Lawns - Proper application of fertilizer in 'transition zone'?

I live in central Virginia and have tall fescue. My lawn is in decent shape, but it's not as dark green as I'd like. It's more like a dull light green (but not yellow). I have in the past followed the fertilization schedule that is recommended by the Virginia co-operative extension. That being fertilize 2 - 3 times in the fall, and a small amount in the early spring (or none at all). So, my grass looks great in the fall and early spring.

Is it best for me to follow this advice, or is it okay to fertilize in the late spring, and/or summertime? I am thinking of following the Scotts program of fertilizing, and am wondering if putting down fertilizer in the summer heat will harm my lawn. They call for putting down Scotts Summerguard around this time of year.

:confused:

I do have an irrigation system.

Thanks.

I forgot to ask - is putting down Ironite (or similar product) an alternative for greening up my grass in the summer? I've never used this type of product before.