Effects of Unusual Weather

I'm relatively new to gardening. I'm in Maine, Zone 5a. We've had an unprecedentedly warm spring, with temps in the 70s and 80s all last week (never seen anything like it in my 50+ years). Thing is, everything seems to be waking up way too early. Last year I planted my first ever perennials and several are popping up -- Dead Nettle, Astilibe, Lilyturf and Day Lillies. I also planted a bare root rose bush last week after being told it was OK to do so as soon as the ground was workable. The weather people are predicting overnight temps in the low 20s, upper teens by mid-week, with possible heavy snow to follow, all pretty normal for this time of year. The question is, will the return to sub-freezing temps after such incredible warmth harm the plants that are popping up or the newly planted rose? Is there anything I could or should do beforehand? I'm feeling much anxiety.

Plants that are popping up on their own will be OK in the long run. You may lose blooms or fruit but not the plant.
I would throw a sheet over the rose on nights that get down to freezing to protect new growth that may be budding.

Everyone appears to be experiencing weather un-predictions this early on in the year, we have had storms, very wet ALL last year and damage everywhere by high winds yet, this week I am in the midst of the warmest spring to date and I have Rhododendrons, in flower 8 weeks too early (maybe due to all the rain we had during the summer months last year when these plants are making the flower buds for the following year) my delphiniums are about 6 inches up and you bet we will get night frost, my Rhubarb has gone walk about and rotted due to wet rotting roots, All spring bulbs have been in flower for weeks and my Blue Bell wood is about to show colour as the flower heads are on show but nature has a way of delaying things IF the change is not instant. I hope you are able to carry on and just enjoy what nature has done already, find ways to prolong the flowering season like dead heading, watering, feeding later on, and you may be able to make the garden last longer, hope so.
Good luck. WeeNel.

I thought Maine was zone 4a 4b.....but then I always thought here in Indiana....MUCH Warmer then Maine, I LOVED Maine...I was in zone 5 and where I am located in more 6. I don't really get it but we too have had a warm spell....no winter to speak of.

I am in 5a as well. roses, peonies, astilbes, dayliliies, bee balm, columbines and fritiliaries are all busting through the soil due to 2 weeks of ridiculously warm temperatures. I pulled back some, but not all of my winter mulch last week. Tonight I lightly piled some of the mulch back on the new growth on my perennials and placed light burlap over my rose and peony shoots. Keeping my fingers crossed. This is my first garden, and last year I spent so much time, blood, sweat, tears and money to get it going. I pray my heart will not be broken by the loss of any of my blooms. Good luck to all and if anyone has any other advice it would be welcome.

I do believe the new hardiness zone maps put Lewiston, ME in zone 5a. Probably considered more coastal.

http://letsgrowveggies.com/maine/04240/frost_dates/

You will be o.k. with things in the ground. We had the same thing here in N.Y. 6b. RELAX!

Thanks very much for everyone's input. Tommyr is right, I need to relax. We've continued with the odd weather -- almost no rain since the first of March until today when we 4" all at once. Very few nights have dipped below 32. Everything seems to be thriving except my hibiscus. I'll replace that soon. I won't worry so much the next time we experience a funky season.

Yes, Lewiston is Zone 5a. We're about 25 miles from the coast, so the ocean tends to moderate the temps just a bit. You don't have to more than 5 miles west of here to get into Zone 4 territory.

Thanks again everyone.