a slightly acidic soil, and you are most of the way there. Water it through dry spells, feed it hardly ever, and tuck in some edging if you would rather it not wander. Mistakes here are easy to undo.
Light
Set it in full to partial shade, the gentle dappled light you find beneath trees. A touch of morning sun will not bother it, but hot, dry, full sun scorches the leaves and coaxes it into an early rest, so lean toward the shadier spot if you are unsure.
Water
Aim to keep the soil cool and evenly moist, watering about every 3 to 7 days when the weather turns dry. Once it has settled in, it can handle dry shade too, so do not panic if you miss a day; it simply stays greenest where the ground never bakes right through.
Soil
It is happiest in humus-rich, well-drained loam that leans a little acidic, around a pH of 5.0 to 6.5. Mix in some leaf mold or compost before planting and it will spread contentedly, no special treatment required.
Temperature
This is a tough, hardy little plant that shrugs off cold down to about -29°F (-34°C) and grows well up to roughly 84°F (29°C). Beyond that, in real dry heat, it may scorch and quietly wait for cooler days, then bounce back none the worse.
Humidity
Everyday outdoor humidity is all it needs, so there is no figure to worry over. In crowded, still plantings, fresh air matters more than the moisture in the air, since stagnant pockets can invite the occasional leaf spot.
Feeding
This one is a light feeder that seldom asks for much. A thin spring topdressing of compost or leaf mold does the whole job, and piling on more only encourages the spreading you are likely already managing.
Pruning
Pruning stays wonderfully simple. Once it finishes blooming, shear or mow it back to tidy any tattered or scorched foliage, refresh the mat, and gently hold its spread in check at the same time.
Repotting
If you are growing it in a container, plan to divide and repot it every 1 to 2 years as the rhizome mat fills the space. Roots circling the pot, a thinning middle, or a mat pushing at its edges are your friendly reminders that it is time.
Size & spacing
It keeps low, reaching just 6 to 12 inches (15 to 30 cm) tall while stretching out sideways. Each plant covers around 12 to 24 inches (30 to 60 cm), so space them about that far apart and let them gently grow together.
When to plant
Sweet woodruff keeps to the cool seasons, which makes its timing forgiving. Start seed in late winter to early spring after a cold spell, settle divisions into moist ground in spring or early fall, and watch for those little white flowers in late spring.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring; seed germinates slowly and benefits from cold stratification
- Plant: Spring or early fall in shade
- Harvest: White star-shaped flowers in late spring (April to May)
Hardiness
USDA hardiness zones: 4–8
Temperature: down to -34°C
Troubleshooting
Happily, sweet woodruff rarely gives you much to worry about, and nearly every hiccup traces back to where it is planted. Keep a kind eye on the edges for wandering and on the leaves for sun-scorch, and you will catch things early. Find your symptom below and make a small change before it grows into a big one.
Wandering past the spot you chose for it
Sweet woodruff moves around by creeping rhizomes and by seeding itself, and in the cool, moist shade it adores it can slip happily into the beds next door. There is an easy fix: slide in some edging or a root barrier before it hits its stride, and lift any stray runners by loosening the soil and easing them out whole, since the brittle stems snap if you tug. A trim after flowering keeps it from scattering even more seed.
Fix:
- Install a physical root barrier or plant in a contained bed or sunken edging
- Dig out unwanted rhizomes by loosening the soil and lifting them whole rather than pulling stems, which break easily
- Deadhead or shear after flowering to limit self-seeding
Browning, crisped leaves and a patch that is thinning out
When you see leaf scorch, it usually means the plant is sitting in hot, dry, sunny ground rather than the cool shade it longs for, and in a rough spell it may simply go semi-dormant for the summer. Gently move it into part to full shade, tuck mulch around it to keep the soil cool, and water it through the dry stretches. Trim the burnt foliage away, and fresh green growth returns once the heat lets up.
Fix:
- Move or establish plants in part to full shade
- Keep soil cool and evenly moist with mulch and supplemental water in dry spells
- Cut back scorched foliage to encourage fresh regrowth once conditions cool
Spotted leaves in a crowded, stuffy corner
Every so often a fungal leaf spot appears where the air stands still and the leaves stay wet for too long. The remedy is gentle: thin the crowded growth so a breeze can pass through, water down at the base instead of over the top, and pick off the marked leaves. Given a good spot, sweet woodruff really has no serious pests or diseases to trouble you.
Fix:
- Improve air circulation by thinning crowded growth
- Avoid overhead watering and water at soil level
- Remove and discard affected foliage
Toxicity
There is no need for alarm here, though sweet woodruff is not something to eat freely. Its leaves carry coumarin, the same compound behind that lovely sweet scent, and a small pinch to flavor May wine is perfectly traditional. Eaten in real quantity it can thin the blood, tire the liver, and bring on dizziness, so keep big helpings away from pets, livestock, and people, and you will all be fine.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Caution
A single nibble of the leaves is unlikely to cause any real trouble, but the coumarin they carry makes a big mouthful a poor idea. Keep a gentle watch for an upset tummy or a sleepy, sluggish cat if more than a leaf or two goes down.
Dogs Caution
The odd small mouthful usually passes without a fuss, though that same coumarin can thin the blood and tax the liver if a dog eats a lot. Steer them away from grazing a whole patch, and give the vet a call if a large amount disappears.
Horses Caution
A little mixed in with pasture is nothing to worry about, but a big feed of the coumarin-rich leaves can lead to bleeding troubles and leave a horse dull and off-color.
Rabbits Caution
A small browse is generally fine, yet the coumarin means it should not turn into a regular part of the diet. Offer just the occasional sprig rather than letting a rabbit make a meal of it.
Livestock Caution
Cattle, goats, and sheep can nibble a little without harm, but a heavy helping of the fresh or dried leaves raises the risk of internal bleeding and liver strain from the coumarin.
Birds Caution
Birds tend to pay it little mind, and a peck here and there is no cause for concern. The thing to gently avoid is steady, day-after-day feeding on the coumarin-bearing leaves.
People Caution
A small amount flavors May wine and teas quite safely, which is its cherished old kitchen use. Eat it by the handful, though, and the coumarin can bring liver damage, bleeding, and dizziness, so keep every helping small.
Foliage contains coumarin, the compound behind its sweet, fresh-cut-hay scent (which intensifies as it dries). In large quantities coumarin can have blood-thinning (anticoagulant) effects and cause liver issues, and the FDA prohibits coumarin as a food additive, so only small culinary amounts are traditionally used and large quantities should not be eaten.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
There is little to fuss over when choosing. Sweet woodruff is grown almost entirely as the simple species, so you can pick it with confidence and move on.
Galium odoratum (straight species)
Nearly everyone simply grows the plain species, since it comes with few named cultivars and was once listed under its older name, Asperula odorata.
How to propagate
Making more sweet woodruff is genuinely easy and hard to get wrong. Split a clump you already have, or simply let it seed itself around, and you will have new plants before long.
DivisionEasy
Spring (or any time in the growing season if kept moist until established) · A few weeks to a season
Division is the gentle, reliable way to make more. In spring, lift the rhizomatous clumps, ease them apart with your hands, and tuck the pieces back into moist shade, where they knit together again within a few weeks to a season.
SeedModerate
Late winter to early spring; benefits from cold stratification · One or more seasons; germination is slow
Left to itself, the plant self-seeds freely, but sowing it on purpose does test your patience a little. Scatter seed in late winter to early spring after a spell of cold stratification, and expect slow, uneven sprouting that can take a season or more to fill in, which is perfectly normal.
Myths
Since it flavors May wine, sweet woodruff must be completely edible in any amount.
It is only safe in small culinary pinches. The leaves hold coumarin, which in quantity can thin the blood and harm the liver, and the FDA does not allow coumarin as a food additive. Use a light hand when flavoring, and never sit down to a bowlful.