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Spiraea 'Anthony Waterer' (Anthony Waterer Spirea) care

Spiraea japonica 'Anthony Waterer'

Also called Anthony Waterer Spirea, Japanese Spirea 'Anthony Waterer'.

RHS H7USDA 3-9Mildly toxic to petsIndoor 90-120 cm tall and wide

Watering rhythm

7-10days

When the top 5 cm of soil is dry, roughly every 7-10 days during the growing season

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Light

Direct sun (at least 4-6 hours)

Soil

Fertile, moderately moist, well-drained loam

Humidity

40-70%

Temp

-25 to 38°C

Pet safety

Mildly toxic to pets

Mature size

90-120 cm tall and wide

Care at a glance

Light

Most houseplants will scorch where spiraea 'anthony waterer' thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Full sun (6+ hours) produces the richest flower colour and the most compact, well-branched habit. Tolerates partial shade but flowering is reduced. Avoid deep shade. A plant moved abruptly from low light to direct sun bleaches in 48 hours — always acclimatise over a week.

Watering

Aim for when the top 5 cm of soil is dry, roughly every 7-10 days during the growing season for spiraea 'anthony waterer', but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Water regularly during the establishment year. Mature plants are quite drought-tolerant once established. Consistent watering during dry summers extends the long flowering season.

Soil and pot

Spiraea 'Anthony Waterer' grows best in fertile, moderately moist, well-drained loam. Adapts to a wide pH range (5.0-7.5) and most soil types including clay-loam, provided drainage is adequate. Avoid very dry, shallow soils without amendment. 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

Spiraea 'Anthony Waterer' sits happiest at around 40-70% humidity and -25 to 38°C (-13 to 100°F). Outdoor ornamental; undemanding about humidity. Functions well across the range of temperate garden climates. 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 spiraea 'anthony waterer' sparingly. Apply a balanced granular fertiliser in early spring as growth resumes. Avoid excessive nitrogen, which produces rank lush growth with fewer flowers. Deadheading spent flowerheads and lightly trimming can encourage further flushes. 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 spiraea 'anthony waterer' in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Powdery mildew — A common late-season problem, especially in congested plantings with poor airflow. Apply a fungicide early or improve spacing and air circulation.
  • Aphids — Pink new spring growth is attractive to aphids. Treat early with insecticidal soap before populations build up.
  • Spider mites — Stippled, dull foliage with fine webbing in hot dry weather indicates spider mites. Mist the foliage; treat with an appropriate miticide if necessary.
  • Reverting to all-green growth — If variegated-leaved shoots appear (this cultivar has occasional variegated sports), remove all-green reverted growth promptly to maintain consistency.
  • Reduced flowering — Usually caused by over-shading or incorrect pruning. This is a summer bloomer flowering on new growth — hard prune in early spring to stimulate vigorous new flowering shoots.

Companion plants

Spiraea 'Anthony Waterer' pairs well with Lavandula angustifolia, Salvia nemorosa, Geranium 'Rozanne', and Achillea millefolium 'Cerise Queen'. These are species with similar light and water needs, so you can group them in the same room or on the same shelf and water as a batch.

Propagation

Propagate by softwood cuttings in early summer or semi-ripe cuttings in late summer. Division of established clumps in early spring or autumn is also effective for named cultivars. 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

Spiraea 'Anthony Waterer' is mildly toxic to pets. Spiraea japonica 'Anthony Waterer' is not individually listed by the ASPCA. The genus lacks a formal non-toxic clearance; mild gastrointestinal upset in pets following ingestion of plant material is possible, warranting a precautionary mildly-toxic classification. 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.

Spiraea 'Anthony Waterer' care — frequently asked questions

What is the common name for Spiraea japonica 'Anthony Waterer'?

Spiraea japonica 'Anthony Waterer' is most commonly called Spiraea 'Anthony Waterer', but it is also known as Anthony Waterer Spirea, Japanese Spirea 'Anthony Waterer'. The names refer to the same species, so care instructions for Spiraea 'Anthony Waterer' apply identically to anything sold as Anthony Waterer Spirea.

How much light does spiraea 'anthony waterer' need?

Spiraea 'Anthony Waterer' grows best in direct sun (at least 4-6 hours). Full sun (6+ hours) produces the richest flower colour and the most compact, well-branched habit. Tolerates partial shade but flowering is reduced. Avoid deep shade.

How often should I water spiraea 'anthony waterer'?

Water spiraea 'anthony waterer' when the top 5 cm of soil is dry, roughly every 7-10 days during the growing season. Water regularly during the establishment year. Mature plants are quite drought-tolerant once established. Consistent watering during dry summers extends the long flowering season. 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 spiraea 'anthony waterer' toxic to cats and dogs?

Spiraea 'Anthony Waterer' is mildly toxic to pets. Spiraea japonica 'Anthony Waterer' is not individually listed by the ASPCA. The genus lacks a formal non-toxic clearance; mild gastrointestinal upset in pets following ingestion of plant material is possible, warranting a precautionary mildly-toxic classification.

What USDA hardiness zone does spiraea 'anthony waterer' grow in?

Spiraea 'Anthony Waterer' 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.

Spiraea 'Anthony Waterer' deep-dive guides

Every aspect of spiraea 'anthony waterer' care, each with its own calibrated guide:

Featured in these plant shortlists

Spiraea 'Anthony Waterer' qualifies for 4 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Spiraea 'Anthony Waterer' is also commonly called Anthony Waterer Spirea or Japanese Spirea 'Anthony Waterer'.