extreme spring -- ending?

Submitted by externmed on

OK, we've had several weeks without frost and plant growth is advanced to April 20-30. Now it's going to be down to 25F. Any ideas which plants need to be protected more and which less. I know the magnolia flowers are going to be toast, but I'm not so sure how various bulbs and perennials are going to do. Any thoughts?
Charles Swanson
NE Massachusetts USA 6A (7 this year)


Submitted by Mark McD on Sun, 03/25/2012 - 17:52

Charles, we're both wondering the same thing.  In the past several years we've had a number of exceptionally early spring seasons (although none as early as this one), and in particular I remember one such similar case, where after a prolonged mild spell we got whacked with an 18 F deep freeze one night.  That spring I lamented my early cleanup on a mature dwarf Iris gracilipes 'Buko' with all of the protective "thatch" around the growth points removed.  It slowly but steadfastly died after that exposure.  The smaller plants that were not "de-thatched" were fine, so this year I'm resisting the urge to clean up too early.

I have Tulipa & Fritilaria species in bud (complete with early arrival of lily beetle ;) ), but I think these will all be fine.  Some shoots on things that emerged much too early, may be frozen back, but ultimately I do think most things will be okay, or will recover from any damage.  Of the 200 or so Epimedium varieties I grow, maybe about 2 dozen are in a state of advanced emergence right now, and I worry that the tender young growth (full of buds) will suffer, we shall see.  My Townsendia rockrothii is in pseudo-flower right now, with odd semi-developed flowers from the season being rushed, a deep freeze may toast the flowers but I think the plant will be alright.

Yes, the Magnolias will all be hit, with browned buds.  My M. 'Forrest Pink' is full of closed flowers, even though closed, the rich perfume still able to perfume the area where it is growing.  I recall too, one year where we had a deep sudden freeze later in the season, where all of the Magnolia 'Forrest Pink' leaves were completely blackened, hanging there like limp rags, but it re-leafed out and came back okay.

Last year I was trialing some of the Agastache hybrids from David Salmon of High Country Gardens.  They're being grown in pots outdoors (until I find just the right place to plant them), and were overwintered by mounding mulch around the potted plants, but otherwise totally exposed.  I'm pleased to say, they look terrific, with good fresh growth on all.  Tomorrow night after work, I might pile some leaves over them just in case. 

Let's compare notes next week :)

Submitted by externmed on Wed, 03/28/2012 - 08:02

Amazingly all the perennials seem to have survived 23 - 25F with no damage.
After cooking at 80F. I guess on a calm night, ground temps may be 10 or more degrees lower, causing serious damage.
Wishing everyone else good luck, too.
Charles Swanson Boxford MA USA