I am by no means an expert, but here is what I've learned reading posts here over the last month or so.

"5. Cut my grass short in Spring to encourage new growth of grass seed. "

Crabgrass germinates in the springtime. It likes to have sun and moisture. If you cut your grass short in the spring it will encourage the crabgrass.

What grass seed are you trying to encourage to grow? Are you putting new seed down in the spring? Are you allowing your grass to go unmowed long enough for it to go to seed? If you are not doing either of these things the weed seeds are the only seeds that are there to germinate.

If I am wrong I am sure one of the real experts will come along and correct me.

I think you might have a point about cutting it too short in the Spring even though I want my new grass to establish.
Another thing is there is so much rain in the spring I am afraid of getting behind in cutting it and letting it get to long to cut at times, like when it rains 5 days in a row!
I have seeded Pennington seed in the spring but find it does better when seeded in the fall.
I believe I heard someone else say to seed it like now (Aug. or Sept) is better for preventing crabgrass as well.

Also, we had a LOT of rain this spring in April so that probably made it thrive.

Yeah. Right now is the best time to seed. Seeding in the spring will give you a bumper crop of crabgrass ;-) If you seed now it will be strong enough to survive the winter and long enough in the spring to shade the crabgrass.

watering mowing and fertilizer are all important in keeping your lawn full so there will be less weed pressure.

dchall_san_antonio has "the basics of lawn care" posted a lot on this forum. The link at the bottom is a random thread that he has posted it in.

Here is a link that might be useful: dchall gives