Austin Heritage Tree Foundation
Protecting trees

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The Austin Heritage Tree Foundation's mission is to protect all heritage trees in Austin

"You can plant a thousand seedlings, you can plant a thousand trees,  
                                      but you have to wait a thousand years for a thousand year old tree…
                                                        you can plant a brand new forest, new needles and new leaves,
                                                                          but there's nothing like the old ones if you're seeking true releaf”.


01.10.15:  Please help the 20 Zilker heritage trees impacted by the USA Cyclo cross Championship bike race, held under the trees canopies (01.06.15 to 01.11.15).  Details at the Tree 911 Alert page.


We need your help to be able to provide the post care for this tree.  We need to raise an additional $3000 for the first year of post care (water, meter, pest control, soil aeration).  The fund will remain open until we reach that goal.  

The Taco Bell tree, the heritage tree at Oak Hill, was transplanted successfully 4 months ago and the tree is doing great.  The Austin Heritage Tree Foundation (AHTF) is watering it and providing care.  See an impressive video of the move in the Taco Bell Tree  page. 

We have setup a fund at, click on the Austin Heritage Tree Foundation box (6th from the top).  Please, email  with the amount and donor’s name so that we know that your donation was for the Taco Bell tree.  Donations are tax deductible.  See instructions below to donate by mail or phone. 



AHTF has setup an Austin Heritage Tree Foundation-Taco Bell tree fund at the Austin Parks Foundation.  Donations are tax deductible. 

Please, contact Michael Fossum, AHTF (
) with any questions regarding the tree or the fund.

  • Send a check to the Austin Parks Foundation .  Please, make sure to write “Austin Heritage Tree Foundation- Taco Bell Tree” on the memo line.  Please, email with the name of donor and donation amount so that we can confirm your donation.
  • Call the Austin Parks Foundation at ext. 1 to donate by phone.  Make sure to specify that your donation is for the  “Austin Heritage Tree Foundation- Taco Bell Tree.”  Please, email  with the name of donor and donation amount so that we can confirm your donation.  Please, contact Michael Fossum, AHTF, with any questions regarding the tree or the fund.    

Make sure to click on the Austin Heritage Tree Foundation box (6th from the top).  Please, email  with the amount and donor’s name so that we know that the donation was for the Taco Bell tree. 


If a healthy tree is about to be removed and has a diameter of 19 inches or larger, explain to the person about to cut the tree that he/she needs a permit from the City to remove a protected tree and ask them to stop.  If you can't talk to the person, call 911 and ask for the Police Department.  Explain that a tree protected by the City of Austin is about to be removed, and that the tree removal may be violating the City's Protected Tree Ordinance 25-8-261 or the Heritage Tree Ordinance 25-8-641.  Ask them to send a patrol car right away. 

In addition, contact the City Arborist Office by emailing
(emails are read even on weekends), but be aware that it takes time to get a reply.  If there is an imminent removal, don't wait and call the police to prevent the tree removal.  If there is time and you can't email, call 311 and report the potential tree removal.  Give them a sense of urgency, otherwise it may take time to get a reply. 

More instructions at the City Arborist web site:
and in the "
Imminent Tree Removal" page .

Mother Pecan, pictured below, became a legend in October 2011 by winning the City of Austin's Tree Of The Year 2011 Award!  Watch Thom Woodruff reading Susan Bright's poem "Legend" in the "Arbor Day TOY" page.  Susan wrote this poem for Mother Pecan and all of the heritage trees at Barton Springs Pool. 

Help save trees!
  Come mulch and water heritage trees to help them survive the drought.  Look for our latest opportunities in the "Mulching Events" and "Volunteers Needed" pages.

Help save trees by joining our foundation!  We protect and advocate for heritage trees, educate the public about heritage tree issues and tree care, and volunteer to make a difference. 

Email Michael at  if you are interested in joining and helping us.

We can speak about various tree care and tree ordinances at your school or association.  We can show you how to water heritage trees.  We don't have to loose all our trees due to the drought.  Let us show you what to do.


Click here for Don Gardner's Watering Guidelines for Trees

Established native trees don’t often require supplemental watering, except under drought conditions.  Established trees need to be watered slowly and deeply, for about 90-120 minutes (depending on size), every 3 weeks (every 2 weeks when above 90 F).  This year, we may need to water 4 weeks from the last rain until the end of September, perhaps longer, depending on the drought.  Young trees, from one to three years old, need to be watered twice weekly for about 10 minutes (once weekly when it's cooler) for the first three years to get established.

It is imperative that we water our trees.  Austin is facing an exceptionally bad time of high heat and drought that is killing hundreds of trees.  Our trees have been in trouble for several years now.  We are essentially in a four year drought, and we are now losing drought-tolerant, established and healthy native trees all over our area.  We must help trees survive this drought.

Trees are important:  It is critical to help our trees because they provide significant ecosystem benefits.  A large shade tree can reduce energy usage equating to 30% lower AC bills.  Trees can increase the resale value of your property by up to 20%.  Trees, even if stressed, can be saved with additional watering.  The lack of water weakens and stresses trees, making them more susceptible to get diseases and insects, and even die.

It is expensive to allow a tree to die in your property.  If a tree dies on your property, you will have to remove it because it will be a safety issue.  The removal of a large tree can cost $1,000 or more.  The cost of watering the tree from now until September is negligible in comparison.  Trees grow very slowly, so they are not easy to replace.  It’s not as easy as replacing dead plants in your landscape.   

Trees must be watered following City of Austin’s water conservation guidelines.  These guidelines are not meant to prevent watering your trees, but, instead are intended to water trees in an efficient manner, providing them just the right amount of water they need, during the right time of the day, to prevent run-off and wasting water. 

City of Austin Water Conservation Guidelines are currently at Stage 2:



You can water with an automated irrigation system from midnight to 5 am and from 7 pm to midnight, or with hose-end sprinklers from midnight to 10 am and from 7 pm to midnight one assigned day of the week.  You can water anytime by holding the hose by hand, with drip irrigation, with automatic tree bubblers, or with a refillable watering vessel, such as a bucket or a Treegator®. 
You can also water trees (and vegetable gardens) anytime with soaker hoses placed under the tree canopy.  For trees 16 inches in diameter or larger, several drip irrigation or soaker hoses need to be connected together and laid down on a spiral pattern to provide water to the outer half of the dripline.  A single drip irrigation or soaker hose will not provide enough water to a larger tree, especially if the single soaker hose is laid close to the trunk. 

Only fountains with either a fall or spray of water greater than four inches are prohibited, unless necessary to preserve aquatic life.  It's OK to put water in the birdbath or water dishes for wildlife.  Critters and birds also need our help to provide them with a few small water sources during the drought, but change the water frequently.

                                                     HOW TO WATER TREES

Don’t water the tree trunk, water away from the trunk, from ½ to the edge of the dripline (the outer half of the dripline).

Typically, the roots of a tree extend to the dripline (and often beyond), and many of the important feeder roots run in the top 12 inches of soil.  The dripline is, more or less, the area under the canopy (
click here to see drawing). 

The roots need to receive water applied as evenly as possible to the outer section of the dripline because this is where the water will be most beneficial to the roots.  The most active feeder roots are located in this outer section.  It is ineffective to water the tree trunk, and this will eventually lead to fungus and decay at the base of the trunk, which will kill the tree

                                                 METHODS TO WATER TREES

There are various ways to water trees.  Choose the one that is best for your situation and location.  Don’t allow water to run-off, and check that enough water was provided to the tree. 


Test to check that sufficient water is provided to tree, more or less evenly to the outer half of the dripline:  

Move away the mulch or other material above the soil, and insert a hand trowel at the dripline, about 3-5 inches deep, to confirm that the soil is wet to that depth.  If not, water for another 30 or 60 minutes.  Check that the soil is wet at a couple of spots in the outer dripline to make sure that the water was applied more or less evenly.  Be careful to not damage tree roots while making the small holes.

A couple of days after watering, look up at the tree canopy and check that the tree looks OK.  If tree looks droopy and thirsty, you may need to water longer, or try a different watering method.

1)  Drip irrigation:  This is the most efficient method, and can be easily installed by the homeowner with kits that are somewhat affordable and can be automated (with a hose timer).  The kits consist of a small plastic tube that you lay on the ground, and connect to your faucet.

Place tube on the outer half of the dripline, around halfway between the trunk and the edge of the dripline, install on a spiral pattern for better coverage, place emitters to water as much of dripline as possible, as evenly as possible.  Cover tube with a thin layer of mulch. 

2)  Hose on the ground:  This is the simplest method and requires no further investment, but it requires you to change the hose to 4 locations around the tree, to be able to provide water evenly to the outer dripline section. 

Simply place the end of the hose, at a low water flow rate, on the ground.  Place hose end underneath mulch or any other material above ground so that the water goes into the soil.  Water for the amount of time described below.  Move hose to another spot.  Repeat.  Since this process takes a bit more time and effort to water, remember that you can continue watering the spots that you missed later in the week. 

Optional:  Metal or plastic bubblers are available for less than $10 to connect at the end of the hose, so that the water is more spread out.

3)  Soaker hoses:  This is a very simple method, but the amount of water delivered may be more localized than the other watering methods, depending on your soil type.  To cover the area in the outer half of the dripline, install the soaker hose in a spiral pattern (click here to see drawing), away from the trunk.  Place the soaker hoses 0.5 ft apart for sandy soils and 1.5 ft. apart for clay soils.  You may need several soaker hoses connected together.  This method may require watering times longer than indicated below.    

4)  Sprinkler on the dripline:  This method allows some water to be lost due to evaporation into the air, but it's the best method to water the outer half of the dripline evenly, which is important for the roots.  This is also a good method to water trees if you have many trees and/or you can’t move hoses around.  Use an oscillating sprinkler (the kind that goes right and left, not the kind that projects water far away in a circular pattern), or a small ring sprinkler for smaller trees.  These types of sprinklers emit larger water drops which reduces evaporation losses.  Avoid sprinklers that emit mist (to reduce evaporation losses) and avoid using any sprinkler when it's windy.

Place sprinkler around ¾ of the way out from the trunk towards the dripline, and water half of the tree (click here to see drawing), move sprinkler to other side of the tree, repeat.  Avoid watering the trunk.  Don’t try watering the entire tree at once by placing the sprinkler close to trunk.  There will be a large shadow area behind the trunk that won’t get any water. 

Note:  Don’t use pipes or wands stuck into the soil 12-24 inches deep because that is not where the tree roots are.  Watering deeper than the top 12 inches will miss the active roots, wasting water.

                                               HOW LONG TO WATER TREES

At temperatures higher than 90 F, you may have to water established trees every 2 weeks.  When it's cooler than that, you may need to water established trees only every 3 weeks.  You will probably need to water longer the first time after a long dry period.

Watering time depends on the size of the tree, soil type and site conditions, and will vary depending on the method you choose to water and the water flow rate used.  The idea is to provide 1 inch of water slowly to the roots of established trees.  Water the tree deeply by watering at the slowest flow rate possible to allow it to penetrate the soil 3-5 inches deep.  In general, follow the recommendations below, but check that sufficient water was applied to the soil (with a hand trowel to a depth of 3-5 inches), and if not, continue watering slowly.  Figure out what works for your situation.  Mulch will absorb some of the water, so you may need to water longer where you have mulch, if you are applying the water on the mulch. 

Avoid light frequent watering because this encourages shallow rooting which will damage the tree.  It’s very important to water with a slow water flow rate on slopes, compacted soils, and heavy clay soils to prevent run-off.  Soaker hoses are best for those situations.  A tree surrounded by sidewalks and asphalt will need more water.

1)  Young trees, water once or twice weekly:  Trees 1 to 3 years old need 10 minutes of watering.  The younger the tree, the more frequently it will need to be watered.

2)  Established trees, water every 2-3 weeks:

a)  Trees up to 15 inches of trunk diameter need 5 gallons of water per inch of trunk.  This is about 30 minutes when using a hose end at low water flow rate.

b)  Trees larger than this need 10-15 gallons of water per inch of trunk.  This is about 90-120 minutes when using a hose end at low water flow rate.
Exceptionally large heritage trees need 3-4 hrs. when using a hose end at low water flow rate.

                                                     WHAT ELSE CAN BE DONE    

Ø    Improve your soil with organic compost and cover with mulch: 

Clay soils retain water, be careful to not overwater.  Sandy soils can drain too much.  Adding 0.5 -1 inch of composted organic material and 2-3 inches of organic mulch on the soil surface can help hold and prevent water run-off.

Apply 2-3 inches of mulch, from 3 inches away from the trunk to the edge of the dripline.  Don’t apply mulch thicker than 3 inches because this makes it harder for water and nutrients to reach the roots.  Trees with large canopies shade the grass and plants under the canopy, so instead of fighting to grow anything there, apply mulch to benefit the tree.  Grass and plants under the tree canopy compete for nutrients and water with the tree roots, so try to mulch as much of the dripline as you are willing to give up.  Any kind of organic mulch will do, but shredded hardwood mulch is preferred.  In addition to preventing evaporation, mulch will decompose and work itself into the soil, enriching it and helping the tree roots.  Mulch needs to be re-applied every 1-2 years. 

Small rocks, gravel, glass and other “mineral mulches” are not good for trees because they don’t provide nutrients to the roots and heat up the area.  In addition, they will need to be removed to apply mulch.  These non-organic mulches are OK to provide drainage around cactuses and succulents, but please, don’t use these near the trunks and on the driplines of trees.

 Ø    Plant drought-tolerant native trees.  Plant large and long lived shade trees.

Ø    Fix all leaks to avoid wasting water, check your hoses and connectors, and use a hose timer to shut off the hose if you forget.

Ø    If using recycled water, make sure that it doesn’t have soaps, chemicals, or too much salt because these will affect the tree.  Some soap types are OK, but some are not.

Ø    To promote root growth water twice as long during non-drought years.


Michael E. Fossum
Executive Director
Austin Heritage Tree Foundation

Austin, Texas

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