Sweet Woodruff: So Much More Than a Groundcover!

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Sweet woodruff is attractive, fast-growing and so easy to grow … and that’s only the beginning! Photo: vanberkumnurserycom

Sweet Woodruff

Botanical name: Galium odoratum, syn. Asperula odorata
Common names: sweet woodruff, sweet-scented bedstraw, fragrant bedstraw, wild baby’s breath, master of the woods
Family: Rubiaceae
Height: 6 to 8 inches (15–20 cm), occasionally 1 foot (30 cm)
Spread: almost unlimited
Spacing for Groundcover Use: 10 inches (25 cm)
Exposure: partial shade, shade; sun in cooler summer areas
Soil: any soil acid to alkaline, preferably moist
Flowering: May, June
Foot Traffic: intolerant
Hardiness Zones: USDA zones 2 to 8, AgCan zones 3 to 8

Clump of sweet woodruff with white flowers and green leaves.
Sweet woodruff blooms breach two seasons: spring and summer. Photo: Hajotthu, Wikimedia Commons

One of my favorite ground covers is sweet woodruff. I just love the way it forms a nice uniform carpet even in the most shaded areas and stays green until the snow hits. And that sprinkling of tiny white flowers is just sublime.

However, its use as an ornamental ground cover remains relatively recent. Previous generations knew it better as a culinary and medicinal herb. Even in my local garden center, it’s still sold in the herb section … much, I’m sure, to the surprise of many gardeners who would have no idea of how to use it for herbal purposes.

Map of the distribution of sweet woodruff across Europe and Asia.
This map shows the various countries where sweet woodruff grows naturally. Ill.: plantsoftheworldonline.org

Origin: Sweet woodruff is a small herbaceous perennial found in shady or humid environments throughout temperate Eurasia from Spain and Ireland to Japan, and also Algeria. It has sometimes escaped from culture in the United States and Canada, although only very locally.

The botanical name Galium odoratum comes from the Greek gala (milk), as certain species of bedstraw were once used to curdle milk, while odoratum, from Latin, obviously refers its attractive yet rather unusual scent: the leaves, stems and rhizomes smell of freshly mown hay. The flowers do as well, but to a lesser degree. That’s because they’re rich in coumarin, an aromatic organic chemical compound.

Despite the “sweet” in its name, the plant is not strikingly fragrant … well, at least not in the garden. It’s when it has been dried that it best emits its pleasant fragance.

As for the origin of its numerous common names, woodruff refers to the plant’s habit of growing in woodlands as well as its whorls of leaves that look rather like ruffs (pleated collars). As for bedstraw, the dried leaves (straw) were once used to stuff pillows and mattresses (beds) where they offered not often comfort and a pleasant scent, but were believed to repel lice and bedbugs.

Botanical illustration of sweet woodruff showing various plant parts.
Each stem bears several whorls of narrow leaves and, in season, a small terminal bouquet of white flowers. Plants are linked together by creeping rhizomes. Ill.: Flora Batava, Wikimedia Commons

Description: Sweet woodruff is actually a very simple little plant. Each consists of an erect stem, several tiers of dark green, narrow leaves placed in a whorl (attached to the stem like the spokes of a wheel) and, in late spring or early summer, depending on the local climate, a cluster of small white 4-petaled flowers.

At least that’s what you see above the ground. Below, it reaches out to a whole colony of other plants through a series of thin rhizomes running horizontally just below the surface and it’s these rhizomes that produce this dense groundcover effect that has come to be its main ornamental feature.

Green carpet of sweet woodruff after blooming.
Even without flowers, the sweet woodruff makes a very attractive green carpet. littleprinceplants.com

The plant makes a very dense and very even groundcover … and a very attractive one, too. In fact, you really have to grow this plant en masse to appreciate its appearance: even without flowers, a carpet of sweet woodruffs is absolutely charming.

The foliage is semi-evergreen: in mild climates, it may persist all winter. In cold climates, it remains fully green until a seriously hard frost or the first snowfall, then dies back. It greens up quite quickly in the spring.

💰 Money-Saving Tip

Pot of sweet woodruff for sale, showing green leaves and many stems.
Each pot actually contains many plants you could separate and replant. Photo: littleprinceplants.com

Since every stem already has a root system and even a small pot of sweet woodruff will normally have at least six or seven stems, you already have enough plants to start a little colony! Divide them at planting time and save big on the purchase cost!

Cultivation: Prefer a semi-shaded to shaded location, with preferably rich and fairly moist soil. That said, it seems perfectly adapted to the dry shade caused by shallow tree roots. It will, though, object to severe drought, especially when planted in full sun. Under arid conditions, it tends to go summer dormant and turn yellow, so is not a good choice. It can, though, be grown in full sun in areas with relatively cool summers or spots where the soil stays evenly moist. 

This plant is much hardier than it’s often given credit for being. Many otherwise serious gardening sites suggest USDA hardiness zones 5 to 8, yet it seems perfectly fine in zone 2 (AgCan Zone 3). In fact, it seems to need a cool to cold winter to thrive and won’t be happy in outside of temperate regions.

Sweet woodruff in bloom filling in between stones.
Sweet woodruff easily and quickly fills the spaces between stones and pavers. Photo: paramountnursery.ca

Do be forewarned that this plant really is a groundcover, with the accent on the word cover: given a chance, it will spread quite fast. That’s interesting when you first plant it, as it fills in at a rapid rate, but it may not stop where you had planned. It can easily push out from the original planting at a rate of up to 18 inches (45 cm) a year, at least where conditions are to its liking. 

Make sure you control it with a barrier of some sort to keep it under control. Even simple lawn edging will suffice: just make sure you allowing the top of the barrier to protrude about 1 inch (2.5 cm) above the soil so it can’t creep over top.

If you ever plant it without a barrier and it “jumps the fence”, you’ll discover it’s actually fairly easy to control. It’s simple to pull out or hoe into submission and will be killed outright if you cut it to the ground in early summer. Intolerant of low mowing, it rarely invades lawns. 

However, it also doesn’t tolerate foot traffic. Like, don’t walk on it at all if you can help doing so. You can plant it between stepping stones as long as you keep to the pavers, but you certainly can’t walk on it regularly. 

Other than watering in times of drought, this plant needs no maintenance, not even fertilizing.

Whorl of sweet woodruff leaves.
If you weren’t sure what a whorl of leaves was, take a gander! Photo: needpix.com

Harvesting: For culinary, aromatic or medicinal purposes, harvest sweet woodruff during or just before flowering, when its somewhat bitter flavor and its aroma are at their most intense. Don’t cut whole swathes to the ground, though, as that will impede the groundcover’s ability to photosynthesize and recover, leaving bare patches. Instead, pick only of one stem out of 4 or 5. That will be hardly noticeable and besides, neighboring plants will soon fill in the gap with new plants from rhizomes.

Sweet woodruff is used both fresh and dried, but tends to turn black under humid conditions. So, dry it rapidly. To do so, tie stems it into small bunches and hang them upside down indoors in a dark, cool, dry spot with good air circulation so they can dry without delay.

Propagation: Usually done by division in spring or fall, or by stem cuttings after flowering. Also, by seed which germinates without any special treatment. Interestingly, the seeds bear tiny hooks and are spread by sticking to the fur of animals.

Horticultural Uses: Sweet woodruff is an excellent groundcover for forest and shaded environments, growing especially well in the dry shade at the base of deciduous trees. You may, however, find it too invasive for very orderly flower beds.

Medicinal Uses: The pleasant “freshly cut hay” scent of sweet woodruff comes, as mentioned above, from coumarin which has several medicinal properties, used among others in antispasmodic, cardiac, diuretic and sedative treatments. The plant is also slightly toxic (as are most medicinal plants) and should only be used at low doses. Avoid use entirely during pregnancy and lactation. 

Two glasses of Maitrank (pale yellow) with orange slices and sweet woodruff stems in bloom.
Glasses of Maitrank in Belgium. Skal! Photo: ridremont.be

Culinary uses: Sweet woodruff can be used fresh or dried to flavor cakes, cookies, jellies and also drinks, both alcoholic and not. Among others, it’s used to produce Maitrank, a popular aperitif in Germany and parts of Belgium and Luxembourg. The name means “May drink” for the month it which it’s produced and is prepared by macerating the flowering stems in white wine.

Other Uses: As mentioned above, sweet woodruff was once used to stuff pillows and mattresses and was also a strewing herb, that is, it was spread over dirt floors to hide unpleasant odors. Today, it is still used to aromatize potpourris and sachets and as a moth deterrent.

Sweet woodruff in bloom filling in around 2 hostas.
Bedstraw nicely fills the spaces between all but the shortest perennials and shrubs without hampering their growth. Photo: Paul2032, garden.org

Plant Groupings: Sweet woodruff is a superb ground cover for use with early spring bulbs, such as Siberian squills (Scilla siberica) and crocuses (Crocus spp.), as it begins to grow back just as their flowering ends, hiding their yellowing foliage from sight. It also works well as a living mulch around medium to tall perennials and shrubs, surrounding them with an attractive green carpet, but can shade out lower-growing varieties. It also offers a charming green carpet effect to park woodlands and is unharmed by moderate accumulations of fall leaves. In fact, they tend to work their way to the base of the plants and disappear from sight. 

💡Helpful Hint: Sweet woodruff seems to grow well under walnut trees (Juglans spp.), known to be hostile to many other plants.

Problems: No serious insect or disease problems. Its fragrance, which we find pleasant, is in fact a natural insect repellant. Also, herbivorous mammals, such as deer, hares and rabbits, don’t seem to bother it either. Chicken, though, apparently love it and need to be kept out of the sweet woodruff patch.

Other Galiums: The cosmopolitan genus Galium (most species are called bedstraws) includes more than 700 different species … but unfortunately many are weeds!

Where to Find Sweet Woodruff? In season, almost all garden centers carry it, at least in areas where it grows well. Many mail order nurseries that specialize in perennials, groundcovers or herb also offer it. 

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Sweet woodruff: yet another living tool for low maintenance landscaping!

Groundcovers for Sun

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Variety of thymes creating a multicolored groundcover.

Looking for a groundcover for a sunny spot? Maybe because the lawn isn’t holding up well or because it’s on a slope or is otherwise hard to mow… or simply because you really don’t want to mow anymore? Here is a list of plants you might find suitable:

  1. ‘Angelina’ Sedum (Sedum rupestre ‘Angelina’), zone 3, FTR: none
  2. Barren strawberry (Waldsteinia spp.), zone 4, FTR: poor
  3. Barrenwort (Epimedium x rubrum), zone 3, FTR: none
  4. Basket-of-gold (Aurinia saxatilis, syn. Alyssum saxtile), zone 3, FTR: none
  5. Bearberry (Arctostaphylos uva-ursi), zone 2, FTR: moderate20170426WEN.jpg
  6. Bearberry cotoneaster (Cotoneaster dammeri), zone 5b, FTR: none
  7. Bergenia (Bergenia crassifolia, syn. B. cordifolia), zone 2, FTR: none
  8. Bigroot geranium (Geranium macrorrhizum), zone 3, FTR: none
  9. Bird’s foot trefoil (Lotus corniculatus ‘Pleniflorus’, syn. ‘Plenus’, zone 3, FTR: good
  10. Bishop’s weed (Aegopodium podagraria ‘Variegatum’), zone 3, FTR: poor
  11. Black mondo grass (Ophiopogon plansicapus ‘Nigrescens’), zone 7, FTR: none

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    Bleeding-heart (Dicentra formosa). Photo: J Brew, Flickr

  12. Bleeding-heart (Dicentra formosa and D. eximia), zone 3, FTR: none
  13. Brass buttons (Leptinella squalida ‘Platt’s Black’), zone 4, FTR: good
  14. Bugleweed (Ajuga reptans), zone 3, FTR: moderate
  15. Cambridge geranium (Geranium x cantabrigiense), zone 3, FTR: none
  16. Caucasian Sedum (Sedum spurium), zone 3, FTR: none
  17. Creeping juniper (Juniperus horizontalis), zone 2, FTR: poor
  18. Creeping speedwell (Veronica repens), zone 2, FTR: moderate
  19. Creeping thyme (Thymus serpyllum), zone 3, FTR: moderate
  20. Crested iris (Iris cristata), zone 3, FTR: none
  21. Crownvetch (Coronilla varia), zone 4, FTR: none
  22. Cutleaf stephanandra (Stephanandra incisa ‘Crispa’), zone 3b, FTR: none
  23. Dwarf knotweed (Persicaria affinis, syn. Polygonum affine), zone 3, FTR: moderate

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    Faassen’s catnip (Nepeta faassenii). Photo: Wouter Hagens, Wikimedia Commons

  24. Faassen’s catnip (Nepeta x faassenii), zone 3, FTR: none
  25. Foamflower (Tiarella cordifolia), zone 3, FTR: none
  26. Goldenstar (Chrysogonum virginianum), zone 4, FTR: poor
  27. Green carpet (Herniaria glabra), zone 4, FTR: good
  28. Hairy greenweed (Genista pilosa), zone 5, FTR: poor
  29. Heuchera (Heuchera cvs), zone 3, FTR: none
  30. Hosta (Hosta cvs), zone 3, FTR: none
  31. Houseleek (Sempervivum spp.), zone 3, FTR: none
  32. Iceplant (Delosperma cooperi), zone 5b, FTR: poor
  33. Ivy (Hedera helix and others), zone varies according to species and cultivar: 4-9, FTR: poor

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    Kamchatka sedum (Sedum kamtschaticum ‘Weihenstephaner Gold’). Photo Maja Dumas, Wikimedia Commons

  34. Kamchatka sedum (Sedum kamtschaticum), zone 3, FTR: none
  35. Labrador violet (Viola riviniana ‘Purpurea’, syn. V. labradorica), zone 4, FTR: none
  36. Lady’s mantle (Alchemilla mollis), zone 3, FTR: none
  37. Lamb’s-ears (Stachys byzantina ‘Silver Carpet’), zone 3, FTR: none
  38. Lily-of-the-valley (Convallaria majalis), zone 3, FTR: none
  39. Liriope (Liriope muscari), zone 6 ou 7, FTR: none

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    Golden moneywort (Lysimachia nummularia ‘Aurea’). Photo: European Environment Agency

  40. Moneywort (Lysimachia nummularia), zone 3, FTR: moderate
  41. Moss phlox (Phlox subulata), zone 2, FTR: none
  42. New Zealand burr (Acaena microphylla), zone 4b, FTR: poor
  43. Oregano (Origanum vulgare), zone 4, FTR: none
  44. Ornamental strawberry (Fragaria x rosea), zone 3, FTR: moderate
  45. Pachysandra (Pachysandra terminalis), zone 4, FTR: none
  46. Perennial dusty miller (Artemisia stelleriana ‘Boughton Silver’, syn. ‘Silver Brocade’), zone 3, FTR: none
  47. Periwinkle (Vinca minor), zone 2b, FTR: moderate
  48. Rozanne™ geranium (Geranium ‘Gerwat’), zone 4, FTR: none
  49. Scotch moss (Sagina subulata glabrata ‘Aurea’), zone 3, FTR: moderate
  50. Self-heal (Prunella grandiflora), zone 4, FTR: none
  51. Sensitive fern (Onoclea sensibilis), zone 3, FTR: none

    20170426B Crusier, WC.jpg

    Siberian cypress (Microbiota decussata) forms a dense, weed-resistant groundcover. Photo: Crusier, Wikimedia Commons

  52. Siberian cypress (Microbiota decussata), zone 3, FTR: none
  53. Snow-in-summer (Cerastium tomentosum), zone 2, FTR: poor
  54. Spotted dead-nettle (Lamium maculatum), zone 2, FTR: none
  55. St. John’s wort (Hypericum calycinum), zone 6, FTR: none
  56. Sweet woodruff (Galium odoratum), zone 3, FTR: none
  57. Sweetfern (Comptonia peregrina), zone 2, FTR: none
  58. White clover (Trifolium repens), zone 3, FTR: moderate
  59. Wintercreeper (Euonymus fortunei), zone 5b, FTR: moderate

    20170426H Ghislain118 (AD), www.fleurs-des-montagnes.net

    Woolly thyme (Thymus pseudolanuginosus) Ghislain118 (AD), http://www.fleurs-des-montagnes.net

  60. Woolly thyme (Thymus pseudolanuginosus), zone 3, FTR: moderate
  61. Yellow archangel (Lamium galeobdolon), zone 2, FTR: none

Keeping Them Under Control

Most groundcover plants are a bit to very invasive… and that’s normal, considering that we choose groundcovers specifically for their ability to cover ground. It does, however, mean that you should always plan on how you eventually intend to slow them down when they’ve filled up their allotted space and start looking for new territory. You could, for example, contain them with a walkway, paving stones, a short wall, logs, lawn edging or deep shade.

Groundcovers for Shade

If you are looking for suggestions of shade-tolerant groundcovers, see the article Groundcovers for Shade.20170426A

Common Herbs With Weedy Ways

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Don’t let weedy herbs run amok in your garden! Illustration: confessionsofacomposter .blogspot.com

Who doesn’t enjoy fresh herbs, those aromatic plants that add such punch to our meals? Or treat our sniffles or upset stomaches? And they’re never fresher than when we grow them ourselves. That’s why herbs are presently so popular: everyone wants to try them. And most people find them easy to grow… at first. But many herbs have a major downside: they’re moderately to highly invasive and can quickly switch from being useful plants to becoming out-and-out garden thugs.

Two Categories of Weedy Herbs

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Borage is an easy-to-grow annual herb… perhaps too easy to grow, as it can self-sow so abundantly that it becomes a weed. Photo: Wikimedia Commons

There are two categories of potentially weedy herbs: those that produce creeping rhizomes or stolons (or sprout from broken pieces of root) that head off in all directions, soon producing offsets that surround and overwhelm neighboring plants, and those whose invasive habits are due to self-sowing, giving hordes of babies from the seeds they drop, hordes that can quickly threaten your entire herb garden.

Here is a list of the “main culprits” along with their preferred mode of invasion:

  1. Borage (Borago officinalis): seeds
  2. Caraway (Carum carvi): seeds
  3. Catnip (Nepeta cataria): seeds
  4. Chamomile (Matricaria recutita): seeds
  5. Chervil (Cerefolium anthriscus): seeds
  6. Chives (Allium schoenoprasum): seeds

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    Perilla or shish is a popular Chinese herb, but self-sows like the dickens. Photo: User:SB_Johnny, Wikimedia Commons

  7. Comfrey (Symphytum officinale): seeds and root sections
  8. Coriander or cilantro (Coriandrum sativum): seeds
  9. Costmary (Tanacetum balsamita): seeds
  10. Dill (Anethum graveolens): seeds
  11. Fennel (Foeniculum vulgare): seeds
  12. Feverfew (Tanacetum parthenium): seeds
  13. Garlic chives (Allium tuberosum): seeds
  14. Horseradish (Armoracia rusticana): root sections
  15. Lemon balm (Melissa officinalis): seeds
  16. Mint (Mentha spp.): stolons and creeping stems
  17. Monarde (Monarda didyma): rhizomes
  18. Mustard (Brassica nigra and B. juncea): seeds
  19. Origan (Origanum vulgare): seeds

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    Russian tarragon (Artemisia dracunculoides) can become a garden weed. Photo: Cillas, Wikimedia Commons

  20. Russian tarragon (Artemisia dracunculus): rhizomes and seeds
  21. Shisho or perilla (Perilla frutescens): seeds
  22. Sweet cicely (Myrrhis odorata): seeds
  23. Sweet woodruff (Galium odoratum): rhizomes
  24. Tansy (Tanacetum vulgare): rhizomes and seeds
  25. Thyme (Thymus vulgaris): seeds
  26. Valerian (Valeriana officinalis): seeds

How to Control Weedy Herbs

Weedy or not, several of the herbs presented above are essential to any herb garden. Can you even imagine cooking without thyme, oregano or chives? But fortunately there are ways to grow weedy herbs while limiting their ability to invade. Here are a few:

A. Self-Sowing Herbs

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Harvesting early and often prevents the plant from going to seed. Photo: Veganbaking.net, Wikimedia Commons.

  • Either remove all their flowers or harvest them before any seeds ripen;
  • Apply 3 to 4 inches (7 to 10 cm) of your choice of organic mulch (shredded leaves, wood chips, forestry mulch, etc.) throughout the herb garden, completely covering the soil. Seeds will not germinate in mulch-covered soil;
  • Hand pull when plants are still small;
  • Grow them beyond their hardiness zone. For example, fennel is hardy from zone 6 to 9 and can be weedy there if you let it go to seed. However, it won’t be invasive in zones 1 to 5.

B. Herbs With Wandering Rhizomes and Stolons

  • Cultivate them in pots on a deck, patio or balcony: that will nip any spread in the bud;

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    Peppermint (Mentha piperita) grow inside a barrier made of sunken pots.

  • Plant them inside a barrier sunk into the ground. This could simply be a plastic pot or pail with its bottom removed. The barrier should stick up at least 2 inches (5 cm) above the ground as the rhizomes of some plants, such as mint, right will creep right over a barrier that is level with the ground.

 


Don’t hesitate to grow herbs: most are great and very productive plants and you’ll be thrilled with the results. But do take note of the invasive ones. After all, forewarned is forearmed!20170425G confessionsofocomposter.blogspot.com