Are there female krogan

there are they just never leave the homeworld the constantly are breeding trying to produce more krogans as a result of the geno thingy

Actually, nothing of the sort is ever stated anywhere in the Mass Effect universe. There most definitely are female krogan, and it's been demonstrated that, even after the genophage (aka the "geno thingy") they do leave their homeworld of Tuchanka (take, for example, the Warlord Shiagur, and krogan females who appear in Fornax, to say nothing of krogan females on other krogan worlds). We've even seen a krogan female now, as there is one in Mass Effect 2. Sure, she's dead, but she's still there. We just haven't yet seen one walking around and talking and whatnot. Also, just throwing this out there... the plural of krogan is krogan, not 'krogans'.