Can these lavender plugs bounce back after I overwatered them?

Lavender is much better suited to life outdoors than on a windowsill. If the weather is suitable, start moving the plugs outside gradually so they can adjust to the stronger sun, then give them a sunny spot with good drainage.

First, make sure excess water can drain away and the pots aren’t sitting in water. Don’t keep adding water while the mix is still wet, but don’t leave tiny plugs bone-dry for ages either. Once they’re planted and settling in, water when they need it rather than on a fixed daily schedule.

Try not to judge the whole plant by a few dull or crispy flower heads. Lavender flowers naturally fade, and that alone doesn’t mean the plug is dying. Look at the foliage and stems too. If only the spent flower stalks are dry, you can trim those without cutting into the bushy woody base.