Native Plants

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

Tuesday - June 18, 2013

From: Magnolia, TX
Region: Southwest
Topic: Pruning, Shrubs
Title: Pruning Ageratina havenensis from Magnolia TX
Answered by: Barbara Medford

QUESTION:

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 came through the mild winter without any extra watering. It has been putting out blooms, one or two branches at a time, since late February. Should I be pruning back the branches that have bloomed so as to guarantee enough new growth for it to bloom all over in the autumn, or should I be glad it bloomed at all?

ANSWER:

This plant appears in our Native Plant Database as Ageratina havanensis (Havana snakeroot); Eupatorium havanensis is an older name, now considered a synonym. As you can see from this USDA Plant Profile Map, it grows somewhat west of Montgomery County, and we are not sure the soils would be similar. However, if you are growing it, it must be okay there.

From our webpage on this plant:

"White mistflower provides late summer and early fall color. Blooms best and appears bushier if severely cut back each winter."

That keeps you from deciding whether to cut back the present blooms in hopes of more blooms later. It should continue to provide color until early Fall and then can be pruned back hard in November to January. Perhaps the extra blooming is the result of more rain and lusher soils in your part of the state.

From the Image Gallery

Shrubby boneset
Ageratina havanensis