Join Date: Jul 2010
Location: East Central Illinois
I've lived on my 5 acres (4 acres of gated grazing/riding areas) for about 12 years now. If you want a no-worry solution don't put your horse out to pasture until June, and if you're getting a monsoon then, wait a little bit longer. Otherwise, about one hour of grazing, even on fast growing spring grass won't hurt your horse.
It's all about a high concentration of carbohydrates that occurs in fast growing spring grass, and it is higher in the afternoon than in the morning. Put a halter on her so you can yank her off of it. She'll be eating like there's no tomorrow. My Vet comes out every spring to give shots and I get the lowdown on this year's grass founder cases. She gives shots for this, too, to prevent founder. Another thought, if you can train her to it, is to use the US Cavalry solution, a picket pin. We have 4 of these, and they pound into the ground with about 25 ft. of rope and a snap for the halter. Your horse can only graze the circle around the pin, so you have more control. HOWEVER, they can get a nasty rope burn if they aren't used to it.
Talk to your Vet about this, too.