SproutSmart
SproutSmart™ Intelligent Garden Sowing

Red Boy

Family: Asteraceae Flower
Zone 6b Save Garden

Planting Schedule

Add Red Boy to your garden to build a schedule and get reminders.

Velvety petals in a vivid “Red Boy” blaze—an arresting crimson that seems to glow against cool, silvery-green foliage.

This bachelor’s button forms tidy, upright blooms with a crisp, satiny texture and a classic, button-like center that holds its shape beautifully through the season. Grow for long-lasting garden color in beds and borders, and let the fresh, airy flower heads lend charm to arrangements and dried displays.

Light: Full SunMaturity: 70 DaysHabit: Upright

Botanical illustration of Red Boy

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

Crop Dates

MilestoneDate
Start IndoorsMar 21st
Last FrostApr 25th
Transplant / Sow OutdoorsApr 25th
Harvest BeginsJul 4th
Harvest EndsOct 16th

Crop Details

TraitValue
Days to Maturity70
Sun RequirementsFull SunFull sun
Growth HabitUpright
Support NeededNone
Planting DepthNormal
Germination Temp (°F)65
Min Soil Temp (°F)40
Min Night Temp (°F)35
Harden Off (days)5

Frequently Asked Questions

What pest or disease commonly affects Centaurea cyanus (red cornflower), and how do I control it?
Cornflower (Centaurea cyanus) is prone to powdery mildew and sometimes aphids, especially in crowded, humid growth. Improve airflow by spacing plants and removing badly affected leaves early, then spray with an appropriate fungicidal/anti-mildew product labeled for powdery mildew on flowering ornamentals. For aphids, dislodge with a strong water spray and repeat as needed, or spot-treat with an insecticidal soap when aphid clusters appear.
How often should I water Centaurea cyanus during its main growing phase?
During the main growth period (after seedlings establish and while plants are actively leafing and budding), water so the top 1 inch of soil dries slightly between waterings—typically about 1 inch per week total from rainfall plus irrigation. In full sun, expect more frequent watering in hot spells, but avoid keeping the soil constantly wet because it increases mildew risk.
How can I tell when to harvest Centaurea cyanus (red cornflower)?
Harvest when the flower heads are fully formed and show strong color, but before petals fade or the center starts to look deflated. For best vase life, cut in the morning when stems are cool, and make your cuts just above a leaf node to encourage branching. Plants usually reach harvestable bloom around 70 days from sowing under good conditions.

Today's Conditions

Outdoor planting for Red Boy in Zone 6b typically begins around 2026-04-25. Wait until soil reaches at least 40°F before transplanting Red Boy.

Garden Alerts

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

Today's Conditions

Outdoor planting for Red Boy in Zone 6b typically begins around 2026-04-25. Wait until soil reaches at least 40°F before transplanting Red Boy.

Garden Alerts

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

Sowing Tips

Transplant Conditions

Wait until soil reaches 40°F and nights stay above 35°F before moving outdoors. Harden off for 5 days first.

Expert Note

Sow thinly and keep seedlings cool for compact plants; pinching is optional but can improve branching for fuller flower heads.