Growli
Let's go

Plant care

Chrysanthemum 'Ruby Mound' (Ruby Mound mum) care

Chrysanthemum 'Ruby Mound'

Also called Ruby Mound mum, garden chrysanthemum, hardy mum.

RHS H5USDA 5-9Toxic to petsIndoor 35-45 cm tall and 40-50 cm wide

Watering rhythm

5-7days

When the top 2-3 cm of soil is dry, roughly every 5-7 days in the growing season

Jump to schedule→Get smart reminders in the app

Light

Direct sun (at least 4-6 hours)

Soil

Fertile, free-draining loam or enriched garden soil

Humidity

40-60%

Temp

5-24°C

Pet safety

Toxic to pets

Mature size

35-45 cm tall and 40-50 cm wide

Care at a glance

Light

Most houseplants will scorch where chrysanthemum 'ruby mound' thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Requires at least 6 hours of direct sun per day for compact growth and the best flower production. Insufficient light leads to leggy stems and reduced blooming. 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 2-3 cm of soil is dry, roughly every 5-7 days in the growing season for chrysanthemum 'ruby mound', 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 at the base to keep foliage dry and reduce fungal disease risk. Reduce watering in autumn as flowering finishes. Avoid waterlogged soil, especially in winter.

Soil and pot

Chrysanthemum 'Ruby Mound' grows best in fertile, free-draining loam or enriched garden soil. Amend heavy clay with grit or perlite to improve drainage. A slightly acid to neutral pH of 6.0–7.0 is ideal. Good drainage is critical to prevent crown rot over winter. 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

Chrysanthemum 'Ruby Mound' sits happiest at around 40-60% humidity and 5-24°C (41-75°F). Tolerates average outdoor humidity well. Good air circulation around the plant reduces powdery mildew risk, which is the main humidity-related problem for chrysanthemums. If you keep the room above 5 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 chrysanthemum 'ruby mound' sparingly. Apply a balanced granular fertiliser (e.g. 10-10-10) in spring when growth resumes, then switch to a low-nitrogen, high-potassium feed from midsummer to encourage flower bud formation rather than leafy growth. 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 chrysanthemum 'ruby mound' in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Aphids — Clusters on new shoot tips in spring; blast off with water or treat with insecticidal soap.
  • Powdery mildew — White coating on leaves in humid, still conditions; improve air flow and avoid overhead watering.
  • Leaf miners — Pale sinuous trails in leaf tissue; remove and destroy affected leaves promptly.
  • Crown rot — Caused by waterlogged winter soil; ensure sharp drainage and lift/divide congested clumps every 2-3 years.
  • Earwig damage — Ragged holes in petals and leaves overnight; trap in rolled damp newspaper placed near the plant.

Companion plants

Chrysanthemum 'Ruby Mound' pairs well with Sedum 'Autumn Joy', Rudbeckia fulgida, Echinacea purpurea, and Ornamental grasses. 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

Divide established clumps in spring every 2-3 years, replanting vigorous outer sections and discarding the woody centre. Basal cuttings taken in spring root readily in a free-draining propagation mix under gentle bottom heat. 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

Chrysanthemum 'Ruby Mound' is toxic to pets. Chrysanthemum species are listed by the ASPCA as toxic to dogs, cats, and horses. They contain pyrethrins, sesquiterpene lactones, and other compounds that can cause vomiting, diarrhoea, hypersalivation, incoordination, and dermatitis. 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.

Chrysanthemum 'Ruby Mound' care — frequently asked questions

What is the common name for Chrysanthemum 'Ruby Mound'?

Chrysanthemum 'Ruby Mound' is most commonly called Chrysanthemum 'Ruby Mound', but it is also known as Ruby Mound mum, garden chrysanthemum, hardy mum. The names refer to the same species, so care instructions for Chrysanthemum 'Ruby Mound' apply identically to anything sold as Ruby Mound mum.

How much light does chrysanthemum 'ruby mound' need?

Chrysanthemum 'Ruby Mound' grows best in direct sun (at least 4-6 hours). Requires at least 6 hours of direct sun per day for compact growth and the best flower production. Insufficient light leads to leggy stems and reduced blooming.

How often should I water chrysanthemum 'ruby mound'?

Water chrysanthemum 'ruby mound' when the top 2-3 cm of soil is dry, roughly every 5-7 days in the growing season. Water at the base to keep foliage dry and reduce fungal disease risk. Reduce watering in autumn as flowering finishes. Avoid waterlogged soil, especially 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 chrysanthemum 'ruby mound' toxic to cats and dogs?

Chrysanthemum 'Ruby Mound' is toxic to pets. Chrysanthemum species are listed by the ASPCA as toxic to dogs, cats, and horses. They contain pyrethrins, sesquiterpene lactones, and other compounds that can cause vomiting, diarrhoea, hypersalivation, incoordination, and dermatitis.

What USDA hardiness zone does chrysanthemum 'ruby mound' grow in?

Chrysanthemum 'Ruby Mound' 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.

Chrysanthemum 'Ruby Mound' deep-dive guides

Every aspect of chrysanthemum 'ruby mound' care, each with its own calibrated guide:

Featured in these plant shortlists

Chrysanthemum 'Ruby Mound' 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

Chrysanthemum 'Ruby Mound' is also known as Ruby Mound mum, garden chrysanthemum, and hardy mum.