En Español

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?


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

Sunday - September 28, 2008

From: Iredell, TX
Region: Southwest
Topic: Pruning, Trees
Title: Pruning native Senna lindheimeriana
Answered by: Barbara Medford


I asked a question about pruning a Texas Senna tree. The Texas Senna I have is either a S. wislizenii or a S.lindheimeriana. It is a beautiful tree that I purchased at a Texas Native Plant nursery. Like I said in my previous email, it is about 7 to 8 feet tall and and about 7 feet across. It has small green leaves and is very bushy and full. My question was how and when do I prune it. Can you please give me some information on this?


Oops, sorry, you're absolutely correct. Our mistake was to look for the "Texas Senna" in our Native Plant Database, and it wasn't found under that name. The "Texas Senna" we did find was a non-native. This is the problem we run into when retailers name their plants without regard to botanical names. Fortunately, you apparently got (and saved) a label with the proper botanical name.

Senna lindheimeriana (velvet leaf senna) is a tender perennial and considered a sub-tropical herbaceous plant. Senna wislizeni (Wislizenus' senna), on the other hand, is referred to as "shrubby", has thorns, and can apparently take lower temperatures. 

We did not find any pruning instructions for either plant; however, we did learn that in colder temperatures, Senna lindheimeriana (velvet leaf senna) will die back, but will come back from the roots. For that reason, we would suggest that you let it run through its blooming season (apparently October is the end), and then trim it back pretty thoroughly. When we prune a plant like that, we always leave stalks sticking up 8 to 10 inches, just so we'll know where it is. If you are expecting some pretty cold weather, it would be a good idea to mulch the roots. The plant should begin to come back from the roots in Spring, and will probably grow bigger and more lush for having been trimmed back. 

If you believe that what you have is Senna wislizeni (Wislizenus' senna), we would still recommend pretty good pruning, but maybe not down as low. And, in fact, you might want to wait until late Winter, when you don't expect any more hard freezes, to do that pruning. If you prune it too soon, and there is a hard freeze, it could damage new growth starting to emerge. 


From the Image Gallery

Lindheimer's senna
Senna lindheimeriana

Lindheimer's senna
Senna lindheimeriana

Canyon senna
Senna wislizeni

Canyon senna
Senna wislizeni

More Pruning Questions

Care for penstemons in South Jordan, UT
June 21, 2009 - I have Firecracker Penstemons and they bloomed beautifully this year. How do I trim them and when? Will they continue to bloom throughout the summer?
view the full question and answer

Survival of native yaupon in The Woodlands, TX after hurricane
September 25, 2008 - One of my large native yaupons trees (8ft) fell away from a group during the hurricane. I have uprighted and tied it off for stability. Now the leaves are all brown and falling. Is the tree dead or...
view the full question and answer

Removal of honeysuckle bushes from Coaldale Alberta Canada
July 30, 2010 - I have 2 honeysuckle bushes that I want to get rid of. I am wondering if Honeysuckle bushes have very deep roots (are they hard to dig out?) I am 70 years old and didn't know if I'd be able to dig ...
view the full question and answer

Need help with pruning my Anacacho Orchid tree.
January 04, 2010 - We have an Anacacho Orchid Tree which has done so well in its location that we will need to prune it back. Please advise how much we can prune it and what time of year to do so. Thank you
view the full question and answer

Passiflora and Leucophyllum together in Texas
April 23, 2015 - I've got a Passiflora incarnata that has self-propagated around a cenizo sage. My question is, will the passionflower vine choke out or otherwise damage the cenizo? Do I need to cut back the vine? ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center