You must have planted a dwarf variety.

Pictures I've seen of commercial fields of black oil sunflowers show plants 5-7 ft. tall. There could easily be dwarf kinds, since that would tend to simplify harvesting, so check the specs for the variety you bought.

Otherwise, check the watering, feeding, soil conditions, and planting date. Oil seed sunflowers are more drought tolerant than those grown for flowers, but lack of water will tend to stunt it. Lack of nitrogen will also tend to stunt them--feeding with "bloom-booster" is often counterproductive. Poor, sandy-gravelly soil makes both water and nutrient retention questionable. On the other hand, poor drainage from hardpan or heavy clay soil stunts roots, and inhibits nutrient absorption. Although sunflowers are fairly tolerant of differen soil pH values, extreme alkalinity or acidity can do the same. Most sunflowers need a minimum of 80 days from planting to extreme heat or near-freezing to develop fully. If conditions become too unfriendly, they will grow a few stunted flowers on a short plant, just to reproduce before they die.

Good luck!
Kevin : )

thanks y'all

Kevin : On the other hand, poor drainage from hardpan or heavy clay soil stunts roots, and inhibits nutrient absorption.

I believe that was my problem. the soil iplanted them in was very clayish and hard. thanks

can sunflowers crossbreed? i want to grow black oil and mammoth sunflowers.

I know that they crossbreed, but I'm not sure what effect that will have on the seeds. Your Mammoth seeds may come out tasting funny! The next generation would probably show even more variation in seed size and quality. I'd plant them far, far away from each other.

Kevin : )

wow! kevin i want to plant them FAR, FAR away!

Texas is home - where did you get your seeds? I bought some bird seed and tried germinating them and they took so I thought I would just use them. Now, reading yours only grew to 2' I may reconsider if you took the same route. Thanks.

Oh they'll grow alright! We bought some old bird seed on clearance (my guess is they were very old... Which could hinder germination) and i didn't know much about BOSS at the time so i even stratified them! >.