I can't think of a plant I hate more than the poinsettia. My intense hatred of this tropical plant, native to Mexico, has little to do with its association with Christmas and holiday cheer. My hatred of this plant stems from my childhood and spotting it in the windows of burger joints, Laundromats and storefront offices around Chicago. Even before I knew I liked plants, I knew I hated poinsettias
By the time summer rolls around Chicago these poinsettias are tall spindly things with barely two leafs. They grow desperately towards florescent light fixtures or smash their ugly faces against windowpanes in a pathetic attempt to either illicit sympathy from passersby or to get some light. A plant that doesn't know when to give up the ghost will need some help in passing onto the big greenhouse in the sky.
How to Kill a Poinsettia in Three Easy Steps
Unfortunately for the poinsettia, and its haters, most people who buy them don't know how to care for them so they remain lush, healthy plants. So, here are some tips on how to kill a poinsettia that someone either gave you for Christmas or that you bought in a misguided attempt to decorate your house, office or small business.
1. Cold. Being tropical plants they don't like cold temperatures. Place it on your deck, patio, balcony, fire escape or garden today. The snow covers a multitude of sins, even plant murder. For the faint of heart; placing it in a drafty window or near a door where it will be subjected to regular blasts of cold air works too. It is a slower death, but gets the job done.
2. Drown 'em. Poinsettias like even moisture, not too soggy and not too dry. When you're watering your houseplants give your poinsettia extra water. If they still have that ridiculous foil wrapping around the pot pour a bit of water in there to ensure soil remains constantly wet.
3. Darkness. Place it dark place where it will not get any sunlight or be able to grow upwards to any light fixture. The leaves will soon drop and you can throw it away because everyone knows that a houseplant with no leaves is pretty much dead.
Any one of these three steps will lead to a quick death for most poinsettias. Combine two of the steps if you notice your poinsettia isn't getting the hint. I omitted allowing them to dry out as a method of poinsettia murder. A droopy poinsettia may illicit a sympathetic watering from someone who doesn't know you're purposefully trying to kill your poinsettia. Alternately, you can go on vacation and forget to put anyone in charge of your poinsettia or put it in the care of someone with a black thumb. When you come back from your vacation you will be rested and poinsettia free.
The Poinsettia FAQ on the University of Illinois Extension has good info for those who actually like poinsettias.