Columbines produce about 75
seeds per seedpod and there is a seedpod for each
flower produced. So if you can do the fall or winter sow you should have plenty from very modest starts. Also the columbine mutates easily so each year you'll have different color combinations to sell.
Miniature Snapdragons produce about 25
seeds per seedpod but I found them more difficult to harvest but then I'm sure some of that was my inexperience and impatience. I picked many before they were dry. These bloom both
spring and fall so you should have a bountful havest.
sunflowers produce a massive amount of
seeds as long as you are willing to net the
plants so the birds don't get to the
seeds first.
Zinnias also produce a boat load of
seeds per
flower head. Again my problem with these is that I got alittle impatient to harvest them and started to soon. This decreased the number of
seeds that germinated dramatically.
Miniature
roses produce about 25
seeds per
rose hip but I haven't tried
growing them yet. It's suppose to take close to 4 months or more for them to sprout so this might not be worth it.
Malva are also said to have generous
seed production and I was able to start mine indoors and they did very well.