69 (January/February 2002)
Begonias as Standards
by Brad Thompson
As a grower with limited growing space, I'm always
looking for novel ways to grow begonias. I try to use my space effectively
for maximum show and squeeze in as many varieties as possible. Over the
last few years I've grown begonias on moss covered boards, on trellises,
in wall pocket type bags as ways to use space. Lately I've been working on
growing begonias as standards. In case you don't know what I mean by a
standard, this is a method of growing a plant into a treelike form with
one central stem and full at the top. This article is to share some of the
methods and which varieties are likely to make the best standards.
The hardest part of making a standard is figuring out
what begonia to use. Here are qualities to look for when choosing the
plant. You need to pick varieties that are balanced between easy blooming
and good branching. If you choose one that blooms too heavily and rarely
branches, you'll have great difficulty in getting it to conform to a
standard. On the other hand if you choose one that branches really well
but rarely blooms you'll end up with a standard that never blooms. No
sense in putting in all that work on a plant that doesn't perform.
Another important trait is a plant that will grow one
sturdy straight stem, but that will also put out manageable side shoots
when pinched out. Some begonias such as B. 'Sophie Cecile' would put up a
nice sturdy main shoot, but you might have trouble keeping it in check
since it's such a strong grower. Also, the amount of pinching required to
make it conform would almost guarantee that you'd never get any blooms
since it's a shy bloomer to begin with. At the opposite, a plant such as
B. 'Tom Ment' would make a lovely standard if only you could get a
stem to grow two or three feet tall that would be sturdy enough to support
all future growth on the plant.
There are many choices; in this article I'm trying to
refer to begonias that nearly everyone is familiar with. A cane that would
be nearly perfect in traits to grow as standard would be B. albo picta.
It can send up nice sturdy shoots, sends out nice side growth when
pinched, and still blooms well. An example of a shrub that has nearly
perfect traits is B. echinosepala. There are many, but I'm listing
these two as examples to follow when choosing. Begonias that probably
wouldn't make good standards are Semperflorens or Semperflorens hybrids
such as B. 'Christmas Candy'. They bloom well, but are nearly
impossible to branch once they start blooming.
Creating a standard is a fairly simple process, but you must be
prepared to spend a year or two growing one to full glory. The first year
will be spent mostly getting it to the height you want and the second year
will be spent pinching it to make it fill in.
Brad Thompson's hybrid B. 'Suspicion' (B.
'Jumbo Jet' x 'Dumbo').
I try to start cuttings specifically to make standards
with. For this purpose, I try to find those bad cuttings that we normally
throw away, those that have bloomed up the stem. For normal purposes these
cuttings are not good because any plant you create from them will have no
basal growth when planted. For making standards, a cutting that won't make
basal growth is perfect.
Once the cutting is rooted, pot it up as you normally
would. It helps to put in a tall stake right from the beginning so you can
keep the plant tied up straight as it grows. It will also help you
remember that you're making a standard. I can't tell you how many times
I've forgotten and pinched the tip. Continue to tie the plant to the stake
as it grows and remove any side growth that might try to pop out. One
important note, make sure you don't tie the stem too tightly. This main
stem will grow larger with time and the tie can cut right through it. The
flexible stretchy plastic ties like you would use on tomatoes work best to
avoid this problem. Later when the plant is mature you can switch to the
wire plastic ties. It's best to keep the standard staked it's entire life
whether the main stem seems really sturdy or not.
You can grow the standard to whatever height you
choose, two to three feet is usually a good height, but you can make it
taller if you like. Take into account that it will end up taller after you
pinch it out. I encountered a problem I hadn't considered when I made
them, that they were too tall to fit in my covered pickup when I wanted to
take one to a show . When the stem is as tall as you would like, pinch out
the main growing tip. Make sure there are side buds where you pinch out
though. If it's blooming heavily and you pinch it, it will branch out down
lower wherever there are side growth nodes. You can try growing it in less
than the best light during this process to keep it from coming into
As the side shoots come out, let them come out a few
nodes and then pinch them again. The first year you should keep up this
pinching every few nodes until you have a shapely plant and not worry
about blooms. Any new basal growth that comes up should be cut completely
out at or below the soil line.
For potting, at first it should be kept a little
under-potted to avoid overwatering. If you find it hard to keep upright,
either use a clay pot or set the plastic pot inside a clay pot for
stability. As it matures the standard should be treated like you would any
begonia with regular fertilizer and so forth. Determine future pot sizes
by how much growth is at the top, not by how tall the stem is. The pot
should be about one third the size of the top growth at its most mature.
You can also determine that it needs a bigger pot if it starts drying out
faster than other plants around it.
Pinching will be a yearly requirement to keep the
standard in shape. In the spring you may also need to do some pruning to
keep it in line. Make sure not to prune back so hard that you remove most
of the good nodes. If you prune really hard you may undo part of the
previous year's work.
Standards make really spectacular additions to your
gardens and collections. If you're trying it for the first time, since it
is a long process, do lots of different varieties at one time so you won't
be as disappointed with failures. It will take some experimenting to find
good canes and shrubs to use. Some might seem like good choices, but their
branches aren't strong enough to support themselves in the tree form.
Others might seem fine at first, but turn out to be varieties that are
prone to die back. Remember, the plant has to live it's entire life off
one stem so it has to last long time. I made a wonderful standard of
B. 'Laura Engelbert' one year, but it was only great for one year. It
died back all the way to the main stem over that next winter so although
it was beautiful, it wasn't long lasting and not worth doing again. Hope
you give standards a try, they are fun and rewarding, even if they do take
a little work.