Yard
and Garden
May
16, 2015
Q. All of my front porch potted
flowers, except my wax begonias, are thriving (photos e-mailed). Even my
geraniums, which you cannot see in the picture, because they are hanging in a
basket, are doing well. However, though still alive, I have not noticed any
growth with the begonias since I planted them about three weeks ago. Further,
there is a brownish coloring appearing around the edges of the leaves.
The plants get the afternoon sun in southeastern New Mexico and I give them a
good dousing with the hose when I get home from work. However, I think I may be
overwatering the begonias. Do they require less water than other popular
flowers? Thanks.
Tim H.
A.
Tim, thank you for the photographs, they are good photographs and very
helpful. Begonias (and geraniums) are succulent plants and can indeed
suffer from overwatering. Based on the pictures, that is one possibility
for your problem.
Your pictures show that the plants have many flowers. An old
recommendation is to choose bedding plants with few or no flowers since the energy
of the plant is directed at producing flowers instead of growth. The
bedding plants may have been treated with plant growth regulators to keep them
compact and encourage flowering. Since people prefer to purchase plants
with flowers to be sure they have the flower colors that they prefer, this
makes sense, but the growth inhibition may continue for a while after
transplanting. This may be part of the situation with your begonia
plants. While these plants are growing more slowly, their water requirements
are less. With succulents like the begonias, this may contribute to an
overwatering problem. The other plants are not succulents and do not
appear to be as strongly inhibited (except the geraniums that are not in the
photographs, but they are probably larger and perhaps not treated with growth
inhibitors or as strongly affected as begonias).
I think I can see the exposed edges of peat pots in the close up picture of the
pot containing the wax begonias. I do not see that in the pots with the other
plant species (but then there is no close up picture of those). The exposed
edges of the peat pots can serve as wicks drying during the day and exposing
the plant roots to accumulated salts (minerals left as the water
evaporates). The browning edges of the wax begonias may be due to salt
burn mediated by the exposed peat pots. This salt damage to roots can result in
root death and root rot. There appear to be some symptoms of drying in
some of the leaves of the begonia plants. This may be due to loss of
roots, even when the potting soil remains moist. Once again the succulent
nature of the wax begonias can enhance the problem with root loss and
development of root diseases.
Reduce watering a little, perhaps watering some in the morning and then a
little more in the evening, to see if this will help the plants. Continue
watering the other plants as you have been watering since they are growing
well.
Wax begonia leaves have an interesting characteristic of developing a frosty,
glazed (dull green) appearance when the plants are in need of water. Let
that be a guide to direct your watering. The begonias and geraniums, more
than the other bedding plants, can tolerate and even benefit, from a little
drier growing conditions. Do not begin fertilizing until the plants have
established their roots and begun growing more foliage.
Send
your gardening questions to Yard and Garden, Attn: Dr. Curtis Smith, NMSU
Agricultural Science Center, 1036 Miller Rd. SW, Los Lunas, NM 87031. You may also
send to cwsmith@nmsu.edu or leave a message at https://www.facebook.com/NMSUExtExpStnPubs. Curtis W. Smith,
Ph.D., is an Extension Horticulture Specialist, retired from New Mexico State
University’s Cooperative Extension Service. NMSU and the U.S. Department
of Agriculture cooperating.
