Gordons Ornamec 170 Grass Herbicide is not labeled to safely be applied to milkweed and will likely cause harm to it therefore we woud not advise applying in or around milkweed.
For recommendations, we recommend contacting the Master Gardener Division with your County Extension Office for suggestions on a selective herbicide safe for Milkweed.
Per the manufacturer, you should wait 2-3 weeks to seed in the area after using Gordons Ornamec 170 Grass Herbicide.
If you do plan to schedule an aeration for your lawn it is important that any pre-emergent herbicide be applied after the aeration is completed. Aeration can be done spring-summer excess moisture is known to sit on the grass.
