En EspaŅol

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
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
1 rating

Monday - June 28, 2010

From: Mountville, PA
Region: Mid-Atlantic
Topic: Water Gardens, Seasonal Tasks
Title: Can Juncus effusus winter outside in Mountville PA?
Answered by: Barbara Medford


If we have the juncus effusus spiralis outside in a small pond and you say to let it outside in the winter does that mean we should let it in the pond? thanks for your time


Juncus effusus (common rush) is native to nearly all the states and some Canadian provinces in North America, including Texas and Pennsylvania.  We are a little confused; was your question should you leave it outside and leave it in the pond? When you say "let" we think more of letting the dog in, so should you let the plant in? 


Juncus effusus (common rush)  is hardy from USDA Zones 4 to 10. It appears that Mountville PA, Lancaster County is in Zones 6a to 6b, so the plant should do fine there outside. Juncus effusus 'Spiralis' is a selection for horticultural use, low growing with strongly spiraling stems. According to this Floridata article on Juncus effusus, it is really better to allow the plant to freeze back, remaining outdoors during the winter, because the stems (there are no leaves) will come back much stronger and better-looking. In milder climates (such as indoors) the stems will get brown and less attractive-looking, and will need to be trimmed. However, this page from Blue Stem Nursery on Lesser Corkscrew Rush refers to it as a plant that can be kept in a terra cotta pot and double as a winter houseplant. We would imagine the soil in the pot would need to be kept pretty moist, but we did see a number of illustrations of the plant in pots and indoors. 

As to whether to leave it in the pond outdoors in winter, that probably depends on how hard your pond freezes. The plant needs to be kept moist, frozen or not, so you will have to use your best judgment on whether to pot it up and bring it where you  can water it outside if it's not getting enough moisture, or bring it inside and give it moisture. 

Pictures of Juncus effusus 'Spiralis' 



More Seasonal Tasks Questions

Time to cut back Turk's Cap in Austin
January 27, 2011 - I did not find my question answered in the database. My question is: When is the best time to cut back Red Turks Cap? I live in Central Austin.
view the full question and answer

Cutting Back Perennials in the Fall?
November 13, 2013 - We have large beds of flowering native perennials that we planted around our house as part of a landscape conservation plan (various Joe-Pyes, goldenrods, turtlehead, blazing star, brown-eyed Susans)....
view the full question and answer

Trimming native Yucca filamentosa for winter in Illinois
October 18, 2008 - I live in northern IL and I have approximately 5 yucca plants, Adams needle, my question is do I need to trim them down for winter for best growth the next year?
view the full question and answer

Arrows and Hunting Dogs in Kentucky
December 09, 2009 - Mr. Smarty Plants--Is it normal for our arrowwood viburnum to give off a musky odour in the late fall? The smell reminds me of a wet hunting dog.
view the full question and answer

Deadheading Mexican hat to produce more blooms in Austin
July 05, 2010 - I have several Mexican hat (rudbeckia) plants growing wild in my yard. Would deadheading now give them a second flush of bloom in fall?
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.
© 2015 Lady Bird Johnson Wildflower Center