Fertilizer for Impatiens: NPK Guide and Application Rates
Impatiens are moderate feeders that produce continuous blooms in shaded locations with regular fertilization. Purdue University Extension recommends incorporating slow-release fertilizer at planting or feeding every 2-3 weeks with water-soluble fertilizer. New Guinea impatiens tolerate more sun and are slightly heavier feeders than standard shade impatiens. Both types are self-cleaning and rarely need deadheading.
Quick Reference
What NPK Ratio is Best for Impatiens?
The recommended NPK ratio for impatiens is 10-10-10. A balanced 10-10-10 feeds all three macronutrients equally, which works well when soil tests show no single deficiency.
Impatiens NPK needs shift at each growth stage. Balanced formula for transplants once established during the Seedling phase, then moderate phosphorus boost for continuous color once flowering begins.
NPK by Growth Stage for Impatiens
| Growth Stage | NPK Ratio | Notes |
|---|---|---|
| Seedling | 10N 10P 10K N 10% Nitrogen: leaf and stem growth P 10% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Balanced formula for transplants once established |
| Vegetative | 10N 10P 10K N 10% Nitrogen: leaf and stem growth P 10% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Balanced nutrition supports rapid mounding growth |
| Flowering | 10N 15P 10K N 10% Nitrogen: leaf and stem growth P 15% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Moderate phosphorus boost for continuous color |
| Fruiting | 10N 10P 10K N 10% Nitrogen: leaf and stem growth P 10% Phosphorus: roots and flowers K 10% Potassium: health and disease resistance Learn more about NPK | Balanced feeding through first frost |
When Should You Fertilize Impatiens?
In zone 3, start fertilizing impatiens in June. In zone 10, begin as early as February. Apply every 3 weeks through the growing season.
Which Zones Can Grow Impatiens?
Impatiens grows in USDA zones 3 through 10, spanning a 8-zone range.
Fertilization Start by Zone
| Zone | Start Month |
|---|---|
| Zone 3 | June |
| Zone 4 | June |
| Zone 5 | May |
| Zone 6 | May |
| Zone 7 | April |
| Zone 8 | March |
| Zone 9 | March |
| Zone 10 | February |
What Are the Best Fertilizer Products for Impatiens?
Look for products with an NPK close to 10-10-10. Osmocote Smart-Release is the most popular choice among home gardeners for impatiens.
- Osmocote Smart-Release
- Miracle-Gro All Purpose
- Jack's Classic
Prices vary by retailer and region. Check current pricing before purchasing.
Container and Raised Bed Adjustments for Impatiens
Excellent shade container plant; feed every 2 weeks with liquid fertilizer or use slow-release at planting
Common Fertilizing Mistakes with Impatiens
- Planting standard impatiens in full sun, where they wilt and need much more water and fertilizer.
- Over-fertilizing, which produces lush foliage but stretched, leggy plants with fewer blooms.
- Confusing nutrient deficiency with downy mildew symptoms; check for white spore masses on leaf undersides.
- Applying granular fertilizer when foliage is wet, causing leaf burn.
Tips for Fertilizing Impatiens
- Incorporate slow-release fertilizer at planting for season-long nutrition with minimal effort.
- New Guinea impatiens in more sun need more frequent feeding than standard shade impatiens.
- Avoid wetting foliage when applying liquid fertilizer to reduce downy mildew risk.
- Impatiens are self-cleaning and redirect energy to new blooms without deadheading.
Organic Fertilizer Alternatives for Impatiens
Sources
Source:Purdue University ExtensionLast updated: