Low Heat Causing ( P) def

[shuggy4105]

Hi all
I hope everyone is growing their finest product and keeping themselves healthy in the mean time

I`ve moved house now and have recently set up and have some issues with the lack of heat in my grow room, thereby causing the phosphorus deficiency I`m seeing in all my ladies which are in week5 flow.
Still using 400w HPS whilst growing Super Skunk and one White Widow given by a friend to grow out while they holiday. Feeding them 'sensi bloom ph perfect' cal/mg along with 'Vitalink bloom' I think its called, but I use a wide range of products to try and vary the nutrient range. I`m in soil btw with ph of 6.5-6.8.
I already purchased a greenhouse heater which raised the temps by one degree only so then introduced a couple of heat pads to try and keep the root zone warmer which should enable the plants to withstand a lower temp, but this deficiency is sticking around. I'm running the lights at night so as to have the day temps as my night period but still its cold here in bonny S even in the day...
Any suggestions? its an attic space, segregated off partly, which I have insulated as much as possible. The entire space is about 30ft by 15ft but the grow space is only around 9x9. I`m thinking Calor Gas fire but worry about fire risk etc.
Thanks in advance kinsmen!:icon_smile:

 

[shuggy4105]

sheet I almost forgot. Temps are sitting at around 55f night period and only 64f day...

 

[shuggy4105]

What deficiencies am I likely to see in the latter half of flower if these temps persist? I'm monitoring some other things at the moment but too early to tell on them. Also, I added a space heater however it runs 1800-2100w which is absolutely unacceptable with the cost of electricity on this island. My issues have always been at the opposite end of the spectrum with too much heat! so this is all new to me. I feel like a newb again lol.

 

[Melvan]

How about moving up to a more powerful light? You're running a 400w, even a 600 would add additional heat, and not pull power like the space heater.

You can get a newer ceramic type heater that doesn't pull anywhere near the same juice, and is also programmable so it only runs until its up to temp. Something along the lines of this.

hXXp://www.lowes.com/pd_81525-33454-DCH5090EL_0__?storeNumber=2284&selectedLocalStoreBeanArray=%5Bcom.lowes.commerce.storelocator.beans.LocatorStoreBean%401a541a54%5D&productId=3262237&ipTrail=50.120.98.148

 

[nouvellechef]

I would also get a larger light and unduct it. Rather use the heat from a 1000 watt light to keep things warmer during lights on hours and reap the benefits of a larger harvest than pay for kilowatts on a electric heater. Basically paying the same money out give or take, for way less yield. I will say though, I have never worried too much about temp swing. In dead winter I will buy temp swings with no negative results.

 

[The Hemp Goddess]

If you got your space smaller, it would be easier to heat also. A 400W light is only good for about 9 sq ft. A 81 sq ft space is going to be hard to heat without a large wattage space heater. In an attic space, even a 1000W is going to have a hard time producing enough heat in a space that large.

 

[shuggy4105]

Thanks for the quick response. I'm looking into a different heater with a controllable thermostat so thanks for that link Melvan.
HempGoddess, I've insulated the 9x9 space I use for growing to the best of my abilities at this time for reasons I can`t really go into so maybe a radiator or alike is the way to go.
Nouvellechef, I would like to increase the wattage at some point but in order to get this crop wrapped up I`m stuck with what I have for now. you don't experience (P) def with those low temps as I`d mentioned?
Thanks again, food for thought...

 

[nouvellechef]

No. Ever since I started amending the soil with 1.5cups per cubic foot of medium with fine grade dolomite lime, I have not seen anything in years.

That last set of pics I posted in my journal. Last week or so the low at dark hours is about 48.

 

[chazmaine420]

You didnt mention what type of lamp your using. Is it an air cooled hood? I've just started to return the hot air duct into my room and its around 80 degrees in there with a 600 watt HPS.

 

[ozzydiodude]

I've never seen anything connecting temps and nutrient up take. Slower growth with lower temps yes.

 

[sunakard2000]

:yeahthat: as ozzy said iv never seen or heard of temps having any corrilation to nute uptake, pH would be the biggest factor in nute uptake problems. so either your pH is off and not allowing P to be taken up, or if your using chemical salt cleated nutes you could have some salt build up in the root zone thus blocking nute uptake, OR the 3rd option, simply the plant wants more P then you are feeding it.
from what iv read and heard from friends the 2 strains you are growing are far opposites in how much they eat, WW as with most white strains is typicaly a light feeder, and Skunks tend to be heavier feeders, so that could be it too, if you were feeding say X strength which was perfect for the WW it could be too weak of strength for the skunk. good idea to mix up nutes in different batches for each strain as each strain will have different needs in terms of how much or little they need.
well thats my 2 cents on that.

 

[Growdude]

From mjp:
This picture is caused by temperature changing from cold to warm, cold nights and warm days.

Some varieties, like equatorial sativas, don't take well to cold weather. If you can keep the roots warmer, the plant will be able to take cooler temps than it otherwise could. Also note that in colder temps, phosphorus gets poorly absorbed and if this happens your plants can show purpling of the leaves and stems, (cannabis has a natural purple color to it's stems, the deep purple is what shows the problem)this is the same example when plants change color in flowering when environment triggers cause the plant to change color, also genes play a role as well.

 

[Hushpuppy]

I had that very thing happen to me when I first started my "stealth cabinets". I had 2 Blueberry Punch clones that were bushing up nice in hydro when my temps get below 60f with lights on and they began to look exactly as the pic above. Once I got my rez temps up to 70f and air temps during lights on in the mid 70s, I had no more issues like that.

 

[7thG]

I would try to enclose your grow space, whether it be a tent or a DIY box. Then the temp should be much easier to control with your light setup.



I found this on YouTube awhile back I thought it could be useful to the right person.

hxxps://www.youtube.com/watch?v=nzKbFzUEWkA

 

[shuggy4105]

I had no idea myself until recently about the temperature effect on nutrient uptake, especially in respect of cold but I`m finding out that's for sure!
I`ve placed a 750w radiator inside the grow space which has raised the temps to mid 70s so I`m happy with that for now.
its an air-cooled reflector, no ducting whatsoever so all heat already directed to the space...Thank you to all who responded and the useful links, very much appreciated

 

[oldsman]

This is my last little one left from outside season.She has seen some fairly cool nights,low to mid 40's.It takes a couple nights of cool temps before they'll show def.This one got neglected a little as I was busy harvesting others.I'll try to give her a few more weeks but low temps will be in low 30's next couple nights,might do her in.A cool night once in a while doesn't harm them,but 3-4 cool nights in a row might.