When to start seedlings in Greenhouse using natural light?

[Blew Hiller]

Looking to grow White Widow Female and Northern Lights Auto...first time grow for both. We have a passive solar greenhouse with aquaponics. We use fans to move the air through the floor (thermal mass) which minimizes the heat deltas and (hopefully) minimizes detrimental humidity issues.

So here's my question: I am @44'N which gives me 13/14 days in May, June, July, August. (12 hour days occur in Sept.)

When do I start seedlings? Is there such a thing as too early? I've read where autos want more than 12/12, but the regular females want 12/12...correct? Start one strain before the other?

Thoughts & advice appreciated.

 

[Fuzzy Duck]

12/12 is just an associated timing for growing indoors under lighting with regular or feminized seeds.

Autos are really not that fussy most of time indoors peeps will more likely use 18/6 from start to finish.


So ya really don't want to get indoor concepts to mixed up with out door.

Another thing is cannabis can start to flower under 14 hours of day light Ed Rosenthal wrote some thing about this vs true indica & sativa flowering times.

I'd settle for May myself providing night time temps are not to low in the green house, autos ah well that one might finish quicker than the other tho as some suggest autos are great for the shorter seasons in some places in the world.

Not to sure if i've seen an auto out door grow journal yet ? some one might post a link...

 

[Cannoisseuras]

Depending on temp I would say around early may

anything that occurs in nature cannot be unnatural!
The Birth & Evolution Of A Dragon

Unknown Strain From Seed - First Time Grow

 

[Blew Hiller]

How low is too low temp @ night? Also concerned about high temps since it can easily get to 90-95F if not properly vented. So the autos will bud on their own at some predetermined time irrelevant of daylight hours? I bought fem and auto just to experiment with the growing conditions in my area. Thanks for the feedback.

 

[Fuzzy Duck]

Most will say temps below 16 c / 60 f will stunt growth.

So providing your night temps in the green house are not below this you are reasonable fine, mmm 90/95 f might be a problem ? i just think about out side conditions in the world where peeps may grow out side may well go over this...


I don't think any of this is a problem when simple tricks may help out.


Sounds like you have pretty cool green house to me i wish i had one like that

Keeping night time temp up, well you could use a paraffin heater to raise temps but will be daily job for a short time that is the easy option or a horticultural white fleece to cover them up at night will help protect them as well by a few or so celcious.

Other wise it is electrical heating like oil filled radiators you can get bar type ones fashioned like a large pipe i'm not sure if they come with thermostats tho ?

Dealing with summer temps in the green house, well you always have the classic white wash stuff applied to the out side that will help a bit but other materials can be used which come as fabric sheeting this will require further research tho !


What i found interesting was from the first post...

We use fans to move the air through the floor (thermal mass) which minimizes the heat deltas.

To me that sounds like you using the ambient temp of air to heat the thermal mass which stores heat & slowly releases it during the cooler night period.

Seen this done with rocket mass heaters in bio domes the thermal mass was sand which stores heat pretty well.



Ye you got an interesting grow environment, you making think about a hell load of stuff right now

Back to the green house, well passive window venting most will have these all done by hand most the time but you can get self opening green house vents which may well help out with temp control... yup more home work !


Well Blew you are certainly interesting & indeed a rare pleasure to offer some help here or their... ever thought about keeping a grow journal

 

[Blew Hiller]

Low temps = stunted growth. Good to know.

We have two (2) passive solar greenhouses (GH), one small (10x24') and one larger (16x48'). Their design is a hybrid of several different ideas: We use the day heated hot air to warm the crushed rock thermal mass (70,000 lbs worth!) and this then continues to release its heat into the cooling overnight air. Come morning, the cooled thermal mass begins to once again absorb the heat...which in turn cools the hotter day air inside. I have an interesting chart where we plotted a lot of the first winters data...not sure how to upload a photo on this thread. Structurally, the GH are wood framed with an angled south facing tripled walled polycarbonate light wall.

Back to your advice...doubt I can keep the GH above 60 until at least end of March. i have seen some videos online where people try to get a head start by using artificial lights and then transplant outdoors. It appeared they were trying to maximize the vegetative growth which, presumably, would produce more buds. Accurate? This was genesis of my initial thought of starting early and if there was any merit to that.

 

[Fuzzy Duck]

This will help - Photo Gallery Guide - How to Resize, Upload & Post Photos

Some growers will start out indoors under lighting metal halide, cfl, T5 or 8 tubes 6500 k etc to bring on the plants before going out doors & then it is a case of hardening them off for out door life. In theory starting them off indoors will bring on better developed plant than waiting in till ideal times later in the year for seed germination out doors or just very careful timing / transition if using both methods.

Whether starting early on indoors will = more yield is hard to say for pure out doors to a glass house is hard to say when environmental conditions may well effect over all results in the long run... out doors you have to contend with weather conditions through out the year which may effect things plant wise a GH is just a micro environment really which you may use to bring on plants early before going out doors or lengthen growing periods early/late etc

Yup regular or feminized seed is fine to bring on early, i'm not to sure about autos though which might be better to leave in till a month later ?

To nurture for cannabis is understanding the favourable growing conditions it so wishes to thrive in for good results !


I understand temps are still low in March, i look after a couple of very old style GH's & poly tunnel at work with several thousand bedding plants arriving late March for growing on, i understand.



Random stuff...

Might be able to section off a part of the GH with bubble wrap etc to create a micro climate for a couple of plants & if the solar panels produce enough electric too power additional heating you might be on to some thing, i'm not overly sure about night time temps tho but that may mean an external source of power too keep em happy, i'd still put a safe bet on a paraffin heater tho in less ya got your self some long extention cables.

 

[Bapple]

I would start both of them beginning of April at your latitude, because the Auto needs good Spring heat to get a good fast veg going.

If final size and height are not an issue the Photo will have a long leisurely veg and you'll harvest a monster in September. You could grow them both really big in that greenhouse.

Look forward to following the grow.

 

[Blew Hiller]

FuzzyD - Thanks. I uploaded some pics t my Member Gallery so it that easy enough to link off my id or do I need to link it?

Your "random stuff" is exactly along a similar thought I had. Inside the GH we have 700' of 4" drainage pipe embedded in the thermal mass. Fan at one end of the GH pulls hot air down from 8' high and pushes it through 16 equal lengths of the drainage hose in the ground rock. The most consistent temps are at the immediate exit points of those pipes...so I was thinking of making a box of scrap polycarbonate which gets fed the constant air from one or more of these pipes. I'll do that and get a read on the day/night temps before I move ahead.

 

[Blew Hiller]

Bapple - April sounds good and I am going to try to eek an extra month with a seedling incubator within our greenhouse. Been wanting to try it in the past so now is a good time.

Also...please define Photo. Thanks

 

[Bapple]

Your White Widow is a feminised Photoperiod .....we abbreviate it to Photo......like Auto really means Autoflowering....

When I used to garden in the UK, I had a south facing conservatory and would start my chilli seeds in the airing cupboard and then move them into the Conservatory as they sprouted.

 

[Blew Hiller]

Bapple - I'm hoping that I can combine the constant temps, air flow, and available sunlight in a custom incubator box. Stay tuned.

Thanks also for the clarification of Photo. So can an Auto also be a Photo? Any glossary here on 420?

 

[uptheholler2]

With an outdoor autoflower the goal most folks have is to harvest as early a crop as possible and still maximize yield. I have always figured that while some autoflowers can begin to flower at 14 to 21 days most just begin to show pistols in that time frame. So for outdoors I start seeds about 20 days before the USDA last frost date . I have been pleased with both flower formation and quality. In my area I can usually harvest by late June or early July. Best of luck in all you grow

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[Blew Hiller]

UptheHoller2 - I ordered both varieties because I wanted to see which performed best under my local conditions. So if I started both the Auto and the Photo at the same time (say March under controlled conditions) the Auto would yield that much sooner than the Photo ?

thanks.

 

[uptheholler2]

Yep I currently have 2 auto flower varieties just beginning to show pistols. Germinated on Feb 3rd...so 20 days ago. I have reg photoperiod plants started and germinated around the same time. Should harvest autos in mid April or a little earlier. Photoperiods early to mid June. Some may go till July. Depending upon veg time.

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[Blew Hiller]

Good info. In your last sentence you say "depending on veg time". Will this be via controlled indoor lighting? If so, how would that translate differently using standard outdoor summer daylight? Will the photo wait till 12/12 days in Sep to flower?

Thanks.

 

[uptheholler2]

Yep I start all of my plants either indoor under artificial light or out in the greenhouse. Then I transplant outside or just finish them inside as conditions warrant. Most varieties begin to flower way before you hit 12 -12. Remember days start getting shorter on after June 21st. Ive had photoperiods that begin to show sex in the second and 3rd week of July. They sense the shift slowly at first and then eapidly pick up the pace as temps begin to cool

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[Blew Hiller]

Good info. Thanks.

 

[Bapple]

Bapple - I'm hoping that I can combine the constant temps, air flow, and available sunlight in a custom incubator box. Stay tuned.

Thanks also for the clarification of Photo. So can an Auto also be a Photo? Any glossary here on 420?

No an Auto cannot be a Photo. Autoflower strains have been bred with Ruderalis in them and that is why they are more expensive. Photoperiod seeds are regular marijuana the way it comes.....

 

[Blew Hiller]

Good info. Thanks.