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Ask a Grower

Ask-a-Grower #94

How many watts of light do I need per plant? I’m trying to use florescents.

Watts- per- square- foot is easy to calculate but is not a good way to determine usable light for a garden. Most growers use fluorescent to grow clones and small vegetative plants and maintain mother plants.

Most growers prefer high- wattage lamps- 400, 600, 1000 watts because of the lumens per watt and their PAR rating is high then smaller bulbs such as fluorescents. The goal is to get at least 10,000 lumen or more to each plant. Light intensity is more important when considering lighting. When light intensity is low, plants stretch for it. Low light intensity often caused by the lamp being too far away from plants. Dim lights or lights without enough lumen cause sparse foilage. The easiest way to think about it is when you are growing plants you will need about fifty watts of HID lighting per foot.

This assumes that your garden is square, try to use this as a principal.

1 250 watt two foot by two foot garden.
1 400 watt for a three foot by three foot garden.
1 600 watt for a 3.5 foot by 3.5 foot garden.
1 1000 watt for four foot by four foot garden.

We hope this helps you out and look forward to answering any questions you may have in the future.