En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Getting a senna to fill out from Irvine CA

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.

Need help with plant identification, visit the plant identification page.
 
rate this answer
Not Yet Rated

Thursday - May 30, 2013

From: Irvine , CA
Region: California
Topic: Pruning, Shrubs
Title: Getting a senna to fill out from Irvine CA
Answered by: Barbara Medford

QUESTION:

I have a Senna of some kind, started from a seed by a friend. I got it as a small,six in high) seedling. After two years it is now blooming beautifully, but is a single thin stem 4 feet tall with very few short side branches. It is bending over and very spindly. How can I prune it to get a full bush or a branching tree shape, anything but a tall, thin, bent over whip?

ANSWER:

There are two members of the Senna genus native to California. One is Senna armata (Desert senna) which is native right next to Orange County (USDA Plant Profile Map) and Senna obtusifolia (Java-bean), native relatively near Orange County (USDA Plant Profile Map).

We did a lot of looking trying to find out about the senna plant, considered a subshrub. Our Native Plant Database webpages on the two native to California as well as the rest native to North America yielded very little information except that it was often considered a weedy pest. It is a member of the Fabaceae (bean) family. Here are some photos of Senna armata (Desert senna) from CalPhoto. If they are accurate, you should have a lot of flower-bearing stems instead of only one. However, two years is not a very long time for a shrub to mature.

The nearest we could find to a description of a plant is from Wikipedia:

"Senna armata is a species of flowering plant in the legume family known by the common names spiny senna and desert senna. It is native to the desert regions around the intersection of Nevada, Arizona, eastern California and northern Baja California, where it grows in sandy and rocky habitat, such as arroyos. It is a shrub growing up to a meter tall, its grooved, branching stems often narrowing to thorns at their tips. The spiny branches are coated in tubular hairs which help protect it from hot desert air. The spine-tipped leaves are each made up of two to four pairs of small leaflets. The leaves are ephemeral, dropping soon after emerging, leaving the shrub naked most of the time. Flowers occur singly or in small clusters in leaf axils. They are fragrant and showy, with five petals in shades of yellow to salmon pink, each measuring roughly a centimeter long. The fruit is a legume pod up to 4 centimeters long."

Just at a guess, with no better information, we would say your plant may simply not be mature yet. It is a desert plant, so it needs little water, no fertilizer and lots of sun. Any of those not observed, especially the fertilizer, can inhibit the blooming. One last note -almost any plant grows more quickly from root cuttings or division than from seeds.

We would suggest pruning back any dead growth or wilted flowers. Plants all need to bloom in order to reproduce theselves, so if the plant is in a good place for it to grow, it should be inspired to put on more blooms.

 

From the Image Gallery


Desert senna
Senna armata

Java-bean
Senna obtusifolia

More Pruning Questions

Cutting Juncus effusus back from Bellevue WA
November 18, 2010 - I read your posts about Juncus effusus and just have one follow-up question. When is the best time to cut them back to the ground - before winter or early spring? I live in the Pacific NW. I recent...
view the full question and answer

Sprout from a non-native sago palm in Poinciana FL
October 16, 2013 - I have two mature (10 years old)sago palms. One of them sprouted a new "head' at the top of the trunk. It is competing with the original one. It is not a pup coming from the root area. Can I cut it ...
view the full question and answer

Pruning Ageratina havenensis from Magnolia TX
June 18, 2013 - I planted a Eupatorium havanense last year here in the last sandy finger of the piney woods; it gets full sun in a well-drained raised bed, where it flowered well. I pruned it fairly close, and it cam...
view the full question and answer

Pruning native Senna lindheimeriana
September 28, 2008 - 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. ...
view the full question and answer

Transplanting large Silverado Sage bushes from Mesa AZ
August 19, 2013 - We just bought a condo with three Silverado Sage, each one is 6-8 ft tall, trained to grow as "trees" with bare branches for the bottom 4 feet or so, and beautiful flowering branches on top. They ar...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center