SproutSmart
SproutSmart™ Intelligent Garden Sowing

American Flag

Leek
Zone 3a Save Garden

Planting Schedule

Add American Flag to your garden to build a schedule and get reminders.
Botanical illustration of American Flag
120d to harvest

Sweet, gently oniony flavor with a crisp, tender bite—American Flag leeks form tall, well-filled stalks that feel substantial yet stay pleasantly delicate. The pale, creamy white to light-green shafts develop with a clean, upright habit, making them ideal for roasting, grilling, and braising, as well as for fresh slicing into salads and slaws. Grow for a bold, garden-to-plate statement: mild enough for everyday use, flavorful enough to shine in sauces and pickling brines.

Crop Dates

Growing note: Zone 3a has only 109 frost-free days — shorter than this crop's 120-day maturity. Outdoor planting is not viable; use protected cultivation.
MilestoneDate
Last FrostMay 15th
Growing ApproachProtected Environment Only

Crop Details

TraitValue
Days to Maturity120
Sun RequirementsFull SunFull sun
Growth HabitUpright
Support NeededNone
Planting DepthNormal
Germination Temp (°F)55
Min Soil Temp (°F)45
Min Night Temp (°F)30
Harden Off (days)6

Today's Conditions

Outdoor planting for American Flag in Zone 3a typically begins around Indoor Lights Only. Wait until soil reaches at least 45°F before transplanting American Flag.

Garden Alerts

Zone 3a has only 109 frost-free days — shorter than this crop's 120-day maturity. Outdoor planting is not viable; use protected cultivation.

Recommended Companions

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Boro Beet
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Frequently Asked Questions

Why are my American Flag plants developing white, powdery spots on the leaves, and what should I do?
Powdery mildew is common on American Flag as the season warms, showing up as a white, powdery coating on leaves and stems. Remove and discard the worst leaves, then improve airflow by spacing plants and avoiding overhead watering. Spray with a labeled fungicide for powdery mildew (or use an organic option like sulfur or potassium bicarbonate) and reapply according to the product label at 7–10 day intervals until new growth is clean.
How can I tell when American Flag is ready to harvest at around 120 days?
Harvest when plants reach full size and the tops look mature, with uniform color and firm stems/leaves appropriate for the variety’s typical appearance. If you’re growing for foliage, start harvesting outer portions once leaves are fully expanded and healthy, then continue every few days. If you’re harvesting for a specific edible part that matures over time, begin checking earlier than 120 days and harvest when the intended part is at its firm/mature stage—avoid waiting until foliage looks tired or stays damp.
Botanical illustration of American Flag

Sweet, gently oniony flavor with a crisp, tender bite—American Flag leeks form tall, well-filled stalks that feel substantial yet stay pleasantly delicate. The pale, creamy white to light-green shafts develop with a clean, upright habit, making them ideal for roasting, grilling, and braising, as well as for fresh slicing into salads and slaws. Grow for a bold, garden-to-plate statement: mild enough for everyday use, flavorful enough to shine in sauces and pickling brines.

Today's Conditions

Outdoor planting for American Flag in Zone 3a typically begins around Indoor Lights Only. Wait until soil reaches at least 45°F before transplanting American Flag.

Garden Alerts

Zone 3a has only 109 frost-free days — shorter than this crop's 120-day maturity. Outdoor planting is not viable; use protected cultivation.

Sowing Tips

Soil Temperature

Direct sow or transplant when soil at planting depth holds 45°F for reliable germination and early growth.

Expert Note

Because it’s extremely cold-hardy, you can transplant right around last frost for a spring crop or keep it mulched to extend harvest into early spring.