Re: Overwintering Cannas and Hedychium

Of the 'gingers' I find the most successful by far are the Hedychiums,
but even then I have to be a bit selective, since some need a very
long season of hot weather to build up to flowering.  All are
thoroughly winter hardy here without needing any protection, but a
thick autumnal mulch of seaweed goes a long way to preventing the soil
from getting so cold as to enforce total dormancy.  If this happens,
the plants take a long time to wake up and can miss flowering for that
year.  The worst culprit in this respect is the relatively common
Hedychium coronarium.  This species needs a couple of years to build
up enough reserves to enable late summer flowering in our climate and
is wholly unsuitable for permanent outdoors growing away from the
south coast.  Oddly, many of its hybrids and varieties are less
reluctant.

The only species that I can hand-on-heart recommend to Tim is H.
densiflorum.  It is very hardy, tolerating a fair amount of freezing
to the roots and happily, requires a relatively short growing season
in order to flower.  Here it commences in late June continuing to
November, in the Midlands it flowers by early September and I suspect
that up in Tim's neck of the woods, it would start around mid or late
September.  It is the first to enter total dormancy and the first to
wake up.  

The flowers are not quite as spectacular as many of the others but
have a quiet charm nevertheless.  I've raised a few questionable
'hybrids using this species as well as some rather fine 'selfed'
seedlings.  The best is a variety I have nick-named 'Buttermilk' since
the spikes are a warm, creamy yellow.  The commonest colour seen in
this species is a rather pleasing orange scarlet.  I have a very large
clump which is stifling some Alocasias, so I dare say that Tim will
happily accept the inevitable 'cut-backs' which will have to be made
along with the seedling Cordyline indivisa which I keep meaning to
send!

Alpinias in general do not do terribly well since our summers are
neither hot nor long enough for them to perform well.  I use Alpinia
japonica as ground cover, but it is a martyr to slugs, snails and
caterpillars.  Occasionally it will send up a squinny spike of
purplish-pink flowers, but you have to look long and hard to persuade
yourself they are that attractive.  

I also have the pin-striped Alpinia formosa, but a slight set-back
takes a couple of seasons for it to recover.  I got it to 3 feet high
last summer, but last winter's rains and occasional, ensuing frosts
saw off the stems, leaving just a few basal leaves.  It has made more
basal leaves this year, but will take another couple of summers to get
back to normal.  Not a very satisfactory plant.  

Alpinia zerumbet is possibly one of the more spectacular species, with
stout canes towering skyward and very glamorous, orchid-like blooms at
their tips.  No chance of seeing them outside a greenhouse anywhere in
the UK - it cannot cope with our long cool winters and even without
frosts, invariably dies back.  This species seems to need a good 6
months with temperatures well above 60F and a very few weeks with
temperatures dipping below 40F.  It can recover stupendously in
regions which have spring heat surges, but not in the UK.  That said,
I reckon that the exceptionally handsome variegated form - A. zerumbet
'Variegata' is worth trying (with winter protection) for its leaves
alone.  

Dave Poole
TORQUAY  UK
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