Rent Shop Volunteer Join

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Wednesday - December 02, 2009

From: Marble Falls, TX
Region: Southwest
Topic: Cacti and Succulents
Title: Potted crown of thorns cactus cold tolerance in Marble Falls, TX
Answered by: Barbara Medford

QUESTION:

I have a large potted crown-of-thorns cactus. Can it remain outside this winter in the Texas Hill Country?

ANSWER:

When we originally received this question, we went to our Native Plant Database and found Koeberlinia spinosa (crown of thorns), which grows natively in far South Texas and the Big Bend area, where temperatures are warmer than they are in Central Texas; however, this plant is known to be hardy to 0 deg. F. So, we replied that we thought the potted plant would be all right outside. Turns out we let the common name curse keep us from finding the plant actually referred to in the question. This old-fashioned houseplant, Euphorbia milii, crown of thorns, is more likely the plant about which the inquiry was sent. 

The Lady Bird Johnson Wildflower Center is dedicated to the use, care and propagation of plants native not only to North America but to the area in which it is being grown. This puts this native of Madagascar our of our realm of expertise. We can tell you that while we said the Koeberlinia spinosa could be wintered over outside in a pot in the Hill Country of Texas, we find that the Euphorbia milii is only hardy from Zones 9b to 11. Central Texas is generally Zone 8a. The plant itself would be threatened by a hard frost in this area, and certainly a plant with its roots exposed in a pot would be even more likely to be damaged by cold weather. Euphorbia milii should be treated as an indoor potted plant over the winter. Here is more information on this plant from Floridata and pictures from Google

One further note: neither the Koeberlinia spinosa nor the Euphorbia milii are cacti. Koeberlinia spinosa is a member of the Capparaceae or Caper family, while Euphorbia milii is a member of the Euphorbiaceae or Spurge family.

 

More Cacti and Succulents Questions

Failure to bloom of red yucca from Lago Vista TX
April 09, 2013 - I am in Lago Vista - trying to find out why I can't get my red yucca to bloom. The first year they were great and now after two or three years - no measurable spikes have shown up. HELP!
view the full question and answer

Starting yucca from seed from Austin
December 24, 2012 - I would like to start a soft leaf yucca recurvifolia from seed. Is that possible? Also, I've looked for seed on dried flower stalks, and I'm not sure that what I'm finding is the seed, and I ...
view the full question and answer

Can I save my century plant by cutting the flowering stalk in Austin, TX? Probably not.
April 28, 2010 - Our century plant is starting to sprout it's flower (four feet). If we cut it down can we save the plant? Thank you.
view the full question and answer

Information about prickly pear cactus for school project
October 19, 2012 - Hello my name is Case Danzeiser. I go to a middle school called Clint Small Middle School in Austin, Texas. We are doing a species study on a native Texas plants and animals. I choose to study the pri...
view the full question and answer

Sun loving plants for flower bed by the pool in Weatherford Texas
October 03, 2011 - We have a 40' long x 2 1/2' wide flowerbed along our pool. It is in full sun with the pool deck across the front and a 6' privacy fence across back. Also, the level of the bed is 18" below the l...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.