January 2020 - 38

CULTURE REPORT
Begonia
T
This new series of tuberous begonias brings a new option for
shade annuals and offers a leap forward in breeding.
BY BART HAYES
he genus begonia is one
of the most diverse in
the plant kingdom and
continues to provide our industry
with a diverse assortment of
varieties to meet the demands
of increasingly well-informed
and savvy plant consumers.
Whether in sun or shade, fibrous
rooted or rhizomatous, potted
or bedding, begonias provide
an easy-to-grow option for the
plant novice, the loft-dwelling
urbanite, or seasoned gardeners
alike. For breeders, it is a deep
pool of genetic possibilities. A
challenging plant to work with
but rewarding if good crosses are
made and selected.
BACKGROUND
Tuberous begonias, specifically,
have become a staple of our
industry for their massive flowers
and flexibility on sun/shade
requirements. But, as the name
implies, these begonias will
form an underground storage
organ under short daylengths
or stressful conditions. And,
although breeding has made
growing this class of begonia
easier to produce and grow, some
advancements, specifically flower
size and quantity, have created
other production issues.
With large, abundant flowers,
you create a food source for
Botrytis once the old blooms
drop, especially the first few
flowers, which tend to be covered
by rapidly growing foliage. This
low air movement environment,
combined with the spent flowers,
and moisture from regular
watering can lead to serious
38 JANUARY 2020 GPNMAG.COM
Botrytis outbreaks, which can
cause losses or require additional
chemical applications to control.
The Prism series of tuberous
begonias from Westhoff not
only brings a new option for
shade annuals but offers a leap
forward in breeding. With a full
line of colors, Prism begonias
were selected for vigor and,
most importantly, for flowers
held above the foliage. This
combination of features makes
them a superior option for
homeowners and growers alike;
more flowers on display for
gardeners, fewer disease issues
and losses due to buried blooms
for growers.
CULTURE GUIDELINES
As with other tuberous
begonias from seed, Prism
begonias have a very long crop
cycle from seed to finished
plant, and there are very specific
requirements for consistent
success, so growing from
seed is only recommended for
the most experienced young
plant producers. However,
if you are sowing seed, it is
always important to remember
to keep freshly sown seed in
high humidity conditions, until
cotyledons are fully emerged,
to prevent the newly emerged
seedlings from drying out.
Once cotyledons are expanded,
the humidity levels can be
gradually reduced. Light is also
necessary for germination, so
do not cover the seed, and make
sure the days are over 12 hours;
14-hour days are recommended,
even as seedlings.
Prism begonias are long-day
plants and need at least 14 hours
of daylight to continue healthy
growth, otherwise they will begin
to divert resources to tuber
development. Night breaks are
effective, but daylength extension
is recommended. Maintain
warm growing conditions to
prevent temperature stresses and
encourage healthy full growth.
Moderate rates of fertility (150ppm
nitrogen) are recommended
with occasional clear water to
leach out accumulated salts but
avoid high levels of ammonium to
prevent excessive foliage growth.
Growth control can be
achieved by proper scheduling
and growing conditions,
but can be assisted using
chemical growth regulators
like chlormequat at 250ppm.
Extensive trialing should be
performed before committing to
widescale use of any chemical
growth regulators.
If you produce tuberous
begonias, or if you have in the
past and had trouble, Prism
begonias are the new series
for the efficient, economical
grower that wants to provide the
absolute best quality finished
plants for their customers. Seed
is commercially available from
your preferred seed broker,
and young plants are widely
available at the most popular
suppliers nationwide.
Bart Hayes is sales manager for
Westhoff/PAC. He can be reached
at bart.hayes@westflowers.de.
Prism Series
http://www.GPNMAG.COM
January 2020

Table of Contents for the Digital Edition of January 2020
