Shiso (Perilla) (Shiso) care

Light

Aim for at least 4-6 hours of direct sun on the leaves. Full sun (6+ hours) gives the strongest leaf colour and flavour, though it tolerates partial shade with 2-6 hours of direct light. Indoors, place at a bright south- or west-facing window or under a grow light. Seeds need light to germinate, so sow on the soil surface and do not bury them. If your only bright window faces south, that's perfect for shiso (perilla) — same window any aroid would fry on.

Watering

Watering shiso (perilla): roughly every 2-4 days; whenever the top 2-3 cm of soil feels dry. 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 the soil consistently just-moist for tender, fast leaf growth. Established plants are heat- and drought-resistant and will survive drier soil, but flavour and yield drop. Avoid waterlogging, which invites root rot and powdery mildew. Containers dry quickly in summer and may need daily watering.

Soil and pot

Shiso (Perilla) grows best in rich, fertile, well-draining loam with high organic matter. Thrives in medium to rich, moisture-retentive soil amended with compost; tolerates sandy soils and a wide pH range around neutral (about 6.0-7.0). Good drainage is essential. For pots, use a quality all-purpose potting mix in a container at least 15 cm (6 in) deep and wide. 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

Shiso (Perilla) sits happiest at around 40-60% (average to slightly high) humidity and 18-30 C (65-86 F). Shiso enjoys warm, humid summer conditions and average household humidity is fine. In very dry indoor air, raise it occasionally with a pebble tray, but prioritise airflow, since stagnant humid conditions encourage powdery mildew and fungal leaf spot. If you keep the room above 18 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 shiso (perilla) sparingly. Feed every 3-4 weeks during active growth with a balanced or slightly nitrogen-forward liquid fertiliser (such as a 10-10-10 or fish emulsion) at half to full strength to fuel leafy growth. Rich soil amended with compost at planting reduces the need. Avoid over-feeding, which produces lush but blander leaves. 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 shiso (perilla) in the Growli community. Each is annotated with the most common cause so you know where to start.

• Premature bolting and flowering — Long summer days (over ~14.5 hours of daylight) trigger flowering, after which leaf production stops and the foliage turns bitter and tough. Pinch tips often and remove flower spikes as soon as they appear to prolong the harvest.
• Powdery mildew and fungal leaf spot — Humid, crowded or poorly drained conditions cause white powdery coating or dark spots on leaves. Improve airflow, space plants 20-30 cm apart, water at the soil line, and avoid overhead watering.
• Aggressive self-seeding / invasiveness — Shiso reseeds prolifically and is considered invasive in parts of the eastern US. Deadhead flowers before seeds set, or grow in containers, to stop it taking over the garden.
• Frost and cold damage — It is not frost-hardy and collapses at the first frost. Do not plant out until after the last frost and night temperatures stay above about 10 C (50 F); bring containers indoors before cold snaps.
• Leggy, sparse growth — Too little light or skipped pinching produces tall, floppy stems with few leaves. Give full sun (or a grow light indoors) and pinch growing tips regularly to keep plants compact and bushy.
• Flea beetles and slugs — Small shot-holes in young leaves point to flea beetles, while slugs and snails chew ragged edges. Use row cover on seedlings, hand-pick at dusk, and keep the area free of debris.

Propagation

Easiest from seed: surface-sow on warm, moist soil and press in lightly without covering, since seeds need light to germinate at around 20 C (68 F); germination can be slow, so cold-stratifying seed or sowing fresh improves rates. Thin or transplant seedlings 20-30 cm apart after frost. Stem cuttings also root readily in water or moist soil, and plants self-seed freely. 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

Shiso (Perilla) is mildly toxic to pets. Perilla frutescens is NOT individually listed in the ASPCA toxic or non-toxic plant database, and no other Perilla species is ASPCA-listed, so there is no "clean genus" basis to call it pet-safe. The plant contains perilla ketone (concentrated in stems, flowers and seeds), a well-documented lung toxin that causes severe respiratory distress in grazing livestock; pet poison references report respiratory and gastrointestinal signs in dogs and cats. Treat it as mildly toxic, keep it away from pets and livestock, and consult your vet if ingestion is suspected. 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.

Shiso (Perilla) deep-dive guides

Every aspect of shiso (perilla) care, each with its own calibrated guide:

• Shiso (Perilla) watering schedule
• Shiso (Perilla) light requirements
• Best soil mix for shiso (perilla)
• Shiso (Perilla) fertilizing guide
• When to repot shiso (perilla)
• How to propagate shiso (perilla)
• Shiso (Perilla) growth rate & size
• Shiso (Perilla) cold hardiness
• Shiso (Perilla) temperature & humidity
• Is shiso (perilla) toxic to cats & dogs?

Related guides

Shiso (Perilla) is also known as Shiso, Perilla, Beefsteak plant, Perilla mint, Japanese basil, and Purple mint.

• Basil care — light, water and common problems
• Herb garden care — light, water and common problems
• Mint care — light, water and common problems
• All 609 plant care guides in the Growli library