Planting tall fescue?
I have a some what established new lawn, it's just thin. Being thin is allowing weeds of all verieties to pop up. I would like to aerate and sow the seeds in now to try and thicken the lawn. From what I've read spring is not the best time to plant fescue. Is this true or should I go for it?
No, do not aerate now this opens up the soil for weed seeds so do this again in the fall. You should fertilize, mow at a proper height (about 3-4 inches), in the hottest part of the summer mow only when needed, and irrigate if possible (again only when needed). See page 9 of the following publication for more information, http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG102%20La...
If you think crabgrass may be a problem then apply a preemergent. It is a little late so use Dimension (Dithiopyr). But read the label before applying to see what it says about applying to a newly seeded lawn.