About a Rock: Mass and Void

“We even have a feeling about a rock, about anything.” – Donald Judd


No, not even for a difficult or evasive interviewee such as Judd

Like function, landscape design is much about the relationship between mass and void. Below are views of the same median I designed for vehicular speeds, though to a degree it also works for pedestrians and cyclists.

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The plants are grown in, showing the relationships between boulders, plants, and gravel mulch. The boulders and plants are mass (positive space). The gaps using mulch are called voids. (negative space) 

Together in a landscape, that’s considered legibility.

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The relationship of mass and void begins with the designer and their plan. Moving plants on a plan is easier than in the field. 

Years earlier, young 5 gallon plants were placed by the contractor helped by the owner’s representative 3 or 4 feet away from boulders per plan, further apart than above. That enabled those plants to grow properly in relation to each other and the boulders.

More than not, project owners and contractors don’t get that. Plants that appear on the plan against a boulder are placed too close, ignoring the plan’s scale and growth. 


Nature often inspires good placement. Even if no person placed all this.

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That’s in Picacho Arroyo, near the above streetscape. Remember the Donald Judd quote?

Also, was Judd being too controlling wanting his works to be installed specifically for their space, or even to create spaces for his works?

Onto another streetscape vignette in the same development…

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There are plant and boulder masses with crushed gravel voids, like the other median.

But with differently-shaped boulders that couldn’t be predicted months earlier on a plan, the contractor and owner did a good job of retaining the plans’ spirit and spacing between once-younger and smaller plants and boulders. Both parties also set the boulders to look real yet be deliberate.

Everything matured graciously.

So, I agree with Donald Judd: a rock…anything!

The Drive: Exit into Tucson

I’ve admired many landscape designs along the freeways and arterial streets in Arizona’s two largest cities for decades.

A critical mass in their horticultural community gets sense, place, and designing for traffic speeds. Photos from 12/22/19:

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This is the first time I exited onto West St. Mary’s Road. Always informative and fun, colleague and friend Scott Calhoun suggested meeting at a parked food truck for lunch.

Since I arrived early and Scott was riding from afar, I had extra time. Burger King was good for a free parking space, so I walked the rest of the way.

ADOT designed some attractive concrete accents at the bridges.

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There’s no shortage of cyclists in Tucson. One cyclist on a mountain bike…

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Desert Willow / Chilopsis linearis above a mass of Beargrass / Nolina microcarpa makes a pleasing vignette while waiting for the light to change. Both are seriously bulletproof species in a wide part of the southwest.

And the other cyclist on a road bike…

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I’ll work back to how I exited I-10. Room for plants to mature.

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Regarding a request to see more Las Cruces pics on my blog, which I’ve shown many, I replied, “I have more to post on Arizona because there is more good arid-region design and plantsmanship in a few blocks of Tucson or Phoenix than in a mile of Las Cruces and El Paso or 2-3 miles of Albuquerque.”

These huge, almost trailing gray shrubs are…Texas Ranger / Leucophyllum spp. During the monsoon season, I’m sure many locals or visitors are very impressed.

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They are spaced well for rhythm, as are their masses for structure. No need to design 3 times as many plants for immediate effect, only to later remove half or more. Or shear into muffins, cylinders, boxes, …

Occasional accents were tucked in, but one must be stopped to appreciate them. Or rolling the dice by walking along the right shoulder, protected only by a curb.

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A minor detail, but some different massing of plants away from the yuccas, then placement of the occasional yucca further from those masses, especially from the drivers’ direction, would have shown off the planting better.

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A few Texas Olive / Cordia boissierii were used, but those were off to the right side and not too visible.

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It’s time to walk back, to join my cyclist / plant nerd friend for some lonche.

This ocotillo had a hard night, yet it’s still trying to hang on by blooming.

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Now, I’m stumped…

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The color combos work, but I’m stumped at the tallish Dasylirion mass in front of the interesting design motif at the corner.

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The plants appear to protect the artistry from taggers, yet they block a large portion of it from view.

I’m standing taking this, so that’s not far off the height of a typical pickup truck or SUV driver. Though perhaps the art is more visible from a Bubba Truck height?

No matter it’s still very appealing.


An inlet shows where passive water harvesting was employed, to allow storm water from the street to soak into the median plantings.

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Both of us showed up for lunch for one of the best tortas I’ve had. And we’re wearing short sleeves in late December!

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Grape Kool-aid

As a high school sophomore, my parents drove us from our Denver home to Carlsbad Caverns via Santa Fe and Albuquerque, for spring break at the end of March 1982.

The afternoon we drove back, I still remember the scent through open car windows on that sunny, warm day. Grape Kool-aid!

Flash forward to March 25, a gray-leaved selection of the plant we saw, Silver Sierra Mountain Laurel / Dermatophyllum secundiflorum ‘Silver Sierra’, is on a project I designed near my present home.

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Near that multi-stemmed, dwarf tree, I used boulders from the Hueco Mountains on the other side of El Paso plus native and cultural companions Beargrass / Nolina greenei and cultural near-native companions Blue Sotol / Dasylirion wheeleri.

The scent at the right moment was strong, even in our thin, gusty, and dry air.

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To think seeing that plant on Walnut Canyon Drive at Carlsbad Caverns Nat’l Park symbolized my downhill slide future career, including this project.

Though on that spring break trip, I was far from knowing the plant’s name with those scented flower clusters or “Chihuahuan Desert”.

We’re now looking north and downhill along the main street into the same development. More ‘Silver Sierra’ mountain laurels are on the right parkway strip.PH-Anthem Stscp1_2020-03-25-SMLPH-Anthem Stscp2b_2020-03-25-SMLPH-Anthem Stscp2a_2020-03-25-SMLPH-Anthem Stscp2c_2020-03-25-SML


The last location at the same project my design used them is another median or island, also with some stunning views.

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A repeat from years ago: remove the stakes from all your mountain laurels. They are unnecessary a year after installation and detract from each plant.

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I wonder what was once growing in the empty soil area that is no longer there? Still no time to locate the original plans.

All this project’s ‘Silver Sierra’ Mountain Laurel were installed from 24 inch box sizes, and they grow slowly at about 6 inches / year.

That dwarf tree is evergreen and prefers alkaline soils that drain decently, or even excessively as on this project site. They are winter hardy to the cooler edges of USDA z 8a (probably thermal belt locations of ABQ, maybe even Roswell NM), and summer hardy to at least the burning low desert known as the Sonoran Desert.


4/11/20 weather:
71F / 41F / 0 or 22c / 5c / 0