When to Plant Impatiens in Bullhead, South Dakota (57621)

Location

Bullhead, South Dakota

ZIP Code

57621

USDA Zone

Last Frost

Tuesday, May 5, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Tuesday, February 24, 2026

Transplant Outdoors

Tuesday, May 19, 2026

Based on last frost Tuesday, May 5, 2026 · Zone 4b

Pro tip: Start Impatiens seeds indoors 10 weeks before your last frost date, then transplant outdoors around Tuesday, May 19, 2026.

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🌿 Plant Details

Scientific Name Impatiens walleriana

Days to Maturity 60 days

Mature Height 8-18"

Spread 12"

☀️ Growing Requirements

☀️

Sun

Partial to Full Shade (2-4 hours)

💧

Water

Regular (1-2 inches/week)

↔️

Spacing

8" apart

🌱

Planting Depth

0.125" deep

Seeds typically germinate in 14-21 days

Ready to Plant Impatiens in Bullhead?

Get your seeds now so they're ready by Tuesday, February 24, 2026.

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🤝 Good Companions

BegoniaFernHostas

🤝

Full Companion Planting Guide for Impatiens

See which plants help Impatiens thrive, which to keep away, and raised bed layout tips →

🛠️ Supplies You'll Need

🌱 Seed Starting Trays 🪴 Seed Starting Mix 💡 Grow Lights 🌡️ Heat Mat 🌍 Flower Garden Soil ✂️ Pruning Shears 🚿 Watering Can

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🌾 Seed Saving Guide

🟡 Moderate

⚠️ Many varieties are F1 hybrid — look for OP/heirloom types

When to Harvest Seed

Seed pods explode when touched — bag ripening pods with a rubber band before they burst.

Processing

Collect seeds from bags as pods burst. Tiny seeds — dry on paper towel for 1 week.

Seed Viability

Up to 2 years when stored cool, dark, and dry.

Pro Tip

Most garden impatiens are F1 hybrids. New Guinea impatiens are almost always hybrid — look for old-fashioned OP varieties.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 72 plants of Impatiens. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Impatiens in Bullhead, South Dakota? +

In Bullhead (Zone 4b), start Impatiens seeds indoors around Tuesday, February 24, 2026 and transplant outdoors around Tuesday, May 19, 2026.

What is the last frost date for Bullhead, South Dakota? +

The average last spring frost date for Bullhead, South Dakota (ZIP 57621) is around Tuesday, May 5, 2026. This is based on NOAA climate normals for USDA Zone 4b.

How long does Impatiens take to grow? +

Impatiens typically matures in about 60 days from transplanting. In Bullhead, that means you can expect harvest around Tuesday, May 19, 2026 plus 60 days.

Should I start Impatiens indoors or direct sow in South Dakota? +

Impatiens should be started indoors 10 weeks before your last frost date. In Bullhead, that means starting around Tuesday, February 24, 2026.

📚 More Impatiens Planting Guides

🗺️

Impatiens in South Dakota

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 4b Impatiens Guide

All cities in your zone · Avg dates

→

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Growing Impatiens in Zone 4b

Impatiens (Impatiens walleriana) is a popular garden vegetable. In Bullhead, South Dakota, which is in USDA Hardiness Zone 4b, you should start seeds indoors around Tuesday, February 24, 2026.

Your average last frost date is Tuesday, May 5, 2026. Plan to transplant your Impatiens seedlings outdoors around Tuesday, May 19, 2026, about 2 weeks after your last frost date.