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Black Scallop Bugle (Carpet Bugle) care

Ajuga reptans 'Black Scallop'

Also called Black Scallop Bugle, Black Scallop Bugleweed, Carpet Bugle.

RHS H7USDA 3–9Mildly toxic to petsIndoor 15–20 cm tall in flower

Watering rhythm

Medium indirect light (a couple of metres from a window)

Once or twice weekly; reduce to once weekly when established

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Light

Medium indirect light (a couple of metres from a window)

Soil

Moist, well-draining loam; tolerates clay

Humidity

40–70%

Temp

-20°C to 30°C

Pet safety

Mildly toxic to pets

Mature size

15–20 cm tall in flower

Care at a glance

Light

The Goldilocks zone. Not the south-facing windowsill (too hot, too direct), not the back of the room (too dim, growth stalls). Best foliage colour — deepest near-black — develops in partial shade with 2–4 hours of dappled or morning sun. Full shade is tolerated but darkening of the leaf colour may be less pronounced. Intense afternoon sun bleaches foliage and stresses the plant. If you can't decide, a free phone lux-meter app aimed at the leaf at noon should read between 800 and 1,500 lux.

Watering

Watering black scallop bugle: once or twice weekly; reduce to once weekly when established. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Requires consistently moist soil during establishment. Once rooted, moderately drought-tolerant, but prolonged dry spells cause leaf scorch and dieback. Deep watering at the root zone is preferable to frequent shallow watering. Reduce in winter.

Soil and pot

Black Scallop Bugle grows best in moist, well-draining loam; tolerates clay. Thrives in average to fertile, moisture-retentive soil at pH 5.5–7.0. Tolerates heavier clay better than many groundcovers provided waterlogging is avoided. Incorporate organic matter at planting to improve structure. Very sandy soils need regular moisture supplementation. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Black Scallop Bugle sits happiest at around 40–70% humidity and -20°C to 30°C (-4°F to 86°F). Adapted to outdoor temperate humidity levels. Not sensitive to ambient humidity when planted in the ground. Mulching with bark or leaf mould helps maintain soil moisture during summer. In containers, monitor more closely in dry indoor conditions. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed black scallop bugle sparingly. A single application of balanced slow-release fertiliser in early spring is sufficient. Too much nitrogen leads to green-tinted foliage, diminishing the dark coloration that makes this cultivar desirable. Do not feed in late summer or autumn. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on black scallop bugle in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Crown rot — Wet, poorly ventilated conditions invite Phytophthora and Botrytis crown rot. Thin dense mats every 2–3 years, improve drainage, and avoid waterlogging. Remove and dispose of any blackened, mushy crowns immediately.
  • Foliage greening — In deep shade or with excess nitrogen, the near-black leaves may revert toward green, reducing ornamental value. Ensure at least some indirect light reaches the planting and avoid high-nitrogen feeds.
  • Slugs and snails — The dense, low foliage provides ideal shelter for slugs, which chew ragged holes in leaves. Apply iron phosphate pellets in spring and autumn, or use physical barriers such as copper tape in containers.

Propagation

Divide established clumps in spring or early autumn, separating rooted rosettes and replanting at 25–35 cm spacing. Individual stolons with rooted nodes can be detached and grown on. Does not reliably come true from seed. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Black Scallop Bugle is mildly toxic to pets. Ajuga reptans is not individually listed by the ASPCA, but iridoid glycosides present in the genus may cause mild gastrointestinal irritation in dogs and cats if consumed. Not considered severely toxic, but ingestion of large quantities should be avoided. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Black Scallop Bugle care — frequently asked questions

What is the common name for Ajuga reptans 'Black Scallop'?

Ajuga reptans 'Black Scallop' is most commonly called Black Scallop Bugle, but it is also known as Black Scallop Bugle, Black Scallop Bugleweed, Carpet Bugle. The names refer to the same species, so care instructions for Black Scallop Bugle apply identically to anything sold as Carpet Bugle.

How much light does black scallop bugle need?

Black Scallop Bugle grows best in medium indirect light (a couple of metres from a window). Best foliage colour — deepest near-black — develops in partial shade with 2–4 hours of dappled or morning sun. Full shade is tolerated but darkening of the leaf colour may be less pronounced. Intense afternoon sun bleaches foliage and stresses the plant.

How often should I water black scallop bugle?

Water black scallop bugle once or twice weekly; reduce to once weekly when established. Requires consistently moist soil during establishment. Once rooted, moderately drought-tolerant, but prolonged dry spells cause leaf scorch and dieback. Deep watering at the root zone is preferable to frequent shallow watering. Reduce in winter. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is black scallop bugle toxic to cats and dogs?

Black Scallop Bugle is mildly toxic to pets. Ajuga reptans is not individually listed by the ASPCA, but iridoid glycosides present in the genus may cause mild gastrointestinal irritation in dogs and cats if consumed. Not considered severely toxic, but ingestion of large quantities should be avoided.

What USDA hardiness zone does black scallop bugle grow in?

Black Scallop Bugle is rated for USDA zone 3–9 and RHS hardiness H7. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Black Scallop Bugle deep-dive guides

Every aspect of black scallop bugle care, each with its own calibrated guide:

Featured in these plant shortlists

Black Scallop Bugle qualifies for 6 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Black Scallop Bugle is also known as Black Scallop Bugle, Black Scallop Bugleweed, and Carpet Bugle.