Watering schedule

How often to water Shiso (Perilla frutescens var. crispa) — the schedule

Also called shiso, perilla, Japanese basil.

More about shiso

Watering at a glance

Base rhythm	Keep evenly moist; water when the top 2-3 cm of soil is dry, roughly every 3-5 days in warm weather
Spring / summer	Spring and summer: water deeply but only when the top few centimetres are properly dry — roughly weekly in the ground, more often only for pots in heat.
Autumn	Autumn: cut right back as growth slows; established plants need very little.
Winter	Winter: keep nearly dry, especially in pots — wet winter soil is the classic killer of rosemary, lavender and thyme.
Light	Direct sun (at least 4-6 hours)

About Shiso

Perilla frutescens var. crispa · also called shiso, perilla · herb

Shiso is a fast-growing annual mint relative prized in Japanese, Korean, and Vietnamese cooking for its ruffled green or deep-purple leaves and complex flavour of mint, basil, and anise. It grows easily from seed in warm weather, reaching knee-height in a season, and self-sows readily. Both leaf colours are ornamental as well as edible, thriving in sun to part shade.

Ideal humidity: 40-70%

Watch for — Wilting from underwatering: The soft foliage flags dramatically the moment soil dries out. Keep moisture consistent and mulch to buffer the root zone in hot weather.

The watering schedule, season by season

Shiso is a lean, sun-loving Mediterranean herb — it grows best kept on the dry side and rots fast if it is watered like a leafy plant. The base rhythm for shiso is keep evenly moist; water when the top 2-3 cm of soil is dry, roughly every 3-5 days in warm weather, but the real interval moves with the season, the light and the pot — so treat the figures below as a starting point and always confirm with the plant itself.

Spring & summer (active growth): Spring and summer: water deeply but only when the top few centimetres are properly dry — roughly weekly in the ground, more often only for pots in heat.
Autumn (slowing down): Autumn: cut right back as growth slows; established plants need very little.
Winter (rest / dormancy): Winter: keep nearly dry, especially in pots — wet winter soil is the classic killer of rosemary, lavender and thyme.

A soft-leaved annual that wilts quickly when dry, so it appreciates consistent moisture. Avoid letting it dry out fully, but ensure good drainage to prevent root rot in soggy soil.

Want this turned into a live reminder that adjusts to your home and the weather? The Growli watering calculator takes your pot size, light and season and returns a starting interval for shiso in seconds.

How to tell shiso needs water

A calendar is the worst way to water shiso. Check the plant and the soil instead — for this species, look for these signals in order:

The top 3-4 cm of soil is fully dry and the pot is light.
Foliage looks slightly dull or limp in heat (recovers fast once watered).
For potted plants, the rootball has shrunk slightly from the sides.

The most reliable single check is the first one on that list. When two signals agree, water; when they disagree, wait a day and look again — under-watering shiso for a day is almost always safer than over-watering it.

Overwatering vs underwatering shiso

The two failure modes can look alike at a glance, so check the soil weight and wetness before you decide. For shiso specifically:

Signs you are overwatering

Yellowing, blackening or dropping lower foliage; a sour, wet pot.
Soft, rotting stems at the base — often fatal in rosemary and lavender.
Sudden collapse despite "looking thirsty" (it was actually drowning).

Signs you are underwatering

Crisp, brittle, browning foliage and stalled growth (less common — these herbs are drought-hardy).
For young, unestablished plants only, wilting in extreme heat.

Overwatering and rich wet soil are what kill shiso, not drought. It evolved on dry, stony hillsides — err on the side of too little.

Water quality notes

Tap water is fine for shiso; drainage and restraint matter, not water type.

Seasonal and environmental adjusters

Every figure above shifts with the conditions in your home. For shiso, the levers that matter most are:

Sharp drainage is everything — grit in the mix and a terracotta pot keep it alive.
Established plants in the ground are highly drought-tolerant and rarely need watering at all.
Pots dry faster and need more attention than open ground, but still let them dry between waterings.

Pot choice is part of this too — work out the right size with the pot size calculator, since a pot that is too big stays wet long enough to rot the roots of shiso.

Shiso watering — frequently asked questions

How often should I water shiso?

Water shiso keep evenly moist; water when the top 2-3 cm of soil is dry, roughly every 3-5 days in warm weather. Spring and summer: water deeply but only when the top few centimetres are properly dry — roughly weekly in the ground, more often only for pots in heat. Winter: keep nearly dry, especially in pots — wet winter soil is the classic killer of rosemary, lavender and thyme.

How do I know when shiso needs water?

The top 3-4 cm of soil is fully dry and the pot is light. Foliage looks slightly dull or limp in heat (recovers fast once watered). For potted plants, the rootball has shrunk slightly from the sides. The single most reliable test for shiso is the first signal on that list — checking the soil or the plant directly always beats watering by the calendar.

What does an overwatered shiso look like?

Yellowing, blackening or dropping lower foliage; a sour, wet pot. Soft, rotting stems at the base — often fatal in rosemary and lavender. Sudden collapse despite "looking thirsty" (it was actually drowning). Overwatering and rich wet soil are what kill shiso, not drought. It evolved on dry, stony hillsides — err on the side of too little.

What are the signs of an underwatered shiso?

Crisp, brittle, browning foliage and stalled growth (less common — these herbs are drought-hardy). For young, unestablished plants only, wilting in extreme heat.

Can I use tap water on shiso?