Alexanders (Smyrnium olusatrum)
1 sources cited · Verified
The short answer
- Plant
- Early April to late May
- Site
- 6+ hours of sun, soil pH 5.5–7.5
In the UK, alexanders go in the ground early April to late May.
Alexanders (Smyrnium olusatrum) — biennial.
Timing is the decision that matters most in the UK: there are 4 separate regional sowing windows, ranging from early April in Southern England to early April in Scotland.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Regional Planting Calendar
Quick Facts
Soil & Growing Conditions
Growth Stages
Harvest & Storage
Alexanders, a Forgotten Pot Herb
References
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A vigorous semi-evergreen biennial reaching 75-120cm tall, with a solid stem that becomes hollow and grooved with age. Greenish-yellow flowers with a pungent, myrrh-like scent, in umbrella-like clusters. Native to the Mediterranean, also native to GB/Ireland. Hardiness H6 (-20 to -15C). Full sun, south-, west- or east-facing aspect, sheltered. Soil: sand, clay, chalk, loam; moist but well-drained or well-drained; neutral, acid or alkaline pH. Height 1-1.5m, spread 0.1-0.5m. Time to maturity 1-2 years. Propagate by seed. Generally pest-free and disease-free. Best grown in free-draining soil in full sun; grows well in coastal areas.
1 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 alexanders in the UK?
In Southern England, from early April. In Scotland, wait until early April. 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 alexanders?
Sow early April to late May.
What soil pH do alexanders need?
A pH of about 5.5–7.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
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.
Get the UK Garden Planner →Instant PDF download · Written for UK growing conditions
Last verified 2026-08-29
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.