Because frost damaged Japanese maples and so many other trees
in spring 2012...
Many important trees all over the Eastern U.S. and Canada were
damaged in the precocious spring and unfortunate frosts of 2012.
The toll included many thousands of Japanese maples. We dedicated
much of What's Coming Up 179 and all of What's Coming
Up 181 to the situation.
Here are updates as they occur.
March 21: Many trees and shrubs leaf out 3-5 weeks ahead of
March 25: A frost brings to an end one of the earliest and
longest saucer magnolia bloom periods the Great Lakes region has
ever seen. Blossoms are killed. Some foliage is damaged but most is
spared, having been still tight in bud. To the untutored eye, it's
a matter for great concern since the trees look so brown from all
the clinging dead petals.
April 21 - 28: A series of normal frosts catches many trees,
shrubs and perennials in full leaf. The earliest frosts are
overlooked by many. A freeze on April 28-29 is more noticeable, as
it kills all or much of the foliage on many Japanese maples (and
other trees and shrubs, list below).
April 29 - May 3: Questions flood all horticultural centers. The
answer is consistent among the experts: Wait for new growth to
develop and assess the toll at that time. However, many people are
not tuned in: Many Japanese maples and other well established trees
are being cut down or removed as "dead."
May 3: What's
Coming Up 179 reports the situation, advises patience and
provides the detail, "You will see new growth in 3 to 4 weeks.
May 20: What's Coming
Up 181 reports new growth, recommends watering, provides
data indicating near-complete recovery entirely possible, and
cautions against premature pruning.
What's Coming Up 182 reports additional new growth is
still appearing on bare wood, advises hold off on pruning.
To cut boldly: Upcoming subjects reports that some of
these trees made such poor recovery that they should not be pruned
this summer even if the schedule says this is their year to be
pruned to stay small.
Other trees and shrubs that were damaged.
Japanese maples command so much attention that most people took
quick notice of their frost damage. Other trees were out of sight
overhead, nipped earlier in leaf development, or otherwise escaped
attention. Any of these plants may develop weakness or branch
dieback later in the year, which may have its basis in the frost
blue mist spirea/bluebeard (Caryopteris)
butterfly bush, (Buddleia)
honeylocust (Gleditsia triacanthos)
katsura (Cercidiphyllum species)
mulberry (yellowwood (Cladrastis lutea)
oaks (flowers killed)
sycamore and plane tree (Platanus species)
yew (Taxus species)
Unusual perennial losses
Many perennial plants were damaged by March and April frosts.
Some of those most mourned, most unusual, or which may have been
damaged in ways that a gardener may not associate with frost:
Hosta. Crowns as well as leaves may be damaged. Summer
dieback and blight of damaged tissues may be in store.
Old fashioned bleeding heart (Dicentra spectabilis).
Foliage killed, flowering stems killed.
Bergenia, English ivy and Ajuga: Crowns
damaged, foliage emerging with deformities. Crowns may continue to
deteriorate and die back during summer heat or next winter.