Really weak stems???

I have six plant under a 400 watt HPS Temp is 72-78 while lights are on and 64-69 while lights are off . They look real healthy but if i dont hold them up by building the soil up around them they fall over well three of them at least any ideas of what caused this and what i can do to fix it? here are some pics of the plants .

How old are they? put a fan on them that will help alittle.

they haved been in there two weeks thursday and i alreadty have two six in fans on them . thanks for the reply

a nutrient deficiency can cause week tissue structure, also if there is no nutrient problem then it could be root rot, or bugs eating your roots. How far away is the light, too far away and they will stretch out too far causing them to fall over, once some of mine grew to long and fell over, I just left them and they eventually turned up.

First off how far away are your lights? your plants could be streching towards the light inorder to recieve enough light thus causing them to have weak stems. Second, do you have a fan in your grow area? A fan acts like the wind would in nature and the gentle sway increases your plants stem strength.

I know it's hard to keep your HPS too close to your plant, so your plants will stretch a little bit when it's vegging. Just give it a little support using chopsticks or something at the initial stages of growth. It will be able to support itself a bit later in growth. Also, a little air movement around the plant allows for strengthening of the stems. Don't have a fan blowing directly at it, but indirectly, such that the plant vibrates gently.

I wouldnt worry, yet. if it doesnt get thicker in a week or so then i would worry.

are the fans blowing air blowing it at the plants directly?

darkdestruction420 said:

are the fans blowing air blowing it at the plants directly?

Click to expand...

get an osilating fan they work perfect