Lupine Care: Growing Showy Spires
Lupines (Lupinus) command attention in the late spring and early summer garden with their tall, stately spires densely packed with pea-like flowers. Available in a rainbow of colors, including blues, purples, pinks, reds, yellows, whites, and bicolors, they create dramatic vertical accents. While stunning, garden lupines, especially the popular Russell Hybrids, can sometimes be finicky, demanding specific conditions like cool temperatures, full sun, and perfectly drained soil.
Common Types of Lupines
- Russell Hybrids: Most common garden type. Complex hybrids; dense spikes in many colors. Often short-lived perennials (3-5 years), especially in heat/heavy soil. Prefer cooler summers. Zones 4-7(8).
- Wild Lupines (Species): Vary greatly. Examples: L. perennis (Wild Lupine - native East NA, blue/purple, needs sandy acid soil, Zones 3-8), L. texensis (Texas Bluebonnet - annual), L. arboreus (Tree Lupine - shrubby yellow, coastal Zones 7-10).
- Other Series: Newer series aim for better heat tolerance or compact habits (e.g., 'Gallery' series).
Planting Lupines
Lupines have specific requirements and dislike root disturbance.
Starting from Seed (Recommended)
- Timing: Sow indoors 6-8 weeks before last frost, or direct sow outdoors in early spring or fall.
- Preparation: Scarify (nick seed coat) and/or soak seeds overnight to improve germination.
- Sowing: Sow 1/4 inch deep. Use peat pots if starting indoors. Keep moist. Germination 2-4 weeks. Consider rhizobial inoculant.
Planting Container-Grown Plants
- Timing: Plant in spring after last frost.
- Handling: Be extremely careful not to disturb the root ball! Handle gently.
Ideal Growing Conditions
- Light: Full sun (6+ hours) preferred. Tolerates very light shade, especially afternoon shade in hot areas.
- Soil: CRITICAL: Requires excellently drained, slightly acidic to neutral soil. Sandy loam or gravelly soil ideal. Will fail in heavy, wet clay. Good drainage more important than high fertility.
- Temperature: Prefer cool summers. Struggle in heat/humidity.
- Spacing: Space 1-1.5 feet apart.
Planting Technique
Cool sun and sharp drainage key. Avoid rich, heavy soils.
Loosen soil deeply. Amend heavy soil for drainage (grit/sand helpful) but avoid excessive organic matter or fertilizer.
Dig hole just large enough for root ball or prepare seedbed.
(Plants): Slide carefully from pot, disturbing roots minimally. Plant at same depth. (Seeds): Sow prepared seeds.
Fill hole/cover seeds, firm gently. Water thoroughly. Keep consistently moist until established/germinated.
Lupines' deep taproots make them very difficult to transplant successfully once established. Choose your planting location carefully.
Watering Lupines
- Keep soil consistently moist after planting/sowing until established.
- Once established, water regularly during dry periods, especially during bloom, keeping soil moderately moist. Good drainage is essential.
Fertilizing Lupines
- Generally not needed or recommended. Lupines fix nitrogen. Fertilizing encourages foliage over flowers. Thrive in average to lean soil.
Maintenance and Care
Deadheading
- Removing spent flower spikes promptly may encourage a smaller secondary bloom and can slightly prolong plant life. Cut spike back to leaves. Preventing seed formation is optional; self-sowing maintains presence (hybrids may vary).
Staking
- Tall varieties may require staking in windy sites or rich soil. Install stakes early.
Lifespan
- Many garden lupines are short-lived perennials (3-5 years). Plan to replant or allow self-sowing.
Troubleshooting Common Problems
Lupines can be susceptible to several issues if conditions aren't ideal.
Powdery Mildew
Symptoms and Management
White powdery coating on leaves, especially in humidity/poor circulation.
- Prevention/Control: Full sun, good air circulation. Avoid overhead watering. Choose resistant varieties if possible.
Aphids (Especially Lupine Aphid)
Symptoms and Management
Large colonies infest stalks/leaves, weakening plant.
- Control: Monitor regularly. Wash off with strong water spray. Use insecticidal soap for heavy infestations. Encourage ladybugs.
Root Rot
Symptoms and Management
Plants wilt, yellow, collapse. Roots brown/mushy.
- Cause: Poor drainage, overly wet soil.
- Prevention: Provide excellent drainage! Amend heavy soil or use raised beds. Avoid overwatering.
- Treatment: Usually fatal. Improve drainage before replanting.
Failure to Thrive or Bloom
Possible Causes and Solutions
- Poor Drainage: Most common cause.
- Too Much Heat/Humidity: Prefer cool summers.
- Transplant Shock: Resent root disturbance.
- Soil Too Rich/Fertile: Causes weak growth.
- Insufficient Sun: Needs full sun.
Conclusion
Lupines offer breathtaking spires of color in the early summer garden. While somewhat demanding regarding drainage and cool temperatures, and often short-lived, their beauty makes them worthwhile. Starting from seed, providing excellent drainage and full sun, and avoiding transplant shock are keys to success. Remember their toxicity.
