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
Not Yet Rated

Monday - August 22, 2011

From: Three Rivers, MI
Region: Midwest
Topic: Diseases and Disorders, Watering
Title: Watering Houseplants with Soapy Water
Answered by: Brigid & Larry Larson


I accidentally watered my house plants with a container that had a some dishsoap in it. Will they be okay? One of the plants is a 20yr old cactus, with small roots.


Mr Smarty Plants thinks your plants will likely be OK - - but you didn't tell us how much soap was used. 

So, we'll give you some examples of how soap is used on plants and maybe that will help you decide about your situation.

We're having a serious drought here in Texas right now and many of us are using grey-water to water our plants as a water conservation effort.  The plants are fine with this and some of them thrive on this  regimen.  Here's a conversation from Wiki-Answers where this is discussed.

At about the same concentration of soap, soapy water is often recommended as a natural approach for bug control.  Here are webpages from manipedia and evergrow where this is discussed. Mr Smarty Plants recently recommended soapy water for contolling Cochineal insects on Cholla Cactus and for Powdery Mildew control.

Larger concentrations of soap are used for opening conpacted soil and aiding water penetration.  Mr Smarty Plants has recommended soap for opening hydrophobic soil.

So - Your chances of the plants being OK are pretty good; perhaps you can remember these applications for soapy water for later use. 




From the Image Gallery

Cane cactus
Cylindropuntia imbricata var. imbricata

Rock rose
Pavonia lasiopetala

More Watering Questions

Replacing Drought-Stricken Cedars
January 16, 2012 - Hello, I live in Williamson County on a couple acres. We have several dead cedars as a result of drought; we're reluctant to cut them down because many of them provide a friendly barrier between us...
view the full question and answer

Deer resistant plants from New Braunfels TX
August 31, 2012 - I have a 1/2 yard covered by a tree, shady. Bermuda grass previous owner planted has all turned brown this summer. I don't have lots of money to work with but would love to landscape that side of fr...
view the full question and answer

How to care for newly transplanted Live Oak.
July 02, 2009 - I planted 3 B & B, 6" caliper live oaks in February and they lost most of their leaves during the normal time but when the new leaves grew back the amount of leaves were quite a bit less. I have th...
view the full question and answer

Root rot and transplant shock in Texas betony
July 13, 2006 - Texas betony is supposed to be drought resistant but also likes to be kept moist, but I have had trouble getting it established. These seem to be undemanding plants I have had entire stems dry up and...
view the full question and answer

Ailing Tecoma stans from Phoenix AZ
August 24, 2012 - I have several young Tecoma plants in my Phoenix, AZ garden. I planted them in June and have tended to them over the summer. They are watered twice daily. On some of the plants, I've noticed two oddi...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center