How to Grow Saffron Crocuses USA

Growth Stages

Stage	BBCH	Notes
Corm planting	0	RHS: plant corms in late summer (September acceptable), 10-15cm deep, ~10cm apart, in rich but well-drained soil in a bright, sunny site; water in well. NC State: plant ~4in apart and 4in deep in well-drained soil with moderate organic matter.
Autumn flowering	6	RHS: flowers typically appear in October, often a little later in the first year -- unusual among crocuses for flowering in autumn rather than spring. NC State: purple to lavender flowers appear for a 1-2 week fall bloom period, each corm producing 2-4 flowers; the harvest window is this same short period.
Winter foliage	3	RHS: plants reach around 30cm tall over winter as grass-like leaves develop after flowering. Both sources note the flowers themselves are sterile and set no seed -- all increase is via cormlets forming underground.
Dieback and dormancy	9	RHS: foliage dies back completely in late spring, leaving the corm dormant in the soil through summer until autumn growth resumes. RHS notes a corm may take two to three years to reach flowering size after being replaced by cormlets.

Quick Facts

Factor	Value
Drainage	Rich but well-drained (RHS); NC State: loam with high organic matter and sand, good drainage, tolerates occasionally dry.
Lifecycle	Autumn-flowering perennial corm. The flowers are sterile and set no seed -- the plant increases purely by cormlets.
Edible parts	flowers

At a Glance

Harvest & Storage

When to pick: RHS/NC State: use tweezers to pick the long red stigmas from the centre of each flower, avoiding the shorter, paler orange stamens; harvest through the 1-2 week autumn bloom. Roughly 150 flowers yield 1g of dried saffron.

Storage

Dry threads on a kitchen towel on a baking rack at room temperature for at least 24 hours, then store in an airtight container away from light (RHS).

Diseases

Corm rot (saffron crocus, causal agent not yet confirmed)

low

RHS: corms may rot in storage. NC State independently names root rot in poorly drained planting sites -- a genuine corroboration that drainage is the key risk factor, both in the ground and in storage.

Saffron crocus fungal diseases (unspecified/unidentified)

low

Named only vaguely by NC State ("fungal disease risk during wet blooming periods"), no species identified -- generic entry created rather than guessing a pathogen. RHS describes the plant as generally disease-free.

Pests

Squirrels

moderate

Sciurus spp.

Named specifically by NC State as a corm-eating rodent; RHS names rodents generically.

Birds and rodents (saffron corms)

moderate

various

Generic entry for RHS's "rodents and birds" corm-predation note, corroborated independently by NC State naming squirrels and mice as corm predators.

Mice

moderate

Muridae (mice, various spp.)

Named specifically by NC State as a corm-eating rodent; RHS names rodents generically.

Sources

1. North Carolina State University Extension (Plant Toolbox) - Crocus sativus (Autumn Crocus, Saffron, Saffron Crocus)

   Light: full sun (6+ hours). Soil: loam with high organic matter and sand, good drainage, tolerates occasionally dry conditions. Size: 6-10in height, 2-4in width. Hardiness: USDA zones 5a-8b; grown in Coastal, Piedmont and Mountain regions of NC. Propagation: division, corms multiply naturally each year. Planting: ~4in apart, 4in deep, well-drained soil with moderate organic matter. Pests/diseases: fungal disease risk during wet blooming periods; root rot possible in poorly drained sites; rodents (squirrels, mice) consume corms. Harvest: orange stigmas and styles harvested during the 1-2 week fall bloom, used fresh or dried and stored in sealed containers; flowers are edible and have historical medicinal use. Growth: medium rate, low maintenance, herbaceous perennial bulb.

These source is specific to this region. The full list of 2 sources behind this guide (North Carolina State University Extension (Plant Toolbox), Royal Horticultural Society) is in the references of our UK guide to saffron crocuses; they describe the plant itself, which is the same wherever it grows.