Q.Do I Need To Cover Hyacinths That Started Blooming While It’s Still Freezing Overnight?
I’m in zone 8b at 4500′ in the foothills of a northern mountain slope. The past two Februarys, I used plastic milk jugs to cover my blooming hyacinths when freezing was predicted overnight. A friend who lives at a higher elevation and gets more snow than I do said she doesn’t cover hers and they are ok. I have 32 bulbs in the ground and it’s quite a pain to cover and uncover every day, but I’ll continue to do it if necessary. Your advice? Thanks. Sharon Brown

Certified GKH Gardening Expert
You have nothing to worry about. You are well within their cold tolerance (You are in zone 8/9), as they can withstand the temperatures of zone 3! Actually, they need that cold to complete their lifecycle.
https://www.gardeningknowhow.com/ornamental/bulbs/hyacinth/planting-and-care-of-hyacinths.htm