There are differant type of grass seed,sping wheat is shorter and stockier than winter wheat.May I ask what kind of seeds you are growing and where you got them from?I have grown hard red winter wheatfrom utah and texas.Same type but very differant in how the grass seeds grow.The texas wheat grows tall and skinny.Very uniform in hieght this indicates a uniform protein ratio of the seeds.The seeds I got frome utah which came from a mill was a blend of seeds with a non uniform growth patteren.A blend is not the best seed for maximizing the yeild per flat.I t is however the most inexpensive seed for growing grass.The texas seed came strait from the farmer through grower in texas.The seed is a bit more expensive but well worth the money in the long run.I purchased the seed at wheatgrassman.com a website worth checking out.And as far as putting your trays outside for sun exposier goes.Make sure they dont get direct sunlight it will stunt there growth.When I grow outside I use a 4tier growrack with a 60% shadecover.It protects the grass from the sun and critters as well.If you want to grow a thick bladed grass brley grass is the grass of choice for thick lusious blades.Once you get the basics down growing wheatgrass is very easy.It does take a little time to get your growing tech. down.May you be blessed with vibrant health,and happy growing!