A frequent garden question is, “Why aren’t my flowering plants blooming?” or “Why have my flowers stopped blooming?” Our garden experts at Natorp’s Nursery share insights on common flowering plants and the main causes of bloom failure.

Troubleshooting Blooming Problems in Popular Flowering Plants

Iris

If your iris plants aren’t blooming, here’s what to check:

• Overcrowding: Divide every 3–4 years in late July or August.
• Excessive Nitrogen: Avoid high-nitrogen fertilizers; bulb foods with balanced or higher P and K work best.
• Planting Depth: Ensure they’re not planted too deep.
• Sunlight Needs: Require at least a half-day of sun.
• Pests or Disease: Check for iris borers or disease.
• Transplant Recovery: Irises may take time to re-root and establish blooms.

Peony

Common reasons for peonies not blooming:

• Insufficient Sunlight: Need at least a half-day of sun.
• Recent Transplanting: Peonies may need a few years to re-establish and flower.
• Young Plants: Immature plants may not bloom.
• Nutrient Deficiency: Ensure adequate nutrients in the soil.
• Overfeeding: Avoid high-nitrogen fertilizers.
• Planting Depth: Peonies are sensitive to being planted too deep.
• Environmental Stress: Frost, disease, drought, or wet conditions can hinder blooms.

Lilac

Reasons lilacs might not bloom:

• Cold Damage: Late spring freezes or severe winters can impact flowering.
• Sunlight Needs: Require at least a half-day of sun.
• Pruning Time: Prune within 2-3 weeks of blooming; late pruning can remove buds.
• Pests/Disease: Watch for powdery mildew, borers, or scale.
• Old Wood: Promote younger growth by pruning out older wood.
• Nitrogen Overfeeding: Excess nitrogen leads to leafy growth over blooms.

Wisteria

If your wisteria isn’t flowering, consider these factors:

• Spring Freeze: Late freezes can affect bud formation.
• Seed-Grown: Plants from seed may take 8–10 years or longer to bloom.
• Excessive Nitrogen: Avoid nitrogen-rich fertilizers; use high P and K instead.
• Sunlight Needs: Needs at least a half-day of sun.
• Improper Pruning: Regular pruning encourages flowering, but heavy pruning can reduce blooms.
• Summer Drought: Lack of water during summer can hinder blooms.

Rose of Sharon

If your Rose of Sharon isn’t blooming, these may be the causes:

• Shade: Needs at least a half-day of sun.
• Moisture Issues: Buds may rot with excess moisture or overhead irrigation, or dry out in drought conditions.
• Pest Damage: Check for insect damage.
• Excess Nitrogen: Leads to foliage over blooms.

Daffodils and Spring Bulbs

Here’s why spring bulbs like daffodils may not bloom:

• Nitrogen Overfeeding: Use bulb food with lower N and higher P and K.
• Nutrient Deficiency: Ensure bulbs have adequate nutrients.
• Sunlight: Need at least a half-day of sun.
• Poor Drainage: Excess water causes bulbs to rot.
• Foliage Removal: Avoid cutting foliage too early or tying it up.
• Transplant Shock: Bulbs may skip a year of flowering if stressed.
• Crowding: Dig and divide bulbs if they become overcrowded.

Cincinnati Gardening Made Simple
Have a blooming question? Ask our garden experts!