# Room size to light ratio question **URL:** \ **Category:** Grow Cycle\ **Created:** [March 18, 2017, 12:23pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818 "2017-03-18T12:23:16Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![McLovin](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/mclovin/32/36324_2.png) [@McLovin](https://ilgmforum.com/u/McLovin)\ **Post date:** [March 18, 2017, 12:23pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/1 "2017-03-18T12:23:17Z")
Hello everyone… i have a question .last year i built a 4 X 7 X 7 grow room and grew 4 white widow and 2 blueberry plants under cfls. I just upgraded my lights to 2 600 watt hid. My question is how many plants should go under each light. I heard i will get about the same yeild with. 3 plants as i would with 6 plants under the same light. I was planning on growing 12 plants (state maximum) will the 2 600 watt hps be enough or should i invest in another light? Thanks in advance ---
**Author:** ![Niala](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/niala/32/86871_2.png) [@Niala](https://ilgmforum.com/u/Niala)\ **Post date:** [March 18, 2017, 12:39pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/2 "2017-03-18T12:39:42Z")
You need a minimum of 1400 watts of lights to cover all your grow space area , so invest in another HID light, you’ll be happy and so your plants 😆. However, HID lights produce much more heat than CFL., so vented hood are a must with appropiate ventilation and exhaust system. Even if you decide to stick with 2 HID lights. That’s more investement. Hoping that’s helping you @McLovin, do not hesitate to ask more questions if you need to 😀 ~Al 😇 ✌ ---
**Author:** ![McLovin](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/mclovin/32/36324_2.png) [@McLovin](https://ilgmforum.com/u/McLovin)\ **Post date:** [March 18, 2017, 1:57pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/3 "2017-03-18T13:57:34Z")
Thanks for the help. I actually have 6 white widow in 2nd week of flowering stage right now under the 2 600 watt hps.They all seem to be loving the lights.just got my california dream in the mail yesterday hope to start veg soon with them. I am a new grower . The California dream will be my 3rd grow. So i am sure i will annoy everyone with lots of questions. Definitely going to get another hid and exhaust before i start my next grow. Thanks again ---
**Author:** ![Niala](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/niala/32/86871_2.png) [@Niala](https://ilgmforum.com/u/Niala)\ **Post date:** [March 18, 2017, 2:06pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/4 "2017-03-18T14:06:57Z")
You’re welcome 😇 ~Al ✌ 😇 ---
**Author:** ![Matthew420](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/matthew420/32/24589_2.png) [@Matthew420](https://ilgmforum.com/u/Matthew420)\ **Post date:** [March 18, 2017, 5:19pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/5 "2017-03-18T17:19:20Z")
The formula is 50w of light per square foot, which is the 1400w @Niala suggested. ---
**Author:** ![McLovin](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/mclovin/32/36324_2.png) [@McLovin](https://ilgmforum.com/u/McLovin)\ **Post date:** [March 18, 2017, 5:51pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/6 "2017-03-18T17:51:38Z")
@Niala @Matthew420 thank you both. I have “HIGH” hopes for my next grow. ---
**Author:** ![Niala](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/niala/32/86871_2.png) [@Niala](https://ilgmforum.com/u/Niala)\ **Post date:** [March 18, 2017, 6:09pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/7 "2017-03-18T18:09:14Z")
You’re welcome @McLoving ---
**Author:** ![McLovin](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/mclovin/32/36324_2.png) [@McLovin](https://ilgmforum.com/u/McLovin)\ **Post date:** [March 23, 2017, 1:48am UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/8 "2017-03-23T01:48:29Z")
Ok so i will have 3 600 watt mh/hps in my grow room. My question is … Will i get the same yeild from 6 plants as i would growing 9 plants. Using the same amount of watts per square foot? ---
**Author:** ![Niala](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/niala/32/86871_2.png) [@Niala](https://ilgmforum.com/u/Niala)\ **Post date:** [March 23, 2017, 2:08am UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/9 "2017-03-23T02:08:40Z")
Do not forget that light penetration is one of the most important key for a high yielding , so, more crowded is your growing space, more lumens, more light you’ll needed ---
**Author:** ![McLovin](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/mclovin/32/36324_2.png) [@McLovin](https://ilgmforum.com/u/McLovin)\ **Post date:** [March 28, 2017, 12:10am UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/10 "2017-03-28T00:10:53Z")
How far away should the tops of my plants be from my 2 600 watt hps… i have heard as low as 16 inces to 4 feet… thats a huge difference . I had them at 18 inches but i started to get heat stress so i now have them at 24 inches. I use 2 ipower 600 watt hps with standard wing reflectors . 18 inch fan blowing across the tops of plants. No exhaust temps between 68 during dark hours and 78 during light And my lights are wing to wing . Should i spread them out. Thanks ---
**Author:** ![Capt\_Seeweed](https://sea2.discourse-cdn.com/growingmarijuana/user_avatar/ilgmforum.com/capt_seeweed/32/55942_2.png) [@Capt\_Seeweed](https://ilgmforum.com/u/Capt_Seeweed)\ **Post date:** [April 17, 2017, 3:08pm UTC](https://ilgmforum.com/t/room-size-to-light-ratio-question/9818/11 "2017-04-17T15:08:50Z")
@McLovin just wondering how your California Dream grow is going… I started two CD plants a few weeks ago and would like to know what to expect…