Posted by: Alison O’Connor, Larimer County Extension
I’m sure you’ve all heard the warnings about poinsettias—don’t
let them dry out, don’t let them get cold, be sure to buy them on a warm day so
they don’t suffer from cold injury as you walk to your car. There are a lot of
care instructions that accompany that gorgeous red, pink, white or bi-color
holiday plant. But are poinsettias as wimpy as we think they are? Do they
really wither with a slight cold breeze? Can they withstand freezing
temperatures? This is what I wanted to find out, so with my $0.99 poinsettias I
purchased after Thanksgiving (yes, it’s a deal and no, the grower doesn’t make
any money), I essentially tested the limits of these colorful plants to see how
far I could push them.
Poinsettias (Euphorbia
pulcherrima) are a member of the euphorbia family, which means they are
related to leafy spurge (ugh), castor bean (highly poisonous), croton and the
rubber tree. It also means they contain a milky white sap that oozes when plant
parts are broken and discourages grazing animals. The scientific name comes
from Euphorbus, named after the Greek physician who cared for King Juba II (50
B.C. to 19 A.D.) Pulcherrima
translates to beautiful or handsome. Many of the euphorbia plants are
attractive with colorful bracts (like the poinsettias) or leaves (croton).
But back to the experiment... Like you, I take extreme
caution when transporting poinsettias from the store to my car and place them
in my home in a non-drafty location. I water them regularly and make sure the
water drains from the plastic sleeve surrounding the pot. The poinsettias do surprisingly
well in my home, even though we keep our heat around 60 degrees, and last for
several weeks past Christmas. Usually I get sick of watering and caring for
them and they end up in the trash before they start to fade. But as I mentioned
above…all those warnings! Do these plants need to be babied as much as we
think?
So I bought 15 poinsettias and put them in the greenhouse
and started the treatments: drowning (sitting in standing water constantly),
drought (no water) and placed in a drafty spot. I looked at treatments using
plastic sleeves when the plants are outdoors and no plastic sleeve (to try to determine
if the plastic sleeve does anything when you walk outside). I put the sleeve
and no sleeve plants outside when it was a balmy 21 degrees outside and left
them there for 12 minutes (figuring that’s a long time for a person to walk
from the store to their car).
In short, you can probably guess which ones looked the
worst. Yes, the drowning and drought bit the dust, but it took them a few
weeks. Clearly, water…either too much or too little…is not a friend of the
poinsettia. The plants put outdoors looked fine. In fact, they showed no signs
of cold stress at all. They didn’t even flinch! The plants put in front of the
draft were also fine, but after four weeks, they were much smaller in size than
their counterparts. Interesting!
'Nuff said. No water for 4 weeks. |
Sitting in standing water for 4 weeks. |
Plants in a drafty spot were much smaller in size. |
Cold treatment (12 minutes at 21 degrees) did not affect these poinsettias. |
Sleeve or no sleeve. Poinsettias appeared to be unaffected by cold. |
Because I was bound and determined to see something on how cold weather affects
poinsettias, I did another round with new plants. These were generously donated
from the CSU student poinsettia sale (thanks Mike and Dr. Newman!). A couple
weeks ago it was horribly windy and very cold. Perfect! The wind was howling at
30mph and it was 32 degrees outside. I left them outside in these elements for
20 minutes—much longer than I would have lasted…and I’m not a Zone 10 plant.
Again, nothing! No damage to the bracts from the wind. No
leaf tattering. No signs of stress, except for maybe a bit of leaf tip burn.
I’m impressed. And flummoxed. My conclusion to the Great
Poinsettia Experiment? They appear to be much tougher than we give them credit
for. And quite scrappy. It’s no wonder that they are so popular and over 34
million are sold in the United States each year. In fact, it’s the number one
potted plant (take that, Easter lily). My hat’s off to you, poinsettia.
Maybe snow would have been a good treatment... |