Greetings Kate!
I'm not sure if it would work, I think it might be too darn hot in June. Seems like they fizzle in the summer. Maybe try it with half or one third, then underplant with sweet alyssum(the purple ones) as a filler? Or take them out now and put the moss rose in so it will be lush in time for the garden walk. I think pansies will only grow in the cool weather.
-B

I am no expert, & I am in zone 7, so maybe not exactly the same situation, but I have pansies which I planted last spring. I kept them watered through the summer heat, and they have never stopped blooming. All summer, all fall, through winter, now they are flourishing. Good luck, and happy gardening!

The key factor will be just how hot it gets between now and June 14th - something that you cannot control. Hot weather slows down the recovery time also so I would cut them back but not too much (cut a third of each stem away) and feed them every week.

Every year they come out with more heat tolerant pansies and violas - in the same old colors so you wouldn't always notice the difference. So maybe your current crop is one of the better varieties and will stay in good shape for you. You should be able to see the buds forming a week or so in advance. If you don't see buds and the leaves are starting to turn yellow, run out and buy the moss roses.

I have seen pansies and violas do amazing things. They don't always follow the rules!

Good luck.

Thank you for your advice, everybody. I decided to try to keep the pansies that get some shade (following your recommendations), but replaced the pansies that were in full sun all day.

Wouldn't you know it--weather has been rainy and cooler for the past week. But may head up to 90 in a couple more days, so .... we'll see. LOL

Kate