Growing 600 Tree Seedlings Indoors to 10 Feet: Reality Check

600 Colorado blue spruce & white pine seedlings (1.5 yr, 1.5 ft tall) in 12" pots. Want to move indoors under fluorescents, grow to 10 ft in 5 years, then plant out. Toronto.

Math Problem

• 10-ft tree = ~60 sq ft canopy.
• 600 trees = 36,000 sq ft = a warehouse.
• Lighting: 40–50 watts/sq ft for conifers = 1.5+ MW. Your meter spins; authorities notice.

Biology Problem

• These species are hardy to Zone 3. At 8–10" tall, they need outdoor winter (cold stratification, dormancy).
• Indoor "eternal summer" weakens them. They'll stretch, get pests, fail at planting.

Real Path

1. Grow under lights / sunny window for Year 1–2 only.
2. Move outside permanently. Cold frame or mulched beds for winter.
3. Pot up annually. Field-plant at 3–4 ft (Year 4–5).

Greenhouse > grow room. Sun does the work for free.

Your church's 15-ft Norfolk pine? It's tropical. Different rules.