Some of my plants look terrible after the mild frost 5 days ago. I had 31 F in my garden but unfortunately also frost. Now leaves are turning yellow-brown and of course full of spots. Thankfully temperatures now are much higher, around 60 F.

I am wondering if there is some trick, something I can do to help them survive, boost their chances a bit? 

I don’t know of any tricks , other than thermal protection and hoping for warmer weather. Once the fronds are damaged they have to grow out of it and that will occur as we get closer to Spring, hang in there. Harry

Sounds like you have done pre winter protection, it’s up to Mother Nature now, welcome to the zone push club where you get to watch palms die and you also get to watch new palms live. See socratea rostrata picture below for a zone push winner! 

29 minutes ago, happypalms said:

Sounds like you have done pre winter protection, it’s up to Mother Nature now, welcome to the zone push club where you get to watch palms die and you also get to watch new palms live. See socratea rostrata picture below for a zone push winner! 

A beautiful species! It comes from Colombian Andes, so I guess it doesn't like cold but doesn't like heat either.

5 minutes ago, Than said:

A beautiful species! It comes from Colombian Andes, so I guess it doesn't like cold but doesn't like heat either.

Everyone’s a winner! 

Not all is lost, you will discover that palm trees that were supposed to succumb to the frost have actually proven to be more resistant.

1 hour ago, gyuseppe said:

Not all is lost, you will discover that palm trees that were supposed to succumb to the frost have actually proven to be more resistant.

Actually I have already seen that palms that were under cover seem so much stronger than those who were not. Impressive. Even though the temperature was identical for both. 

20 minutes ago, Than said:

Actually I have already seen that palms that were under cover seem so much stronger than those who were not. Impressive. Even though the temperature was identical for both. 

good, great news

you will have to put up with some ugliness for a while.  Trim off the brown when it turns and let the plant do the rest.  I have a beccariophoenix alfredii that was ~90%  frost burned as a small 80 cm tall size palm at 28F.  I thought it a goner as very little green was left and all the newest leaves were toast.  Today its a monster with 30'+ height.  Frost burn often doesnt kill unless the bud freezes.  Cold tolerance is death not damage to foliage.  Do not over water or fertilize yet.  Wait till it gets warmer and add some fish emulsion.  

1 hour ago, sonoranfans said:

you will have to put up with some ugliness for a while.  Trim off the brown when it turns and let the plant do the rest.  I have a beccariophoenix alfredii that was ~90%  frost burned as a small 80 cm tall size palm at 28F.  I thought it a goner as very little green was left and all the newest leaves were toast.  Today its a monster with 30'+ height.  Frost burn often doesnt kill unless the bud freezes.  Cold tolerance is death not damage to foliage.  Do not over water or fertilize yet.  Wait till it gets warmer and add some fish emulsion.  

I am also optimistic for most; I was just wondering if anything can make them heal faster. I guess I just need to wait.

Wait until May. You can also spray the most tender palms with a copper fungicide. If meristem is also affected, it would prevent a fungal or bacterial outbreak. But this works better in case of snow cover.

8 minutes ago, Phoenikakias said:

Wait until May. You can also spray the most tender palms with a copper fungicide. If meristem is also affected, it would prevent a fungal or bacterial outbreak. But this works better in case of snow cover.

Thank you. I sprayed with Bordeaux mix about 2 weeks ago and I will repeat monthly.