Nepeta 'Six Hills Giant' (Six Hills Giant catmint) care

Light

Most houseplants will scorch where nepeta 'six hills giant' thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Full sun is essential for compact growth and maximum flowering. In shade it grows lax, flowers poorly and is more prone to flopping open at the centre. A plant moved abruptly from low light to direct sun bleaches in 48 hours — always acclimatise over a week.

Watering

Aim for when soil is dry to a few centimetres; infrequently once established for nepeta 'six hills giant', 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. Strongly drought-tolerant. Water new plants through their first season, then only in extended dry spells. It strongly dislikes wet, heavy soil, which rots the crown.

Soil and pot

Nepeta 'Six Hills Giant' grows best in free-draining, light soil of low to moderate fertility. Thrives in poor, dry, gritty or sandy soils and tolerates chalk. Sharp drainage is key, especially over winter. Avoid rich, moist ground, which causes lush, floppy growth. 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

Nepeta 'Six Hills Giant' sits happiest at around Ambient outdoor humidity humidity and -29 to 30°C (-20 to 86°F). A Mediterranean-style sun-lover that prefers dry air and good airflow; high humidity with poor ventilation can encourage mildew. 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 nepeta 'six hills giant' sparingly. Needs very little. Skip feeding in average soil; a thin spring mulch is enough on poor ground. Feeding rich soils produces weak, flopping stems and fewer flowers. 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 nepeta 'six hills giant' in the Growli community. Each is annotated with the most common cause so you know where to start.

• Mid-season collapse — The clump can splay open and look tired after the first flush. Shear hard by a third to a half to trigger fresh growth and a second bloom.
• Cats rolling on plants — The aromatic foliage attracts cats that flatten and crush young plants. Protect with low twiggy supports until established.
• Crown rot in wet soil — Heavy, wet ground rots the crown, especially in winter. Plant in sharply drained soil and add grit to clay.
• Powdery mildew — Can appear in humid, crowded conditions or after drought stress. Improve airflow and cut back affected growth.

Propagation

Sterile and seedless, so propagate vegetatively: divide in spring or autumn, or take basal softwood cuttings in late spring, which root quickly. 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

Nepeta 'Six Hills Giant' is mildly toxic to pets. The ASPCA lists Catnip (Nepeta cataria), the type species of this genus, as toxic to cats, with nepetalactone as the toxic principle causing vomiting, diarrhoea and either sedation or stimulation. As a Nepeta, 'Six Hills Giant' should be treated the same; verify any individual concern with a vet. Most cats are attracted to and only mildly affected by catmint. 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.

Nepeta 'Six Hills Giant' deep-dive guides

Every aspect of nepeta 'six hills giant' care, each with its own calibrated guide:

• Nepeta 'Six Hills Giant' watering schedule
• Nepeta 'Six Hills Giant' light requirements
• Best soil mix for nepeta 'six hills giant'
• Nepeta 'Six Hills Giant' fertilizing guide
• When to repot nepeta 'six hills giant'
• How to propagate nepeta 'six hills giant'
• Nepeta 'Six Hills Giant' growth rate & size
• Nepeta 'Six Hills Giant' cold hardiness
• Nepeta 'Six Hills Giant' temperature & humidity
• Is nepeta 'six hills giant' toxic to cats & dogs?
• Is nepeta 'six hills giant' toxic to cats?
• Is nepeta 'six hills giant' toxic to dogs?
• Getting nepeta 'six hills giant' to bloom

Featured in these plant shortlists

Nepeta 'Six Hills Giant' qualifies for 6 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best drought-tolerant houseplants — Houseplants that prefer to dry out — forgiving of forgotten watering and ideal for travel or busy weeks.
• Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
• 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 fragrant houseplants — Indoor plants with scented flowers or aromatic foliage — greenery you can smell, selected from our care library.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Nepeta 'Six Hills Giant' is also commonly called Six Hills Giant catmint or tall catmint.

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