Full-spectrum LED lights are the current standard for indoor cannabis growing. They produce less heat than HPS, use less electricity, and can be tuned for different growth stages.

• LED — Most efficient; 40-50W actual draw per square foot for flowering
• HPS — Proven results; 600W covers a 4x4 foot area effectively
• CMH (Ceramic Metal Halide) — Excellent spectrum; 315W covers 3x3 feet

A 4x4 foot (1.2x1.2m) tent typically holds 4-9 plants depending on strain size and training methods. Fewer larger plants or more smaller plants can produce similar total yields with proper techniques.

• 4 plants — SCROG or mainlining; more veg time, larger plants
• 9 plants — SOG method; shorter veg time, faster harvest cycles

Optimal conditions vary by growth stage. Vegetative plants prefer 70-80°F (21-27°C) with 50-70% humidity. During flowering, lower temperatures to 65-75°F and reduce humidity to 40-50% to prevent mold and promote resin production.

Northern Lights, OG Kush, and Granddaddy Purple are top choices for indoor growing. These indica-dominant strains stay compact, have short flowering times (7-9 weeks), and produce dense, resinous buds.

A standard 4x4 tent with a full-spectrum LED light uses 400-600 kWh per month, adding roughly $40-80 to your electricity bill depending on your local rate. Electricity is the second-largest ongoing cost after seeds and nutrients.

• Lighting (70% of total) — A 400W LED running 18 hours/day uses ~216 kWh/month in veg, ~144 kWh/month at 12/12 in flower
• Ventilation (15%) — Inline fan + oscillating fan running 24/7 adds ~40-60 kWh/month
• Pumps & timers (15%) — Minimal draw; ~10-20 kWh/month for automated watering and controllers
• LED vs. HPS — LEDs use 30-40% less electricity than equivalent HPS setups while producing less heat (reducing cooling costs)

Want to skip electricity costs entirely? Grow outdoor seeds using free sunlight. Looking for a shorter cycle to reduce total power use? Autoflower seeds finish 4-6 weeks faster than photoperiod strains.