Diagnosing Raised Bed Problems: Root Rot, Drainage, and Early Blight

Symptoms and Causes

Lush foliage followed by black-spotted leaves, blossom drop, and mushy stems suggests multiple issues: overwatering leading to root rot, poor drainage, and possibly early blight (Alternaria solani). Low nitrogen initially, then improvement after blood meal, indicates nutrient imbalance.

Investigating Drainage

Dig a test hole to the bed bottom. If soil is slurry-like, not moist like a wrung sponge, drainage is inadequate. Solutions:

• Add coarse aggregate (gravel, perlite) to the bed base.
• Install perforated PVC drain pipes if underlying soil is clay.
• Ensure beds are at least 12 inches deep.

Managing Early Blight

• Remove all diseased plant debris immediately—fungus overwinters on foliage.
• Rotate crops: avoid planting tomatoes in the same spot for 3 years.
• Space plants generously for air circulation.
• Water at soil level, never overhead.
• Apply sulfur dust or copper fungicide preventatively.

Soil Building for Long-Term Health

Amend beds annually with compost, aged manure, and peat moss. This improves structure, drainage, and nutrient retention, reducing both waterlogging and disease pressure.