Flat Dutch Giant

Cabbage

100d to harvest

Sink your senses into Flat Dutch Giant’s crisp, cool crunch—an invitingly mild, cabbage-sweet flavor with a satisfyingly firm bite. At maturity, heads form broad and notably flattened, wrapped in attractive blue-green leaves that hold their shape beautifully in the garden. Ideal for hearty salads, slaws, and braises, this is a dependable choice for gardeners who want a substantial, showy head that performs through the season.

Crop Dates

Growing note: In frost-free Zone 11a, grow this cool-season crop during the cooler dry season (October–February).

Milestone	Date
Start Indoors	—
Climate	Frost-Free Climate
Transplant / Sow Outdoors	Oct 1st
Harvest Begins	Jan 9th
Harvest Ends	Feb 28th

Crop Details

Trait	Value
Days to Maturity	100
Sun Requirements	Full Sun
Growth Habit	Rosette
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	45
Min Soil Temp (°F)	40
Min Night Temp (°F)	30
Harden Off (days)	6

Frequently Asked Questions

What pest or disease is most common on Brassica oleracea var. capitata (Flat Dutch Giant cabbage), and how do I treat it?

Watch for cabbage worms (imported cabbageworm/diamondback moth) and clubroot. For worms, spray Bt (Bacillus thuringiensis) when you first see small holes or tiny green larvae, and reapply after 5–7 days if needed. To reduce clubroot, avoid planting in the same bed for several years, keep soil moisture consistent (not waterlogged), and apply lime according to a soil test to maintain a near-neutral pH.

How often should I water Flat Dutch Giant cabbage during the main head-forming phase?

During head formation (roughly mid-season onward), keep soil evenly moist about 1–1.5 inches per week total, split as needed to prevent drying out completely between waterings. Water deeply so moisture reaches the root zone, then let the top couple inches dry slightly to avoid stagnant, soggy soil that encourages disease. Irregular moisture can lead to stunted heads and increased risk of cracking.

How can I tell when Flat Dutch Giant cabbage is ready to harvest?

Harvest when heads feel firm and solid in the center and reach a good size for “giant” types, typically around 100 days from sowing (your exact date depends on transplant time). If you squeeze the head gently, it should resist compression, not feel soft or springy. Leave it a bit longer only if weather stays mild—hard frosts can damage outer leaves even if the core is close to ready.