Quick Tip from Neil – October, 2007

Poinsettias are tropical by nature. They were brought to the U.S. from Mexico and soon became favorite holiday flowers. They are photoperiodic. That’s a botanical term referring to the fact that they measure the length of the nightly dark period. When nights become long enough, a flowering hormone is produced telling the plants to change from vegetative to reproductive growth. In nature, that normally occurs around Christmas, so it’s no small coincidence that they’re so widely available this time of year.

Here are some brief facts on the plant:

Be careful transporting poinsettias when the weather is cold. They can withstand only a few moments of sub-freezing weather (probably less than 30 seconds). If it’s near or below 32 degrees, cover your plant to trap warm air around it, and have the car warmed up and waiting.

Keep your plant cool and bright. It was grown in a greenhouse where night temperatures were in the mid- or low 60s. Keep it away from hot drafts.

Do not allow your poinsettia to wilt. If it wilts badly it will start shedding leaves a few days later and eventually you’ll end up with a stark, palm-tree of a plant.

Your plant will need no supplemental feeding while it’s in bloom.

If you want to rebloom your plant next year you’ll want to cut it back almost to the soil line once it has quit flowering. Repot it into a large container. Given the best growing conditions, poinsettia plants can grow to 8 to 10 feet tall and wide in just one growing season. It will need a large pot! Fertilize it each time that you water it next year. Use a dilute solution of a complete-and-balanced, water-soluble plant food. Pinch out its growing tips every few weeks to keep it compact and well branched.

Did you know:

Poinsettias are not poisonous! Most folks assume that they are, but research done 30 years ago by The Ohio State University confirmed that, indeed, they are not.

Poinsettias are closely related to pencil plant and crown of thorns. The Euphorbia plant family is one of the most diverse in the world. Entire plant encyclopedias have been written on them. See related information in Jimmy Turner’s Plant of the Month, also in Q&A, this issue.

All poinsettia flowers are yellow. Not red. Not pink. Not white. Yellow. Look more closely. What you may have been calling “petals” are actually floral bracts (modified leaves). You can see how they have developed from normal leaves by observing the gradual change in their shapes as you advance up the stems nearing the floral bracts. The true flowers are those little taco-shaped, golden yellow things in the centers.

Posted by Neil Sperry
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