HELP! Spindly young seedlings

[Islander]

I am a new grower, growing a CBD strain for medical use. I planted my 5 seeds 2 - 3 weeks ago in 3" jiffy pots and the seedlings are now about 4 - 4 1/2" high. The first leaves(2) are about 3 " from the soil surface and next node is about 4". This growing mixture has a limited amount of actual soil. These were started inside in a living room window with lots of light. These grow towards the light and I am turning them 2 to 3 times per day. My plan is to eventually have them outside. My concern at this point is that the stems seem somewhat spindly/leggy. Reading online some are suggesting to repot in a slightly larger pot ... and transplant deeper to raise the soil level on the stem. I live on the east coast of Canada, and outside temperatures are still cool. Also any suggestions for soil mixture for transplanting ?

[Gingerbeard]

How old are your windows?

[Islander]

30 years at least

[Gingerbeard]

Your house is new enough that you might have E-rated windows. Basically, windows that don't let all the good light through.
Used to be windows were made from a single layer of hand blown or float glass with no treatment. These days there are 2 or more layers of glass that have been treated to keep out hot and cold, and UV rays and junk. They also have an inert gas injected between the panes before getting sealed up. While the E-rated windows are great for letting in a lot of warm light, they don't let in enough of the right kind for sun loving weeds.

[Gingerbeard]

It is also a real good idea to post a picture of where and what you have going on.

[bboyfromwayback]

Seedlings do best under T5’s until they get their roots. They like the heat and the spectrum keeps them short instead of lanky

[Gingerbeard]

I started under t-5's. Good memories. I'm shedding a tear. Closet swirl was the generic name for any of the seeds an old, old-head buddy cross bred in his closet for a zillion years. One male out of many dozens planted.
But, yeah. t-5's are great.

[Rwise]

Stretching means they do not have enuf light, and it will not make any dif to start them in some weird pyramid media. Plant them in a larger pot up to the baby leaves and give them more light. (not to much you can burn them)
Windows can let enuf light to sprout under, but if you want UV it will take special glass for it to pass through.
There are many LEDs that are not expensive and do a reasonable job for the cost, even CFLs will do a better job than your window. Coupled with a timer and follow the sun schedule if your going outside with them. Remember to harden them off before planting them in direct sun light.

[Bornintheusa]

Stretching means they do not have enuf light, and it will not make any dif to start them in some weird pyramid media. Plant them in a larger pot up to the baby leaves and give them more light. (not to much you can burn them)
Windows can let enuf light to sprout under, but if you want UV it will take special glass for it to pass through.
There are many LEDs that are not expensive and do a reasonable job for the cost, even CFLs will do a better job than your window. Coupled with a timer and follow the sun schedule if your going outside with them. Remember to harden them off before planting them in direct sun light.

Hi.
I’m growing a few auto seedlings that I feel the time is right to move outdoors. Can you explain what it means to harden them off?

[Rwise]

If you put plants straight out in direct sun, it will burn them. So put them in a place they get some sunshine for a few days then move them to more sunshine. This "hardens" the plant so it can take full on sunshine.