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

Wednesday - August 19, 2009

From: Austin, TX
Region: Southwest
Topic: Watering, Trees
Title: PVC pipes for irrigation in ground in Austin
Answered by: Barbara Medford


Mr. Smarty Plants,What are your thoughts on installing PVC pipes into the ground around trees and shrubby trees? A classmate's grandmother had a pipe pushed or pounded into the ground near her special rose bush because she thought the water would get to it without being wasted; holes were drilled into the pipe. For many years her water well was her sole water supply and given our exceptional drought I am beginning to think she was onto something. My soil--if you could call it that---is caliche. I don't have a sprinkler system. I use soaker hoses or bubblers whenever I water my trees and shrubs and I want the water to go as deep as possible with as little lost to evaporation as possible. The trees and shrubs I've planted are mulched with several layers of newspaper and recycled tree bark. Should I mulch around my older established trees? Thanks,Trying to be water wise in Central East Austin


We think you are already doing a bunch of the right things for xeric landscaping during our extreme heat and drought in Austin. The perforated PVC pipe you are considering is ordinarily used for "French drains" in which an area does not drain well because of a slope or a roof draining directly onto it. It is used horizontally, and usually buried in a fine gravel to permit that extra water to disseminate over a wider area, and not drown the roots of the plants. We think it would be more trouble and expense than it is worth to drive those pipes vertically into the ground. In the first place, as you pointed out, your soil is caliche-it doesn't take well to having anything drilled down into it, including an oil rig.  In the second place, we're concerned that there would be damage to already established roots as the pipe goes down, and root damage is the last thing you want. And don't forget, most roots, including those of very large trees, are in the upper 12 inches of soil. If you drive, say, a 36 inch pipe down there, the water is going to rush toward the bottom by the force of gravity, with probably very little coming out in the actual root area, and the rest going down to sit out of range of roots in the subsoil. 

As far as we can see, the bubblers and soaker hoses are probably the most efficient method you can use. Right now, a lot of people are asking about watering the roots of their large trees, and we have been suggesting that they run sprinklers on the root area out away from the trunk. On a large tree, this can be fairly far out, even beyond the dripline or shade line of the canopy. However, you do lose water to evaporation when you use sprinklers. While we recommend pushing a hose down into the soil around the roots of bushes, and letting the water dribble very slowly, that is really not practical with a large tree. You could use some combination of soaker hoses and sprinklers to cover a lot of the root area of trees and then, certainly mulch is always a good thing over extended roots. It helps in several ways: if the shade is deep, you're probably not going to have much luck growing anything under that tree, and mulch is attractive and protects the roots from heat as well as holding in moisture. Do not heap the mulch around the trunk, that will make it vulnerable to fungi and rots. 

And we really, truly do believe that it will rain again. The job now is keeping things alive until it does.



More Trees Questions

Will a Texas Mountain Laurel thrive in a 4'x4'x4' brick planter. pl
September 14, 2015 - Would a Texas Mountain Laurel thrive in a 4'x4'x4'x4' brick planter with a drain at the bottom? It will get full sun all day. If not, would a Green Cloud Sage or a Waxleaf Myrtle work? Thanks!
view the full question and answer

Washingtonia palms need to be skirted?
August 31, 2008 - Dear Mr. Smarty Plants, I have five Washingtonia palms on my property that have never been skirted and look rather shabby. The interesting thing is that they have thrived (20-30 ft) here to begin with...
view the full question and answer

Live oak leaves turning yellow after planting in Houston
December 19, 2011 - We bought a 65 gallon live oak in early October, and have been watering fairly heavily three days a week. It seemed OK, then all of a sudden lots of the leaves are turning yellow. Is it getting too ...
view the full question and answer

Honeybees swarming around galls on oak trees
September 28, 2015 - A large number of honeybees have descended on a live oak tree in my backyard. They appear to be feeding on the numerous galls on the tree as if they were flowers. What's going on?
view the full question and answer

Care of Styphnolobium affine, Eves necklace
October 05, 2007 - I have an 18 yr old Eve's Necklace tree that is dying from the "bottom up". It has only a few leaves at the very top of the tree. I have, connected to the gutter, a rain barrel from which the exc...
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