How to Grow Skirret

Soil & Growing Conditions

Water: moist but well-drained; water during dry spells if roots are to be harvested (RHS)

Growth Stages

Stage	BBCH	Notes
Sowing/planting	0	Grow from seed sown after all danger of frost, or from a purchased crown/root offset for a head start; can also start indoors 8 weeks before the last frost (PITH + VIGOR).
Root and foliage growth	3	Grows 3-4ft tall with large, glossy, dark green, compound pinnate leaves; harvest follows 6-8 months after planting (PITH + VIGOR).
Flowering	6	Delicate white flower umbels appear in summer, also giving the plant ornamental value (RHS).
Dormant-season harvest and division	8	Lift and divide clumps when dormant, November to March, harvesting some roots and replanting sections for continued growth (RHS).

Quick Facts

Factor	Value
Soil texture	chalk, clay, loam or sand, deep and fertile (RHS)
Drainage	well-drained
Lifecycle	herbaceous perennial
Edible parts	root

At a Glance

Harvest & Storage

When to pick: Lift and divide clumps when dormant, between November and March; white roots taste like sweet carrots and parsnips, harvested for culinary use while some sections are replanted for continued growth (RHS).

Pests

Stem and bulb nematode

moderate

Ditylenchus dipsaci

RHS names this directly: susceptible to stem and bulb eelworm.

Voles

low

Microtus spp. / Arvicola spp.

RHS names this directly: voles may eat the roots.

Skirret, the Sweet-Rooted Perennial the Tudors Grew

Umbellifer flowers

The white compound umbels place skirret firmly in the carrot family, alongside parsnip and carrot.

Sources

1. Cultivariable - Skirret (Sium sisarum) -- how to grow

   Specialist grower guide for unusual root crops. Direct sow mid-autumn to late spring, or start indoors 8 weeks before last frost for full-size first-year roots; seed germinates slowly and erratically, first germinations around 3 weeks and 50% emergence by week 6, helped by consistent moisture and bottom heat. Propagates easily from offsets ringing the stem -- select offsets with large shoots and rootlets, pot them with the sprout tip just below the surface, which improves survival over direct planting. Space 18in apart in rows 3ft apart, sowing seed about 1/8in deep. Acidic to neutral, well-drained soil rich in organic matter; responds to nitrogen and tolerates heavy, swampy ground. Full sun optimal, tolerates shade with reduced yields. Harvestable after the first year once foliage dies back, with yields improving markedly in year two. DISAGREES WITH RHS ON TWO POINTS: says frost does NOT appear to improve the roots (commonly claimed elsewhere), and names black blight (Septoria) as a major disease threat plus root knot nematodes, where RHS reports the plant as generally disease-free. Pests: voles eat the roots; tiny seed-feeding beetles damage flower heads.

2. PITH + VIGOR - Skirret (Sium sisarum) - An Exciting Option for a Perennial Vegetable Garden

   A secondary gardening reference rather than a university or horticultural authority, used for propagation-method and timing detail RHS's basic profile does not cover, not contradicted by it. Can be grown from seed or from a purchased crown/root offset for a head start. A hardy, cool-season crop, directly sown after all danger of frost, or started indoors for transplant eight weeks before the last frost, with harvest six to eight months later. Grows 3-4ft tall with large, glossy, dark green, compound pinnate leaves and greyish-white roots clustering from the base.

3. Plants For A Future (PFAF) - Sium sisarum

   PFAF entry for Sium sisarum. Fetched and parsed directly for the USDA hardiness rating.

These 3 sources are specific to this region. The full list of 4 sources behind this guide (Cultivariable, PITH + VIGOR, Plants For A Future (PFAF) and others) is in the references of our UK guide to skirret; they describe the plant itself, which is the same wherever it grows.