Pioneer 399

Corn

Zone 13b Save Garden

🌱 72d to harvest Upright

Sunlit kernels burst with a buttery sweetness—Pioneer 399 delivers tender, juicy yellow ears that feel silk-smooth at first bite …

Crop Dates

Milestone	Date
Start Indoors	Direct Sow
Last Frost	Jan 1st
Transplant / Sow Outdoors	Jan 1st
Harvest Begins	Mar 14th
Harvest Ends	—

Crop Details

Trait	Value
Days to Maturity	72
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	60
Min Soil Temp (°F)	55
Min Night Temp (°F)	45
Harden Off (days)	Not Required

Recommended Companions

Long Feng Cucumber

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Chianti Sunflower

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Excelsior Cucumber

Frequently Asked Questions

What pest or disease is most likely on sweet corn (Zea mays var. saccharata), and what should I do?

Watch for corn earworm (Helicoverpa zea), which bores into the ear right after silks emerge and often leaves frass near the silk ends. Apply Bacillus thuringiensis (Bt) as directed when silks first appear and again as needed per label, and remove heavily damaged ears early to reduce spread. Also keep the area free of old corn debris between plantings to lower overwintering pest and disease pressure.

How often should I water sweet corn during the main growing phase?

During tassel and ear development, water so the soil stays evenly moist at the root depth (about 6–8 in / 15–20 cm), typically around 1–1.5 in (2.5–4 cm) of water per week depending on weather. Water deeply 1–2 times per week rather than frequent light sprinkling, and avoid letting the soil dry out completely because that can cause poor ear fill and stressed plants. If leaves start to wilt in midday and the soil is dry several inches down, water immediately.

How can I tell when this sweet corn is ready to harvest?

Harvest when the silks have turned dark and the kernels feel full and milky when punctured—usually about 18–24 days after the first silks appear on the ears. If you see kernels that are still watery or tightly closed, wait a few more days and check again. For peak sweetness, pick in the morning and refrigerate promptly.

Sunlit kernels burst with a buttery sweetness—Pioneer 399 delivers tender, juicy yellow ears that feel silk-smooth at first bite and hold their flavor through the season. Expect plump, well-filled cobs with a bright, even color and a crisp-tender texture that’s ideal for fresh enjoyment and quick roasting, as well as creamy summer sauces and relishes. Grow this 72-day yellow sweet corn for a reliable harvest of garden-fresh ears that taste like pure sunshine.

Sowing Tips

Transplant Conditions

Wait until soil reaches 55°F and nights stay above 45°F before moving outdoors.

Expert Note

For best sweet flavor, grow in blocks (not rows) and keep soil evenly moist after tasseling; harvest when kernels are filled and milky (about 18–22 days after silk).