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How to Grow Shisos UK | Regional Planting Calendar
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RHS propagates by seed in spring, matching the general seed-sowing convention used for other annual herbs in this catalogue.
Midlands - detail & sources
RHS propagates by seed in spring, matching the general seed-sowing convention used for other annual herbs in this catalogue.
Northern England - detail & sources
Same spring sowing window as elsewhere in the UK. A real caution kept honest: RHS rates this plant only H3, hardy in coastal and relatively mild parts of the UK (-5 to 1C) -- less reliable further north and in Scotland.
Scotland - detail & sources
Same spring sowing window as elsewhere in the UK. A real caution kept honest: RHS rates this plant only H3, hardy in coastal and relatively mild parts of the UK (-5 to 1C) -- less reliable further north and in Scotland.
Moist but well-drained (RHS); NC State: rich, moist to dry, tolerates high organic matter, good drainage, occasionally wet soil acceptable, highly resistant to heat and drought.
Lifecycle
Bushy, upright annual with toothed, aromatic, often red or purple leaves and insignificant white flower spikes in late summer (RHS). NC State: grows quickly and aggressively, self-seeds prolifically via wind dispersal, and is described as high maintenance as a result.
Propagate by seed (RHS; NC State). Grown in full sun or partial shade, in fertile, moist but well-drained soil (RHS); NC State notes it is highly resistant to heat and drought once established, spaced under 12in apart.
Growth and spread management
3
NC State: grows quickly and aggressively, self-seeding prolifically via wind dispersal, and is high maintenance as a result -- pinching off flowers before they go to seed is recommended to help slow the spread, an important step given the plant's invasive listing in several US states.
Flowering
6
RHS: insignificant, 2-lipped white flowers borne in erect spikes in late summer.
Harvest
8
RHS: used as a herb, the aromatic leaves harvested through the growing season; also used as a foliage carpet bedding plant. NC State: fast, aggressive growth means leaves are available across much of the season.
When to pick: RHS: grown as a herb as well as a foliage bedding plant; aromatic leaves are the part used. NC State: fast, aggressive growth with prolific self-seeding, so leaves are available through much of the growing season.
Storage
Used fresh -- neither source gives a specific drying or storage method for this crop.
Light: full sun to partial shade. Soil: rich, moist to dry, tolerates high organic matter and well-drained conditions; good drainage, occasionally wet soil acceptable; highly resistant to heat and drought. Hardiness USDA zones 10a-11b. Size: 1-3ft tall, 0.25-1.5ft wide, spacing under 12in. Growth: grows quickly and aggressively, high maintenance, self-seeds prolifically via wind dispersal. Propagation: seed. Pests/diseases: no serious insect or disease problems. Toxicity: can be toxic to cattle. Invasive status: listed invasive species in North Carolina, Virginia, West Virginia, Tennessee and Kentucky. Management: pinch off flowers before they go to seed to help slow the spread.
Soil: chalk, clay, loam, sand; moist but well-drained; pH acid, alkaline or neutral. Sun/aspect: full sun or partial shade, south-facing, sheltered. Size: 0.1-0.5m height/spread, 1-2 years to maturity. Hardiness H3 (-5 to 1C, coastal and relatively mild UK areas). Propagate by seed. No pruning needed. Pests: generally pest-free. Diseases: generally disease-free. Best grown in fertile, moist but well-drained soil in sun or partial shade; used as a foliage carpet bedding plant but also as a herb.
2 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.
Frequently Asked Questions
When should I sow shisos in the UK?
In Southern England, from early March. In Scotland, wait until early March. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.
When do I sow shisos?
Sow early March to mid April.
Plan next season before the problems start
Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.
UK vegetable growing guides · Checked against RHS & Met Office guidance
Every SoilCommander guide is written and maintained by our editorial team for real UK growing conditions, and reviewed against Royal Horticultural Society growing advice and Met Office climate data before publication.
Sketch your exact plot shape, pick your UK crops, and get a spacing-accurate bed layout with companion pairings, a rotation plan and month-by-month sowing dates — every fact sourced from RHS and Garden Organic.
