Cast Iron and A Mid April Freeze

I love cast iron.  ...my cast iron wood burning stove.
...my cast iron pans (I have Griswold, Wagner's, Lodge, and some just good 'ole plain cast iron).
...my cast iron outdoor plant hangers.
...my new cast iron trivets...

...aren't they lovely?  These are small trivets, about 3x4, but will help distribute the heat to the cast iron pans when I cook on the cast iron wood burning stove.  I decided on two small ones rather than one larger, my thought process being that for my big mama pan that is about 15 inches in diameter, having two smaller trivets on each side of the pan rather than one in the middle will help distribute the heat more effectively.  Any of you engineers out there who would like to offer counter points please feel free:)

I've never been much of a collector of anything, but being here in our log cabin makes me love cast iron all the more...it is so easy to cook with, especially when using fire to heat, it is easy to clean, and it distributes and retains heat in the most marvelous fashion.  My next search is for a dutch oven with a lid and legs, the legs working the same way a trivet does...the search continues!

Speaking of retaining heat, we got hit with a freeze last night, and several of our plants are hurting today.  I totally respect nature and understand that there are things I cannot control; sometimes things happen with the weather that are not preferred.  Granted, no human harm came from this occurrence of nature, and I am completely grateful for this, but I am saddened nonetheless by the impact.  Our hydrangea (I was just admiring their budding bloom sprouts yesterday), blueberry bushes (full of flowers), hibiscus, and chestnut trees all look like their ability to protect themselves against the freezing elements was poor.  Their leaves are wilting and/or shriveling.  While we did find a sheet to protect our new raspberry bushes, we had to leave the rest to their own defenses, and it just wasn't enough.  I am happy to share that so far, our apple trees and gooseberry & raspberry bushes look like they made it through OK.       

I am wondering if anyone has any suggestions as to what to do to renew the possibility of spring blooms from frozen but not killed plants?  I appreciate any input you may have.