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Plant care

Diana Rose of Sharon (Shrub Althaea) care

Hibiscus syriacus 'Diana'

Also called Diana Rose of Sharon, Shrub Althaea, Hardy Hibiscus 'Diana'.

RHS H5USDA 5-9Pet-safeIndoor 2-3 m tall

Watering rhythm

7-10days

When the top 5 cm of soil is dry, roughly every 7-10 days in summer

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Light

Direct sun (at least 4-6 hours)

Soil

Well-drained, fertile loam

Humidity

40-70%

Temp

-15 to 38°C

Pet safety

Pet-safe

Mature size

2-3 m tall

Care at a glance

Light

Aim for at least 4-6 hours of direct sun on the leaves. Requires full sun for the best flowering; at least 6 hours of direct sun daily. In partial shade the plant grows well but produces fewer, smaller flowers. If your only bright window faces south, that's perfect for diana rose of sharon — same window any aroid would fry on.

Watering

Watering diana rose of sharon: when the top 5 cm of soil is dry, roughly every 7-10 days in summer. 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. Keep consistently moist during the growing season, especially when buds are forming. Reduce irrigation after leaf drop in autumn. Established plants tolerate short dry spells.

Soil and pot

Diana Rose of Sharon grows best in well-drained, fertile loam. Thrives in a range of soils with good drainage; tolerates clay if not waterlogged. A neutral to slightly alkaline pH of 6.0–7.5 is ideal. Incorporate compost at planting to improve nutrient retention. 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

Diana Rose of Sharon sits happiest at around 40-70% humidity and -15 to 38°C (5 to 100°F). Adapts to most outdoor humidity levels. Adequate spacing between plants ensures air movement and reduces leaf disease. Avoid overhead watering to prevent fungal spots. 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 diana rose of sharon sparingly. Feed with a balanced fertiliser in early spring and again in midsummer. A phosphorus-rich formula supports flower bud development; avoid excess nitrogen which promotes leafy growth over blooms. 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 diana rose of sharon in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Japanese beetles — Feed on flowers and foliage in mid-summer in the US; hand-pick in early morning or use neem oil as a deterrent.
  • Aphids and whitefly — Common on new growth; treat with insecticidal soap and encourage beneficial insects.
  • Leaf spot — Brown or yellow spots caused by fungal pathogens; remove affected leaves and avoid overhead irrigation.
  • Late leaf out — Hibiscus syriacus is one of the last shrubs to leaf up in spring — do not assume it is dead; wait until late spring before taking action.

Companion plants

Diana Rose of Sharon pairs well with Buddleja davidii, Caryopteris x clandonensis, Perovskia atriplicifolia, and Hydrangea paniculata. 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

Take semi-ripe cuttings in mid to late summer and root in a heated propagator. Can also be grown from seed sown in spring with gentle heat, though named cultivars may not 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

Diana Rose of Sharon is pet-safe. The ASPCA lists Hibiscus syriacus (Rose of Sharon) as non-toxic to dogs and cats. Note that very large quantities of any plant material can cause mild gastrointestinal upset; the species is not considered a toxicity risk. 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.

Diana Rose of Sharon care — frequently asked questions

What is the common name for Hibiscus syriacus 'Diana'?

Hibiscus syriacus 'Diana' is most commonly called Diana Rose of Sharon, but it is also known as Diana Rose of Sharon, Shrub Althaea, Hardy Hibiscus 'Diana'. The names refer to the same species, so care instructions for Diana Rose of Sharon apply identically to anything sold as Shrub Althaea.

How much light does diana rose of sharon need?

Diana Rose of Sharon grows best in direct sun (at least 4-6 hours). Requires full sun for the best flowering; at least 6 hours of direct sun daily. In partial shade the plant grows well but produces fewer, smaller flowers.

How often should I water diana rose of sharon?

Water diana rose of sharon when the top 5 cm of soil is dry, roughly every 7-10 days in summer. Keep consistently moist during the growing season, especially when buds are forming. Reduce irrigation after leaf drop in autumn. Established plants tolerate short dry spells. 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 diana rose of sharon toxic to cats and dogs?

Diana Rose of Sharon is pet-safe. The ASPCA lists Hibiscus syriacus (Rose of Sharon) as non-toxic to dogs and cats. Note that very large quantities of any plant material can cause mild gastrointestinal upset; the species is not considered a toxicity risk.

What USDA hardiness zone does diana rose of sharon grow in?

Diana Rose of Sharon is rated for USDA zone 5-9 and RHS hardiness H5. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Diana Rose of Sharon deep-dive guides

Every aspect of diana rose of sharon care, each with its own calibrated guide:

Featured in these plant shortlists

Diana Rose of Sharon qualifies for 10 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

  • Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
  • Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
  • Best pet-safe flowering plants — Flowering houseplants the ASPCA lists as non-toxic to cats and dogs — colour and blooms in a pet home, without the worry.
  • Best pet-safe plants for bright light — Non-toxic to cats and dogs and happy in a bright, sunny spot — safe plants for your best-lit windowsill.
  • Best pet-safe large indoor plants — Big, floor-standing houseplants the ASPCA lists as non-toxic to cats and dogs — a statement plant that is safe around pets.
  • Best houseplants for full sun — Houseplants that want direct sun — the species for a hot south or west-facing windowsill where shade-lovers scorch.
  • Best houseplants for a cool room — Houseplants that tolerate cool conditions down to about 10°C — for an unheated spare room, hallway, porch or a home kept cool.
  • Best fast-growing houseplants — Houseplants documented as fast or vigorous growers — quick to fill a pot, cover a pole or trail down a shelf.
  • Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
  • Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
  • Browse all 30 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Diana Rose of Sharon is also known as Diana Rose of Sharon, Shrub Althaea, and Hardy Hibiscus 'Diana'.