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

Trimming damaged leaves on agaves
February 05, 2009 - Some of the leaves on my agaves are damaged. Can I cut them off? If yes, how can I prevent the wound from becoming infected? Thanks.
view the full question and answer

Wholesale dry yucca trunks and branches from California
January 29, 2012 - Where can I buy wholesale dry yucca trunks and branches? I have spent the last hour looking for them and can only find nurseries and decorative branches.
view the full question and answer

Insects on yucca from Ft. Worth TX
April 05, 2012 - I have a plant labeled Yucca Soft Leaf recurvifolia that I planted about 5 years ago,& was beautiful until last summer when it became infested with thousands of fast, tiny, dark insects. I sprayed wit...
view the full question and answer

Eliminating prickly pear
March 24, 2007 - What is best practice for eliminating 100+ acres of dense prickly pear?
view the full question and answer

Use of Century Plant bloom as indoor decoration
December 09, 2008 - Mr. Smarty Pants, After living in Arizona and now San Antonio, I am in search of a Century Plant Bloom. I cannot have an evergreen because my cats climb them. I would shellac the stalk and blooms a...
view the full question and answer

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