Can't use a grow light for seedling stage before moving outdoors in semi cold climate, what should I do?

I have some questions about germination and seedling stage, because where I live there are two factors which are throwing me off a bit:

  1. Spring starts in September where I live, but we have chance of frost up until early November.

  2. I also can’t use lights indoors. Otherwise this would be a lot easier.

So I plan on germinating in 4 inch pots, and I am trying to figure out two things

  1. when to begin germination, and

  2. how to take good care of them (enough light, heat, no frost, birds etc) until they are big enough to transplant outdoors 100% of the time in my 25 gallon pots.

Should I just go ahead and germinate now as we are 13 days into spring, and after they sprout keep them outdoors (provided no rain) and bring them inside at night? Is it that simple and I am overthinking?

Not sure how many weeks it takes them to be big enough to transplant to the final pots, 2? 3? 4? But depending on how long that is, it will either take me before or past the ‘last frost date’ here. If before and I have transplanted and we have a night of frost coming up, I can just put frost covers on them or something?

Or should I try and time this so that the plants will be transplanted after the last frost date. So let’s say last frost date is Nov 1 and growing them to 8 inches takes 2 weeks… I would germinate in the middle of October I guess?

Thanks anyone for tips, this is doing my head in! :slight_smile:


This can work. You’ll just need a light to be sure to keep it in veg when you bring it in.
@Oldguy and @kaptain3d how do you start yours?


Heres an idea get a heating mat (if possible a waterproof one) put it outside under the your seedling cups and use on chilly nights otherwise you could just leave them out during the day and bring them in every night


@Covertgrower. Thanks for the tag brother.
Personally I’d wait till the nite temps are going to be 10 c / 50 f or better Before putting any little ones outside.
Domes work well for the transition time till big enough to Leave out.
I start my seed at least 3-4 weeks before putting them out.
A 12 in plant going outside has a better chance of survival than a seedling at 3 in imho.
I use 5 gal water bottles with the bottoms cut off and when the plant reaches the neck I’ll remove the bottles.

A cfl or two will work for the first few weeks to get things started but after that it’s either a bigger light or outside they have to go.
Hope this helps you with your decision.


I like that 5 gallon jug idea!


Thanks all!

The tricky part is I can’t use artificial lighting at all (ridiculous, but that’s the law here), and that we only get temps above 10c at night in the last part of Spring.

Our weather schedule looks roughly like this:

September (Spring begins): min 4C, max 16C, daylight hours 12+
October: min 7C, max 20C, daylight hours 12+
November: min 10C, max 23C, daylight hours 12+
December (Summer begins): min 12C, max 26C, daylight hours 13+

This data is what makes me think no matter how I do seedling stage (artificial light or natural), I would have to start some time in early October for transplant time to end up being in November when min temps are at 10c at night. I won’t be able to move those 25 gallon pots indoors. lol.

I figure since we are getting 12+ hours of light in October as well it would hopefully be safe for me to germinate inside at the beginning of October, then keep them outside all day in October but bring them in at night (won’t be able to put under light though, it’ll be darkness for them at night)… and then transplant permanently outdoors in November. Curious if that is a solid plan considering my restrictions?

I like that 5gal water bottle idea for a dome… when you say “Domes work well for the transition time till big enough to Leave out.”, do you mean I could keep them domed like that outdoors during the day until they are big enough? I thought they were supposed to be uncovered after they sprout is why I ask.

Thanks government here for making this very stressful :sweat_smile:


@greenblood. Here we put out in mid May under the bottles and only remove daily for air exchange.
If you get a warmer day then lift off in morn and put back on at night.
Depends on the weather.
By the time the plants grow up into the neck of the bottle they’re pretty well established and the bottles can come off for good.
A bit like Like a mini greenhouse.


I don’t know if this is helpful, but I also had to germinate all of my plants indoors with no artificial lights. I have a window box with a deep window seat, and I germinated the plants there and kept the there for about two weeks. Then I started putting them outside in a sort of shaded spot everyday, and I brought them in at night. Now they are out in my greenhouse 24/7, where I put them when they were about 4 weeks. But they are in 3 gallon fabric pots

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@oldguy @grey20 @GreenSnek

Thank you for the help. Definitely given me some great tips that I can incorporate them into a successful plan now… thank you all! Appreciate you taking the time to respond. Here goes nothin’, eh? :slight_smile:

@oldguy one clarification, you leave the lids off the top of the 5 gal bottles? or completely sealed when they are on the plants.

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@greenblood. Most times the lids on for the first couple weeks.
Just make sure to lift the bottles daily to exchange the air inside.
After that then you can leave them off unless raining. :+1:
A buddy uses barrels cut in half for pots and puts a blue recycling bag over them to keep the excess rain from soaking his soil and beating his young plants up when they get to big for the bottles.
May help a bit in your situation too depending on your pot size.


You rule. That all sounds very useful and easy to achieve.Thank you once again, big help!

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Any time my friend. Easy is good. :grin:

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Sounds like New Zealand or Austrailia given the starting dates? The night temps are a small concern but not that big a deal, plant growth just stalls when its to cold. The humidity / rain could be a problem? Not sure about your micro climate? Ill assume moist coastal? Next is the dark hours… you should have at no more than 11 hours of darkness, anything more is flower time! That said, if you plant at 12 hours, the plants will not be sexually mature for at least a month more than likely, and that should get you safely into the 11 hour safety zone. Just keep in mind its the hours if total darkness not the amount of light that matters.