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SproutSmart™ Intelligent Garden Sowing

Mammoth Grey Stripe

Family: Asteraceae Oilseed and ornamental annual
Zone 6b Save Garden

Planting Schedule

Add Mammoth Grey Stripe to your garden to build a schedule and get reminders.

Mammoth Grey Stripe unfurls with a statuesque presence—heads that seem carved from dusk, their petals catching light in soft, smoky tones.

The blooms carry bold, slate-edged striping that deepens as the season advances, offering a dramatic, long-lasting show in the garden while producing abundant seed for collectors and growers. Expect sturdy, upright plants with a commanding silhouette that thrives with steady sun and rewards with striking, gallery-worthy flowers.

Light: Full SunMaturity: 90 DaysHabit: Upright

Botanical illustration of Mammoth Grey Stripe

Planting schedules and alerts are optimized for Columbus (Zone 6b).

Crop Dates

MilestoneDate
Start IndoorsDirect Sow
Last FrostApr 25th
Transplant / Sow OutdoorsApr 25th
Harvest BeginsJul 24th
Harvest EndsOct 16th

Crop Details

TraitValue
Days to Maturity90
Sun RequirementsFull SunFull sun
Growth HabitUpright
Support NeededNone
Planting DepthNormal
Germination Temp (°F)70
Min Soil Temp (°F)55
Min Night Temp (°F)40
Harden Off (days)Not Required

Frequently Asked Questions

What’s the most common disease problem for Helianthus annuus (sunflowers) and how do I manage it?
Look for downy mildew or powdery mildew as white/gray fungal growth on leaves, especially after humid weather. Improve airflow by spacing plants properly, water at the base in the morning, and remove heavily infected leaves early; for repeat outbreaks, use a labeled fungicide compatible with food/ornamentals and follow the label schedule.
How often should I water Helianthus annuus during the main growing phase?
During active growth (roughly the first 6–8 weeks after emergence), keep soil evenly moist but not soggy—aim for deep watering about 1–2 times per week depending on heat and rainfall. Check by pushing a finger 2–3 inches into the soil; water when it’s dry at that depth, since sunflowers dislike constantly wet, cool soil.
How can I tell when Helianthus annuus ‘Mammoth Grey Stripe’ is ready to harvest?
Harvest when the back of the flower head turns yellow to tan and the outer petals start to fall, while the developing seeds in the head look plump and filled out. If you rub a seed gently with your thumb, it should feel firm and come off cleanly; most crops are ready around ~90 days from sowing.

Today's Conditions

Outdoor planting for Mammoth Grey Stripe in Zone 6b typically begins around 2026-04-25. Wait until soil reaches at least 55°F before transplanting Mammoth Grey Stripe.

Garden Alerts

In Zone 6b, the average last spring frost is around April 25. Watch soil temperature before transplanting Mammoth Grey Stripe.

Today's Conditions

Outdoor planting for Mammoth Grey Stripe in Zone 6b typically begins around 2026-04-25. Wait until soil reaches at least 55°F before transplanting Mammoth Grey Stripe.

Garden Alerts

In Zone 6b, the average last spring frost is around April 25. Watch soil temperature before transplanting Mammoth Grey Stripe.

Sowing Tips

Transplant Conditions

Wait until soil reaches 55°F and nights stay above 40°F before moving outdoors.

Expert Note

Sow where you want the flowers to grow (or direct-sow early) because sunflower taproots don’t like transplanting, and tall plants need space for airflow.