Practice with things which are already primed for an autumn sowing - not sunflowers. Go and buy some cheap hardy annuals now - might I suggest cornflowers (centaurea cyaneus) and simply sow them outside in a pot. They will germinate in a week or so (it doesn't matter which way up you put the seeds - plants have an awareness of gravity (geotropism). Or conversely, buy a few perennial seeds which will benefot from a winter startifying in the cold and wet. You won't need supplemental lighting, just the odd bit of water if the pots dry out and they can stay out all winter - just cover the pots so they are not covered in deep snow...and in May, you will have cornflowers as big as a shrub. Jumping in at the deep end, with unneccessary technicalities, will be more of a dampener than encouragement. Just my twopenn'orth.

By the way, most seedlings will not need extra nutrition for a few weeks as nearly all potting mixes contain some base fertiliser.

Thank you for your reply! You are absolutely right and it was my first instinct to get more appropriate seeds after doing some googling. However, I live quite out of the way, with 1 big shop within a 30 mile radius (and I don't even drive!) and they told me they had just stopped stocking seeds of any sort in preparation for winter. I even tried harvesting seeds from local plants, with little success so the snack sunflower seeds were really the last resort. Like I said, I set out fully expecting a failure and I still am, since these are sunflowers facing Winter. I just learn best from making mistakes, so I'm going to see how long I can keep them thriving and hopefully learn something new.

Here is a progress update. The one I thought dead ended up sprouting from the soil! I think they're looking ok, and they might grow without problem for a little while more.

(the 'middle' child)

(the younger one that surprised me)

Hi otmeek. Your seedlings look fine to me! If I cannot give seedlings enough natural light, I use fluorescent lighting (4' banks) set to 15 hours a day. I understand that you're just experimenting and don't have easy access to seeds... try saving seeds from your produce to play with! Ripe (usually red) peppers and tomatoes will certainly both work -- as long as you understand that the produce was most likely a hybrid that wasn't pollinated under controlled conditions. Meaning, you may not get the same pepper or tomato from their saved seed. For example, I bought really good mixed-color mini sweet peppers last winter, so I saved the seed as an experiment. I'm growing fantastic mini sweet peppers this year from that seed I saved in winter! What I grew ended up being exactly like the mini sweets I had purchased, and I'm growing all three colors (red, yellow, and orange). Seeds from mature winter squashes and pumpkins can also be saved... again, there's no guarantee that you'll grow the same squash/pumpkin from those saved seeds, but you will grow *something*. Essentially 'free' seeds. :)

@party_music50 thank you for your reply! I might try tomatoes some time. I actually got my hands on some hardy bulbs so I have a winter project with better prospects but I'm still keeping track of the sunflowers. They're doing quite well I think, although they are recovering from what I think was over watering.

This one grows its true leaves in sets of 3, not 2 for some reason. I wonder how common that is!

Cheap seed for practicing could even come from your dry goods....dried beans, peas, lentils, pop corn etc....or your spice rack. Hot pepper flakes have seeds in them, cilantro, anise seed, mustard seed, celery seed etc.

I used to do this when I was a kid trying to teach myself to be a farmer. I now do it with my children....beans and pop corn are my favorites to do with children. You will have to eventually toss the corn, but the beans you can keep going as a house plant/continuing experiment in my experience.