Lighting for a 240cm x 120cm area - 2.88m²: the complete guide

Effectively lighting a grow space of 240cm x 120cm, or 2.88m², requires a thoughtful approach. This rectangular area offers an excellent balance between productivity and space management, but requires adapted lighting to avoid shadows and optimize growth across the entire surface.

Why choose your lighting carefully for 2.88m²

With 2.88m² of grow space, you're entering the category of serious setups that can truly produce. But be warned: poorly lit, this space quickly becomes an energy sink with disappointing results. The rectangular shape of 240x120cm poses specific challenges. Corners are often the first to suffer from insufficient lighting, and the 240cm length can create significant intensity variations if not done correctly.

The calculation is simple: for optimal cultivation, aim for between 400 and 600 µmol/m²/s depending on the type of plants grown. For 2.88m², this represents a total need of 1152 to 1728 µmol/s. This is where the choice of technology becomes crucial. Modern LEDs offer the best energy efficiency with approximately 2.7 µmol/J, compared to 1.7 µmol/J for HPS. Concretely, where a 600W HPS barely covers this surface, a well-designed 400W LED easily does the job.

How to choose lighting for your 240x120cm space

First criterion: power. For 2.88m², count on 350W to 500W in LED, or 600W to 1000W in HPS. But power alone isn't everything. Light distribution is even more important over this area. A single central lamp will inevitably create less illuminated areas at the edges. The ideal? Two LED lamps of 200-250W each, positioned at 80cm and 160cm along the length.

Second crucial point: installation height. With LEDs, maintain 40-60cm between the canopy and the diodes. Too close, you risk light burn. Too far, you lose intensity. HPS require more distance (60-80cm) due to the heat generated. Also consider ventilation: 2.88m² under intense lighting gets hot. A minimum 400-500m³/h extractor will be necessary.

Finally, don't forget uniformity. Good lighting for this area should maintain less than 20% intensity variation between the center and the edges. Reflectors or LED optics play a major role here. Favor diffusion angles of 90-120° for homogeneous distribution.

Frequently Asked Questions

What lamp power do I need to cover a 240cm x 120cm space?

For 2.88m², aim for 350-500W in LED or 600-1000W in HPS depending on the desired intensity. For LED, a quality 400W is largely sufficient for productive cultivation. The calculation is based on 35-50W/m² for LED, compared to 60-80W/m² for HPS. Remember that the quality of the diodes matters as much as the power: Samsung LM301B or Osram LEDs at 2.7 µmol/J will be more efficient than generic diodes at 2.0 µmol/J.

Should I use a single powerful lamp or multiple lower-power lamps for this space?

Two lamps of 200-250W each outperform a single 500W lamp over this rectangular area. Light distribution will be much better, with fewer shaded areas in the corners. Position them at 80cm and 160cm along the length, centered on the width. This configuration also allows for more flexibility: you can adjust intensity by zone or replace a single lamp in case of failure. The initial cost is slightly higher, but the efficiency is worth it.

What is the difference between LED, HPS, and CFL lamps for this grow size?

For 2.88m², CFLs are clearly outdated – you'd need 8-10 125W bulbs, which is a nightmare to manage. 600-1000W HPS lamps generate a lot of heat and consume more, but remain effective for flowering. Modern LEDs dominate: less heat, adjustable spectrum, 50000h lifespan compared to 10000h for HPS. In terms of consumption, 400W LED is equivalent to 600-800W HPS in light performance. The LED return on investment is achieved in 12-18 months depending on electricity rates.

How do I properly install and position my lamp to avoid poorly lit areas?

Hang your lamps 40-60cm from the canopy for LEDs, 60-80cm for HPS. For 240x120cm, two fixing points at 80cm and 160cm along the length provide the best coverage. Use a lux meter to check uniformity: the difference between the center and the edges should not exceed 20%. If you only have one lamp, install it at the geometric center (120x60cm) and add side reflectors to redirect light towards the edges. Regularly check the height based on plant growth.

How many hours a day should I leave the lamp on and do I need a timer?

18h/day during vegetative growth, 12h/day during flowering – this is the standard. A timer is essential to maintain these cycles precisely. Plants are very sensitive to variations, even of 30 minutes. Invest in a reliable digital timer, not a mechanical model that can drift. For 2.88m² under 400W LED, count approximately 7.2 kWh/day during growth (18h) and 4.8 kWh/day during flowering (12h). At €0.15/kWh, this represents €1.08 and €0.72 per day respectively.