I'm wondering if I can use certain seeds from the food department rather than from a garden center, as you get so much more for the same price.

I have pumpkin seeds, hulled sunflower seeds, canned corn without salt, popcorn.

Should I soak all or some of them?

I'm mostly interested in the ornamental aspect of these large plants for my garden.

Thanks!

Really doubt that you could get the canned corn to grow... The rest? Go ahead and plant.
You shouldn't need to pre-soak.

Edit:
Hmmm... hulled sunflower seeds... Roasted?
raw? salted? Roasted or salted... unlikely to work... might want to try the ones from the bird food.

They always die from drought, but most of the beans from "15 bean soup" can sprout.

Anything canned, no.
Anything roasted or cooked at some point, no

A lot of seed in packets is good for more than a year or two.

You need mature but uncooked whole seed.

Popcorn I think will grow as it wouldn't be heat treated or it won't pop, right?

Birdseed can be millet, that's a corn like plant with a spray of seeds at top. Whole corn from birdseed, sunflowers of course. Safflower will grow but wasn't very pretty to me.
Papaya- I had a bunch of them volunteer last year from compost. They are fast growing and tropical looking, sort of like a green Castor bean plant.

You won't necessarily get what you think you are getting. A lot of foods are first generation, unstable, hybrids. They'll have a tendency to revert back to one of the parent varieties that were crossbred to produce the seeds that grew the food you purchased. You might also get first generation crosses from stable varieties that were planted in pollinator distance of another variety.

It's also not uncommon for produce to have been picked before the seeds have fully matured. You might get little or no germination if you try to grow those seeds.

THis is a fun book I had I think was written in the 70s.
https://www.amazon.com/dp/0898154502/

But if you want sometihng fast, ornamental and only growing for the summer, you're limited.
If you want something you will take in for winter- citrus are easy to grow from seeds

PattyPan said: You won't necessarily get what you think you are getting. A lot of foods are first generation, unstable, hybrids.

I think this warning is over emphasized... Maybe a belief that the seed hybridizers are financially motivated to promote?

I've planted a lot of those grocery produce seeds often without noticeable differences.

Of course, sometimes there are differences, Especially the time I grew strawberries from grocery store produce... Looked the same... but bland... yech...
I grew musk melons with slight variability... They all tasted fine.
When I grow peppers... very similar to original fruit.

Surprisingly, picking produce green may not limit seed viability...
I've seen a lot of seeds go ahead and ripen in those immature fruits.

I've also uprooted plants with unopened flower buds... And seen them flower and set viable seed while lying on top of the soil!

Life finds a way...

"I'm mostly interested in the ornamental aspect of these large plants for my garden."

I'm still trying to think of large interesting plants you can grow from something in the 'food aisle' or non-seed packet source. Hybridization, I think won't matter much in the look of the plant.

You mentioned pumpkin seeds and hulled sunflower- sounds like those are processed for snacking, so probably no. But any whole hard winter squash should have hundreds of mature seeds, probably will grow a rambling vining plant with big leaves. Ditto fresh watermelon with seeds.

As mentioned, birdseed should grow. But depending on your choice of shopping, if you have to buy a bag of pounds of seed just to grow a spoonful- you may as well go get packets. Unless you want to feed the rest to birds.

I haven't gotten mango to grow but I cut the pod open once and the seed inside already had a root sprouted, curled up.

Other foods, not seeds, in the produce aisle can be a cheap way to grow - I have grown elephant ear type plants, sold as yautia and edo, they are edible roots.

sallyg said: I haven't gotten mango to grow but I cut the pod open once and the seed inside already had a root sprouted, curled up.

Yeah... me too...
As good as they are... with that huge seed... seems like it should be easy...

Try papaya... small seeds, come up easily (as sallyg mentioned above), looks like an okra plant.
Unfortunately... the fruit needs to ripen on the plant, and it usually frosts here at about the time the fruit only needs a couple more weeks....

Papaya grows into this huge monstrous plant... very interesting...

I tried potting one of the papayas that grew in the garden, it didn't grow. But starting it in a pot in fall or winter, THEN putting it out for summer- just maybe you can get a fruit? And any other tropical fresh fruit with obvious seeds.

I am interpreting the original question as 'What can I grow cheap, commonly found in the store, big interesting looking plant."

As mentioned, a lot of whole dry beans may grow, likely a vine with flowers. You can test them in a wet paper towel for a few days, look for a root to emerge.