Mesquite Beans and Palo Verde Pods in Tucson Artificial Turf

A tan bean in the pile is last summer's mesquite crop. It did not fall this week. The University of Arizona Cooperative Extension publication Mesquite and Palo Verde Trees for the Urban Landscape says velvet mesquite flowers in spring, and the tan seed pods ripen in mid to late summer. By early November those pods are on the gravel, under the patio chairs, and worked into the infill of any lawn that sits under the canopy.

That shows up first in Tanque Verde, where mature velvet mesquite leans over the turf, and under the hybrid mesquites of the Catalina Foothills. Artificial turf cleaning in the Catalina Foothills often starts with beans and tiny leaflets at the backing, not with dust alone. Oro Valley and Casas Adobes get the same mat wherever a palo verde was planted at the edge of the lawn.

The National Weather Service 1991–2020 normals for Tucson put November's average high at 75.1°F, the average low at 47.9°F, and the rainfall normal at 0.56 inches. That rain will not flush a bean through the backing. It is enough to soften a pod that has been sitting in the sand since August.

1. Three Kinds of Litter, and Only One Blows Off

Part the blades under the drip line.

• Whole pods sit on top or wedge sideways between blades. A velvet mesquite pod is a long tan bean. A blue palo verde pod is flatter and shorter. Both are large enough to pick up.
• Broken pod pieces and the seeds inside them drop into the infill. Foot traffic cracks a dry pod, and the fragments disappear under the blade tips.
• Leaflets are the fine litter. Mesquite and palo verde leaves are bipinnate, a feather of tiny leaflets. Once those leaflets leave the stem, they sift to the backing like dust.

A leaf blower clears whole pods and loose leaflets that are still on the surface. It does not lift a bean that shoes have pressed into the sand. Desert broom fluff is a different seed and a different problem. That one is in our fall and winter turf care guide.

2. Palo Verde Pods Are the Litter the Extension Names

The same landscape publication is direct about palo verde. The pods can create heavy litter. Under a blue palo verde, the profuse flowers and seed pods can create heavy litter under the canopy. Foothill palo verde seed pods can create heavy litter too. Short thorns on the twigs are a problem near walkways.

On open gravel that litter stays visible. Artificial turf combs it out of sight. A pod that landed in July is a flat brown chip by November, packed at the base of the pile along the path from the gate to the patio.

Twigs matter as much as pods. A short palo verde thorn on a fallen twig does not dissolve. It can sit point-up in the infill where people walk barefoot. Pick twigs out by hand. Do not grind them in with a broom.

Newer yards in Oro Valley often put a palo verde at the corner of the turf for shade and for the yellow bloom. The litter lands on the lawn. Turf maintenance in Oro Valley along that canopy line is pods, thorns, and the fine leaflets that follow a dry spell.

3. Beans on the Ground Are Not a Harvest

Mesquite pods are a traditional food when they are taken ripe from the tree. The University of Arizona Cooperative Extension publication Mesquite: It's Food says Arizona pods generally ripen from June into late July, and that the best pick is from the tree before the monsoon is fully underway. The publication also states that aflatoxin-contaminated products are a health concern for people and animals, and that pods in contact with the soil are more likely to be contaminated.

A pod that has spent the summer in turf infill is a ground pod. Leave it out of the kitchen, and do not leave it where a dog can chew it because the pod still smells sweet. Pick the beans up. Bag them. Do not stack them on the gravel the dog crosses on the way to the gate.

4. Leaflets Come Later, and They Pin the Blades

Velvet mesquite leaflets turn light green or tan and fall after the first hard freeze, in late fall or early winter. Tucson's November normal low is 47.9°F, so early November in the valley is often still ahead of that drop. The beans are the litter that is already here. The leaflets are the layer that lands on top of them.

Pods plus leaflets plus foot traffic is how a canopy line goes flat. You see the side of each ribbon, and the lawn looks shiny from the patio. Brushing the tips does not lift blades that are pinned by a felt of leaflets. That is the same matting described in our guide to flattened artificial turf, with tree litter as the weight.

Foothill palo verde holds its tiny leaves only for a short time after moisture, even in natural desert. Those leaflets are already in shaded turf by November. They are too small to pick out one by one.

5. Clear the Pods While They Are Still Whole

Work while the lawn is dry, before anyone walks it.

• Pick whole pods and twigs by hand, starting at the gate path and the first few feet under the canopy. Wear a glove. A pod often lands with a thorny twig.
• Blow leaflets outward, toward the gravel, with the blower on low and the nozzle across the pile. Do not blow them into the corner where the dog lies.
• Then part the blades. If brown chips and a felt of leaflets are still at the backing, the blower is finished. The rest is in the infill.
• Turn drip emitters back into the gravel. An emitter aimed at the turf softens pods and sticks leaflets to the sand.

Power brooming and extraction take that buried fraction out. An artificial turf cleaning opens the sand, pulls pod fragments and leaflets out, and stands the blades back up along the canopy line. A yard under several mature trees stays ahead of the next summer crop on a maintenance plan. If the beans have been left since July, request a quote and say the turf sits under mesquite or palo verde.

What Not to Do

• Do not hose the pods. A soaking drives cracked beans into the drainage holes, and the beans do not dissolve. November's normal rainfall is only 0.56 inches. A hose puts down more than that and leaves the litter in place.
• Do not use a metal rake. The teeth catch the tuft and flick pod splinters deeper.
• Do not run a string trimmer along the canopy line. There is nothing to mow. The line frays the blades and shatters pods into the infill.
• Do not grind ground pods into flour. The extension note on aflatoxin is about pods that have been in contact with the soil.
• Do not wait for a winter rain to wash the lawn. The rain is light, and a packed pod layer is what makes the next shower sit on top of the turf.

Pick the beans up while they are still whole. Blow the leaflets while they are dry. If the canopy line in Tanque Verde, the Foothills, or Oro Valley already feels crusty underfoot, that litter has to be extracted. Call 520-248-3478.