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Plant care

Poker alumroot (Roundleaf alumroot) care

Heuchera cylindrica

Also called Poker alumroot, Roundleaf alumroot, Lava coral bells.

RHS H7USDA 3–8Pet-safeIndoor 20–35 cm tall (flower spikes to 60 cm)

Watering rhythm

7-14days

Every 7–14 days once established; more frequent when young

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Light

Bright indirect light (just back from a sunny window)

Soil

Gritty, sharply draining rocky or sandy loam

Humidity

30–55%

Temp

−29 °C to 38 °C

Pet safety

Pet-safe

Mature size

20–35 cm tall (flower spikes to 60 cm)

Care at a glance

Light

Poker alumroot is what florists mean by "bright spot, no direct sun" — close enough to a south or east window to feel the brightness, with a sheer curtain or a few feet of distance keeping the sun off the leaves. Performs best in partial sun to full sun — 4–6 hours of direct light is ideal, reflecting its origin on open, rocky slopes. Unlike woodland heucheras, it tolerates and even prefers more sun, though afternoon shade is welcome in zones 8–9. A phone lux-meter at the leaf surface should read 1,500-3,000 lux at noon.

Watering

Water poker alumroot every 7–14 days once established; more frequent when young. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Very drought-tolerant once established, with deep roots adapted to rocky, fast-draining substrates. Water regularly during the first growing season to establish roots. Overwatering is a greater risk than underwatering — allow soil to dry between waterings.

Soil and pot

Poker alumroot grows best in gritty, sharply draining rocky or sandy loam. Native to cliff ledges and rocky outcrops; requires excellent drainage. A mix of coarse grit, perlite, and loam at roughly 1:1:2 suits container culture. pH 6.0–7.5 is acceptable. Will not tolerate heavy clay or waterlogged conditions. 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

Poker alumroot sits happiest at around 30–55% humidity and −29 °C to 38 °C (−20 °F to 100 °F). Adapted to drier western climates with low to moderate humidity. Does not require supplemental humidity. Excellent choice for dry inland gardens. Avoid high humidity paired with poor airflow, which increases fungal risk. If you keep the room above −29 °C to 38 °C 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 poker alumroot sparingly. Minimal fertilising needed — one light application of a balanced slow-release fertiliser in early spring is sufficient. Over-fertilising in a rocky, lean substrate produces rank growth that is more disease-prone. Compost top-dressing every other year is adequate. 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 poker alumroot in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Root rot from poor drainage — The biggest killer of this drought-adapted species is waterlogged soil. Ensure gritty, free-draining substrate and never allow plants to sit in water. Container plants must have drainage holes.
  • Vine weevil — Vine weevil larvae attack the fleshy roots of heucheras, causing wilting and plant death. Inspect roots when dividing and apply nematodes (Steinernema kraussei) in late summer as preventive biological control.
  • Crown exposure after frost heave — Shallow crowns heave out of the soil after freeze-thaw cycles. Press back into soil in spring and mulch with grit (not bark) to retain structure without trapping moisture.

Propagation

Divide clumps in early spring or early autumn. Seed germinates readily when surface-sown on gritty compost at 15–20 °C with light; do not cover seed. Stratification is not required. Cultivars must be propagated by division to maintain characteristics. 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

Poker alumroot is pet-safe. Heuchera cylindrica is in the same genus as other ASPCA-listed non-toxic Heuchera species. No toxic principles are reported. However, it is not individually listed by ASPCA; based on genus-level data, it is considered non-toxic to pets. 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.

Poker alumroot care — frequently asked questions

What is the common name for Heuchera cylindrica?

Heuchera cylindrica is most commonly called Poker alumroot, but it is also known as Poker alumroot, Roundleaf alumroot, Lava coral bells. The names refer to the same species, so care instructions for Poker alumroot apply identically to anything sold as Roundleaf alumroot.

How much light does poker alumroot need?

Poker alumroot grows best in bright indirect light (just back from a sunny window). Performs best in partial sun to full sun — 4–6 hours of direct light is ideal, reflecting its origin on open, rocky slopes. Unlike woodland heucheras, it tolerates and even prefers more sun, though afternoon shade is welcome in zones 8–9.

How often should I water poker alumroot?

Water poker alumroot every 7–14 days once established; more frequent when young. Very drought-tolerant once established, with deep roots adapted to rocky, fast-draining substrates. Water regularly during the first growing season to establish roots. Overwatering is a greater risk than underwatering — allow soil to dry between waterings. 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 poker alumroot toxic to cats and dogs?

Poker alumroot is pet-safe. Heuchera cylindrica is in the same genus as other ASPCA-listed non-toxic Heuchera species. No toxic principles are reported. However, it is not individually listed by ASPCA; based on genus-level data, it is considered non-toxic to pets.

What USDA hardiness zone does poker alumroot grow in?

Poker alumroot is rated for USDA zone 3–8 and RHS hardiness H7. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Poker alumroot deep-dive guides

Every aspect of poker alumroot care, each with its own calibrated guide:

Featured in these plant shortlists

Poker alumroot qualifies for 9 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Poker alumroot is also known as Poker alumroot, Roundleaf alumroot, and Lava coral bells.