Mesquite FAQ’s

We have patterned the GrowPHX Mesquite Mill and & Education Program after the Desert Harvesters’s mesquite milling program in Tucson, Arizona.  Summer of 2019 was our first year doing our own program so the process is bound to improve, however we had a great example to start with because of the encouragement and assistance they shared.  We extend our immense gratitude to our Tucson neighbors for their support and willingness to help!

Here are answers to some Frequently Asked Questions for mesquite harvesting and milling.


  • Who can mill their beans?
    Anyone who is willing to come to our milling events.  We are promoting this as a Phoenix resource, so that means 1.6 million people have the opportunity to bring beans.  However, we only expect a few hundred at the most.
  • Who runs this program?
    This is an education and resource program run by GrowPHX.  A team of two people are managing the program: Janis and Greg, with the invaluable support of Don Titmus, Peggy Sue Sorensen and Brad Lancaster .
  • Who can volunteer?
    Anyone can volunteer! We will set up a sign up site to help with the milling day activities.  Email for info and link to sign up. Other volunteering will be managed as needed.


  • What type of beans can we bring?
    Mesquite beans are the primary focus. We recommend sticking to Velvet and Honey Mesquite for the best flavors. Carob beans will be an option at the end of the milling days because they are stickier and require additional cleaning for the mill.
  • What is minimum amount we can mill?
    We suggest a 5 gallon bucket of dried beans as that will provide approximately 5 pounds of flour. This will vary based on the beans and how packed the bucket is before milling.
  • What is maximum amount?
    We are starting with an expectation that we will be busy, so a limit of 15 gallons for normal processing is our general rule of thumb at this time. We will process more if time allows, and if we are busy we will ask the larger orders to use our will call service.  If you have more than twenty-five gallons of beans, please work with us as we may need to schedule a special event just for you.
  • What is aflatoxin?
    Aflatoxin  comes from an invisible toxic mold that can grow on the beans that fall to the ground, as well as the beans in the trees after rains. These are naturally occurring mold spores that live in the soil, increase after the rains, and typically causes issues for people with compromised immune systems, as well as children and older adults.  We ask that you not take any chances and only collect from the tree or by using a drop cloth under the tree while you collect.
  • What condition should the beans be in for milling?
    The beans should be dry, free from sticks, leaves and rocks. Remove the stems as much as possible. Please DO NOT break the pods into small pieces as this slows the process down, increase the occasional chaff that passes through the mill, and will not change the price per pound. Any sign of mold will reject the whole lot.
  • What color should the beans be?
    Dry beans usually vary from light tan to deeper red. Pink and brown striations are normal, however, ABSOLUTELY no black spots. Green beans are not ripe for picking and will develop a better taste if left on the tree until they lose their green coloring.


  • Where is the best place to collect beans?
    Mesquite trees are native to our desert so they can be anywhere.  Desert washes, parks, backyards, are all options.  If you find trees that you like the taste, be sure to mark them on a map so you can come back to the same trees next time.
  • Where is the mill going to be?
    Until we get the trailer set up properly and road safe, we will only be setting up the mill at the Urban Farm Nursery Lot.  Click HERE for more info, a map, and a picture of the building.
  • Where can I store my beans until I bring them to the mill?
    Store the beans in a dry location. Do NOT allow them to get wet or exposed to humid air.  A few days in a car can help with the last bit of drying them out after harvesting, or storing them in the garage or on a patio in a closed container will also work.


  • When should we collect our beans?
    Pre-rain! Any dried beans on the trees during a rain will absorb the moisture in the air.  This moisture will be problematic and gum up the mill.
  • When will the mill be available?
    We will open for two days in 2020 – June 26th and 27th.  From 8am to 2pm.  Weather permitting as we will not do any milling if the humidity is too high. We will determine future milling based on need and weather.


  • Why do we taste the beans from each tree before collecting?
    Each tree has it’s own flavor, and trees of the same variety and growing in virtually the same spot can taste differently.  Non native varieties can have a chalky after-taste. Some trees can have a bitter flavor, while others can be extremely sweet.  AND individual taste preferences can determine how much a particular tree is appreciated.
  • Why do we never collect beans from the ground?
    Two almost invisible reasons: First – Desert animals love the mesquite tree for its food source as well as its shade. They travel beneath the branches and frankly are not picky about their hygiene and this can contaminate beans that fall on the ground.
    Second – The soil is a natural breeding ground for the invisible mold that can develop into aflatoxin which can be very dangerous for anyone in less than optimal health or with a compromised immune system. This mold is prevalent throughout the valley but is kept in check by the dry heat. We must avoid spreading this contaminant by avoiding harvesting beans that have fallen on the ground.  Use a tarp or ground cloth under the branches as you harvest to increase your yield.
  • Why do my beans have tiny holes in them?
    While the tree is flowering the tiny bruchid beetle will lay its eggs on the flower. As the flower closes up and turns into a bean, the eggs are trapped inside.  When the bean is dry, the young beetle will drill a hole in the bean pod to escape and fly off – this is why we don’t encourage storing beans in the house. These tiny insects are not disease carriers and pose no health hazards. If they are still in the beans while in storage, they will attempt to leave. If they are still in the beans during a heated drying stage, they will die off. If there are still some in the beans during the milling stage, they will get pounded into the flour and are adding to the protein. This will not affect the safety or the taste of the flour.


  • How do I test a tree for flavor?
    Take a dry bean directly from the tree.  Break it in half and chew gently on the open end taking care not to bite down on the seeds or you can break your teeth. Using your saliva to moisten the bean, allow the taste to stay in your mouth for a little bit, unless a bitter or chalky taste is noticed.  Spit out the rough fiber and seeds.  You should be able to taste the sweetness level, as well as the flavor itself.
  • How do I ensure my beans are dry?
    Letting your beans sit in the buckets in your car for 3-4 days while it sits in the sun is an easy way to dry out the beans.  Other methods include air drying in a dehydrator, using a sun oven, or even your regular oven.  Take care not to allow them to roast (unless you’ve tried roasted beans and like the flavor).
  • How much does milling cost?
    We are collecting $7.50 per finished pound of flour with a $15 minimum.  Flour purchased online can average about $14-20 per pound.
  • How can I pay for the milling?
    We will take cash or credit during the milling events.
  • How can I contribute to the fundraising for this program?
    We still need to raise funds to pay off a couple loans for purchase and repair, as well as the supplies, maintenance, and program management. We appreciate all contributions!  Please go HERE to find out how to donate.
  • How can I get one of the Desert Harvesters Recipe Books?
    We are offering the Desert Harvesters Recipe Book as part of our fundraising program.  A Level 3 contribution of $75 we will in return provide you with the Recipe Book and 3 lbs of mesquite milling for free.
  • How can I watch the webinars that I missed?
    An email with a link to Peggy Sorensen’s webinar can be obtained by registering HERE. She covers some of the reasons we harvest mesquite, some of the methods of harvesting safely, and shares some recipe examples as well, and more.
    An email with a link to Brad Lancaster’s webinar can be obtained by registering HERE. He discusses water harvesting, the mesquite program in Tuscon, benefits of native trees, and much more.