Controlling Tall, Thick Grass Patches in a Newly Seeded Area

After removing shrubs and seeding grass, a homeowner finds patches of very thick grass growing a foot tall while the desired grass is only 3 inches. The expert offers three options:

1. Apply a plant growth regulator after mowing to suppress regrowth. Precision is crucial because overdosing can kill the grass.
2. Treat the unwanted grass with Roundup and re-sod the area.
3. If the desired grass spreads by runners, scalp the unwanted patches repeatedly so the desired grass runners can smother the invader.

The choice depends on the grass type and the homeowner's preference for chemical vs. cultural control. Option 1 requires careful calibration; option 2 is more definitive but involves re-sodding; option 3 works only for spreading grass types.