Light height

I have a single 1000-watt and two 400-watt HPS lamps, as well as two four-foot, two-tube fluorescent fixtures. How far above the plants should I hang the lamps?
Chief NastyNug,
Nixa, Missouri

Under most circumstances a 1000-watt lamp with no shield should be kept no less than two feet from the top of the canopy. A 400-watt lamp can be placed as close as 15 inches. A fluorescent tube can be placed about six inches from the top of the plant.

The distance is not to protect the plants from the lamp’s brightness, but from the heat that it generates. At its peak, the Sun is brighter than even 1000-watt lights. The amount of light measured 24 inches directly under a 1000-watt horizontal HPS lamp with high efficiency reflector measured about half of what a plant would receive at noon on a cloudless day in early July at the 38th parallel. It would equal the light intensity of a September day at noon, when the flowers are ripening. There was fall-off as the meter was moved from the center.

Heat from the lights causes the buds to “run.” Instead of blocky buds on compact stems, the branches stretch and new growth appears, with thin groups of flowers. There are several ways to deal with the heat. Swift circulation/ventilation systems can be set up to move heated air away from the canopy and out of the area. This works best when there is a constant source of cool air. For instance, in Holland, which has cool air most of the time, heated air is replaced with a constant flow of filtered street air. In large spaces the air draft results in a low roar of white noise.

Another method of dissipating the heat is to use a light mover. The heat is radiated to any point for only a few moments. The mover disperses both light and heat. With a reasonable circulation system, the heat is variable, but not intense.

By far the most efficient method of eliminating the heat, enabling the lights to be placed closer to the plants, is by using air-cooled lights. The lights are enclosed by the reflector, which holds a glass plate that captures most of the lamp’s heat. Using 4-inch duct tubing powered by an inline fan, the lights draw in cool air from outside the space to cool the light. Heated air is pushed out through the exhaust duct on the other side of the reflector. This air has never been in contact with the garden. It has no odor, just heat. It can be used to heat a space or just vented to the outdoors.

With air cooling, a 1000-watt lamp can be placed at 15-18 inches from the top of the canopy and a 400-watt lamp can be placed about 12 inches above it.

Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA
You can also email Ed at [email protected], and send queries via his website at
All featured questions will be rewarded with a copy of Ed’s Marijuana Question? Ask Ed. from Quick Trading.
Sorry, Ed cannot send personal replies to your questions.



  1. Pingback:

  2. Pingback:

  3. Pingback: best free porn sites

  4. Pingback: buy gynexol

  5. Pingback: nike air force 1 white

  6. Pingback:

  7. Pingback: escorts madrid

  8. Pingback: crypto currency

  9. Pingback: black seed oil

  10. Pingback: Personalized Video From Santa Claus

  11. Pingback: instagram porn sale

  12. Pingback: pof premium apk

  13. Pingback: best porn site

  14. Pingback: Gunnar Andreassen webdesign

  15. Pingback: porn sites

  16. Pingback: porn sites

  17. Pingback: spin io

  18. Pingback: Flights to London Stansted STN

  19. Pingback: steel trivet

  20. Pingback: homemade porn sites

  21. Pingback: 陰道變鬆

  22. Pingback: wholesale iphone cases

  23. Pingback: swivel hanger clip

  24. Pingback: 2018 Porsche 991.2 GT3 Armytrix Titanium muffler

  25. Pingback: Boonswang SEO

  26. Pingback: vip financial education

  27. Pingback: anthony morrison

  28. Pingback: satin al

  29. Pingback: louboutin melbourne

  30. Pingback: anthony morrison

  31. Pingback: dog subscription box

  32. Pingback: Nunti in constanta

  33. Pingback: michael kors outlet

  34. Pingback: joanns coupons

  35. Pingback: Progressive life insurance quotes

  36. Pingback: eico Insurance

  37. Pingback: google blackhat free

  38. Pingback: mk outlet australia

  39. Pingback: hacklinks

  40. Pingback: walmartone

  41. Pingback: moms chips

  42. Pingback: couples gifts

  43. Pingback: buy viagra online

  44. Pingback: pirater un compte facebook

  45. Pingback: WoW Vanilla discord

  46. Pingback: walmartone

  47. Pingback: Jumbo Antep Fıstığı

  48. Pingback: walmart1

  49. Pingback: porn city

  50. Pingback: dentistry in el cajon

  51. Pingback: High chair cover

  52. Pingback: loft bed singapore

  53. Pingback: cataluña es españa

  54. Pingback: Peter Schatzberg

  55. Pingback: pornmd

  56. Pingback: mspy

  57. Pingback: additional resources

  58. Pingback: berita global

  59. Pingback: scholarship essay

  60. Pingback: vidfox

  61. Pingback: describes it

  62. Pingback: Homepage

  63. Pingback: اغاني عربية

  64. Pingback: college application essay

  65. Pingback: Los Angeles Web Design

  66. Pingback: Arvind Pandit

  67. Pingback: computer equipment disposal

  68. Pingback: old it disposal

  69. Pingback: House of Eros Red Leather Double Loop

  70. Pingback: Comment Grandir Naturellement a Tout Age Gratuit Pdf

  71. Pingback: walmartone

  72. Pingback: Bitcoin

  73. Pingback: read what he said

  74. Pingback: news live

  75. Pingback: iTunes

  76. Pingback: duvporn

  77. Pingback: Agnes

  78. Pingback:

  79. Pingback: Diet

  80. Pingback: Berdion de Crudo

  81. Pingback: دانلود فیلم رگ خواب

  82. Pingback: Google spam tactics

  83. Pingback: avakin life hack android

  84. Pingback: what is mlm company

  85. Pingback: دانلود فیلم رگ خواب

  86. Pingback: zenofem reviews

  87. Pingback: www.consumerhealthdigest

  88. Pingback: marks and spencer coupon

  89. Pingback: menoquil review

  90. Pingback: prostara review

  91. Pingback: Oddsmonkey

  92. Pingback: Oddsmonkey

  93. Pingback: Oddsmonkey

  94. Pingback: Oddsmonkey

  95. Pingback: Oddsmonkey

  96. Pingback: kitchen cooking

  97. Pingback: best slot machines to win on

  98. Pingback: ΚΟΥΠΟΝΙ ΣΤΟΙΧΗΜΑ

  99. Pingback: buy hacklink

  100. Pingback: ATHENS HOTELS

  101. Pingback: my site check here

  102. Pingback: go here to seee the asite

  103. Pingback: پنجره

  104. Pingback: Taruhan Olahraga

  105. Pingback: فیلم نهنگ عنبر

  106. Pingback: porn movie

  107. Pingback: xxx mobi

  108. Pingback: game hack

  109. Pingback:

  110. Pingback: Sang Kutu Bola

  111. Pingback: Deal Feed

  112. Pingback: Taruhan Olahraga

  113. Pingback: Schluesseldienst

  114. Pingback: link

  115. Pingback: SkinAlley

  116. Pingback: Shopping cart cover

  117. Pingback: gosexy

  118. Pingback: Limo Rental Vancouver BC

  119. Pingback: real caller apk

  120. Pingback: baby shower gift ideas

  121. Pingback: دانلود فیلم نهنگ عنبر

  122. Pingback: stroller accessories

  123. Pingback: headhunter

  124. Pingback: دانلود سریال شهرزاد فصل دوم

  125. Pingback: دانلود فیلم دوبله شده

  126. Pingback: دانلود آینه بغل

  127. Pingback: پنجره کرج

  128. Pingback: he said

  129. Pingback: پنجره

  130. Pingback: aries man in love with me

  131. Pingback: click terminal

  132. Pingback: Judi Online

  133. Pingback: Private Tour

  134. Pingback: youtube video

  135. Pingback: physics solution manual

  136. Pingback: Judi Online

  137. Pingback: google leaks

  138. Pingback: vehicle shippers

  139. Pingback: دانلود فیلم نهنگ عنبر 2

  140. Pingback: vape mods

  141. Pingback: Easiest Way To Make Money Online

  142. Pingback: recruitment

  143. Pingback: Watch movie for free

  144. Pingback: Judi Online

  145. Pingback: Bad Credit Remortgages

  146. Pingback: read now

  147. Pingback: real estate theme wordpress premium

  148. Pingback: garden

  149. Pingback: دانلود فیلم

  150. Pingback: download

  151. Pingback: Cash Offer

  152. Pingback: download movie

  153. Pingback: دانلود

  154. Pingback: دانلود فیلم

  155. Pingback: steel chips dip bowl

  156. Pingback: karaj

  157. Pingback: kitchen tools stainless

  158. Pingback: real casinos online

  159. Pingback: صيانة

  160. Pingback: 192 168.0 1 alterar senha wifi

  161. Pingback: gay porn

  162. Pingback: vlogging camera

  163. Pingback: picture

  164. Pingback: usi tech presentation

  165. Pingback: slimming pants

  166. Pingback: gardening

  167. Pingback: Finger Family Song

  168. Pingback: top 40 music

  169. Pingback:

  170. Pingback: Seo

  171. Pingback: پنجره دوجداره

  172. Pingback: EVA TV

  173. Pingback: atualizado

  174. Pingback: پنجره

  175. Pingback: پنجره دوجداره

  176. Pingback: Web Design Yakima

  177. Pingback: award winning movie

  178. Pingback: have a peek at this web-site

  179. Pingback: heartland dental care

  180. Pingback: Data Logger

  181. Pingback: window

  182. Pingback: ed sheran

  183. Pingback: walmart1 login

  184. Pingback: stainless steel shower head

  185. Pingback:

  186. Pingback:

  187. Pingback: site web

  188. Pingback: garden bridges san francisco

  189. Pingback: مشاوره بازاریابی اینترنتی

  190. Pingback: Weed Shop

  191. Pingback: google hd porn

  192. Pingback: پنجره دوجداره

  193. Pingback: اموزش ساخت پنجره دوجداره

  194. Pingback: پنجره دوجداره

  195. Pingback: gernas kids

  196. Pingback: پنجره دوجداره

  197. Pingback: دانلود

  198. Pingback: پنجره دوجداره

  199. Pingback: gratis annonser dk

  200. Pingback: پنجره

  201. Pingback: پنجره

  202. Pingback: دانلود فیلم ایرانی

  203. Pingback: پنجره دوجداره

  204. Pingback: Pay Per Click Belfast

  205. Pingback: fast loans uk

  206. Pingback: mon id�e

  207. Pingback: Limo Service Vancouver BC & Party Limos Bus Vancouver BC

  208. Pingback: free delivery codes

  209. Pingback: callaway x2 hot driver australia

  210. Pingback: make money online

  211. Pingback: شرکت تولیدی پنجره دوجداره

  212. Pingback: دانلود

  213. Pingback: قیمت پنجره دوجداره

  214. Pingback: پنجره ضد سرقت ایرانی

  215. Pingback: دانلود فیلم

  216. Pingback: فروش توری پنجره دوجداره

  217. Pingback: آموزش ساخت پنجره دوجداره

  218. Pingback: پنجره دوجداره ویستایست

  219. Pingback: Marquees London

  220. Pingback: game

  221. Pingback: guia consulta cpf

  222. Pingback: political polls twitter

  223. Pingback: Best Crib Mattress

  224. Pingback: دانلود

  225. Pingback: 食品

  226. Pingback: دانلود سریال عالجناب اول

  227. Pingback: دانلود فیلم ایرانی

  228. Pingback: دانلود سریال عالیجناب قسمت اول 1

  229. Pingback: دانلود شهرزاد قسمت 16

  230. Pingback: 16 دانلود سریال شهرزاد

  231. Pingback: youtube

  232. Pingback: Kasha

  233. Pingback: Roof Repair Long Island

  234. Pingback: blazing key

  235. Pingback: ΤΣΑΝΤΕΣ TRUSSARDI

  236. Pingback: Social Media Marketing

  237. Pingback: Accounting firms in chicago

  238. Pingback: clash royale gems tool

  239. Pingback: دانلود سریال شهرزاد قسمت 15 پانزده

  240. Pingback: anime

  241. Pingback: titleist 917 driver

  242. Pingback: vpm

  243. Pingback: nico control � bom

  244. Pingback: دانلود قسمت هشتم شهرزاد دوم

  245. Pingback: la home

  246. Pingback: DraftKings DFS

  247. Pingback: coin-banks bitcoin

  248. Pingback: My Homepage

  249. Pingback: bitcoin trading

  250. Pingback: brief boxer gay

  251. Pingback: پنجره دوجداره

  252. Pingback: clash royale gems tool

  253. Pingback: video gaming

  254. Pingback: cliquez ici

  255. Pingback: dick

  256. Pingback: compare hotel prices website

  257. Pingback: Roof Repair Long Island

  258. Pingback: casino games usa

  259. Pingback: دانلود قسمت ششم شهرزاد دوم

  260. Pingback: groin support

  261. Pingback: دانلود موزیک

  262. Pingback: Facial Spa Services Hollywood

  263. Pingback: Facial Spa Services Cooper City

  264. Pingback: Facial Spa Services Oakland Park

  265. Pingback: دانلود قسمت هفدهم عاشقانه

  266. Pingback: شرکت تولیدی پنجره دوجداره

  267. Pingback: فروش پنجره دو سه جداره

  268. Pingback: دانلود سریال عاشقانه

  269. Pingback: پنجره دوجداره وین تک

  270. Pingback: ساخت پنجره دوجداره

  271. Pingback: porno gratis

  272. Pingback: videos porno

  273. Pingback: videos porno

  274. Pingback: porno

  275. Pingback: videos porno

  276. Pingback: videos porno

  277. Pingback: porno

  278. Pingback: porno gratis

  279. Pingback: videos porno

  280. Pingback: porno gratis

  281. Pingback: Admission via Good Donation in any medical college

  282. Pingback: porno

  283. Pingback: ping g30 driver australia

  284. Pingback: دانلود قسمت اول فصل دوم شهرزاد

  285. Pingback: nba jerseys melbourne

  286. Pingback: bypass windows 7 admin password

  287. Pingback: دانلود قسمت یازدهم شهرزاد دوم

  288. Pingback: دانلود ققسمت 12 عاشقانه

  289. Pingback: دانلود قسمت پنجم شهرزاد دوم

  290. Pingback: Loyola College for Sale

  291. Pingback: دانلود سریال عاشقانه

  292. Pingback: popular online twshows

  293. Pingback: Paleo Diet

  294. Pingback: April O'Neil

  295. Pingback: دانلود قسمت هفدهم عاشقانه

  296. Pingback: دانلود قسمت دهم فصل دوم شهرزاد

  297. Pingback: دانلود قسمت ششم فصل دوم شهرزاد

  298. Pingback: lesbian sex

  299. Pingback: قیمت پنجره

  300. Pingback: دانلود شهرزاد قسمت نهم فصل دوم

  301. Pingback: دانلود شهرزاد قسمت هفتم فصل دوم

  302. Pingback: دانلود قسمت هشتم شهرزاد دوم

  303. Pingback: دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2 دوم 2aaadffdsvc

  304. Pingback: alcohol abuse treatment

  305. Pingback: دانلود رایگان قسمت 8 هشتم سریال شهرزاد فصل دوم 2

  306. Pingback: 4cyn5et4m5t94c5t9m4vn54cx65

  307. Pingback: Under Canopy Lighting Cannabis

  308. Anonymous on

    k i have a 150 watt light it will do for now, first time growing. i want to kno wats the right height i shud move the light up with the plant. 12 inches? more or less? one of the plant leaf looks like its folding a bit wats that a sign of? thx