Agave and Shrubs

[Adam Trujillo]

So I am designing a planting design that has a combination of agave and low water use shrubs.  I know that the agave will benefit from a gravel or d.g. rather than mulch while it seems that the standard for low water use shrubs is to use an organic mulch.  What should I specify in a planter that has both?

Thanks in advance for your input and suggestions!

[Thomas J. Johnson]

d.g. 3/8″ – 1/2″

Or tumbled recycled glass…

What about used ball bearings? Can we find a source for used industrial ball bearings…? I’m not even kidding…

“Awww, come on guys, it’s so simple. Maybe you need a refresher course.
Hey! It’s all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads. And I’m gonna need ’bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.” – Fletch

What about those small terracotta balls… an interesting cross between d.g. and mulch… hmmm….

[Rob Halpern]

Well, you wouldn’t plan a plant combination in one planter where some plants required dry soils and dry crowns while their neighbors required moist soil.. so there is no horticultural reason to consider two mulches (aside from the design aspects). Shrubs do not require organic mulch as such. Depending on the shrubs, they may require a more organic soil than Agave… but again, that makes them bad companions for agave.
Match your plants to the conditions and the mulch to the plant needs and aesthetic.

[Adam Trujillo]

So Rob, are you saying that the drought tolerant shrubs shouldn’t be planted along with agaves or just don’t use mulch? The agaves are going to be planted at the high point of the planter so drainage is moving away from them.

Both plants are low water use and the mulch will help prevent moisture loss for all the shrubs while also preventing weed growth so I don’t think want to eliminate the mulch for the sake of the agaves…. However, I understand that agaves don’t do well with organic mulch/soil at their crown.

So I’m thinking since the plants will be planted in rows to have a bender board separate the d.g. and the mulch. That way both plants have ideal growing conditions?

[Rob Halpern]

The mulch (any mulch) serves to retain water, keep down weeds, and visually tie the planting together. With some plants, an organic mulch can hasten stem or crown rots… so ill advised for agaves, etc.
Use the stone/marble/recylced glass/glass eyeball/ball bearing/whatever inorganic mulch of your choice on agave and shrubs alike. Keep in mind that inorganic mulches may get hot in hot sun, so your shrubs must be OK with that, like the agave is. Make sure the planter drains well and the soil mix does too. As long as your “drought tolerant shrubs” (that can mean many things) have the same requirements for soil type, soil temperature, and moisture as the agave.
Good luck Adam!

[Thomas J. Johnson]

Adam, you have your degree in Landscape Architecture, with 1-4 years experience and are currently employed!? The world is not fair, indeed…

You need to choose shrubs that require the same conditions as agave and use an appropriate mulch / ground cover. Hint: It’s not 3-4″ of cedar chips…

I think I’ll just go get my HVAC license now….

[Adam Trujillo]

That’s because I’m cheap labor ; )

Don’t give up yet, our office seems to be picking up in the past couple weeks. I think things are s l o w l y starting to move again.

Good luck and thanks for the info!

[Yekaterina Yushmanova]

Yes, you definitely should use non-organic mulch around agave. Decomposed granite, glass, rock, etc. It should be totally fine to use same materials around the shrubs. What kind of shrubs are you using exactly and what is the geographic location? A lot will depend on how much rain and heat the plants will be getting.

[Boilerplater]

Agave, like most desert plants, are indigenous to soils that have very low levels of organic matter. They tend to prefer it that way in cultivation. In my experience, agaves in platers can be affected by heating of the soil, particularly if it has a southern exposure. Of course it get much hotter in Las Vegas, where I am, than Thousand Oaks. Here we typically use rock mulches as organic mulches get blown away and disintegrate quickly in the dry climate. As has been noted, reflected light from rock can burn the underside of leaves on some shrubs.
Using two mulches would be a waste and not likely to be kept that way over time. That is, when it is time to add mulch, one type will be used.

[Adam Trujillo]

There will be rows of Lomandra longifolia ‘Breeze’ and Dianella revoluta on both sides of the Agave. Its in Southern California, Sunset Zone #18. They will be getting full sun, which is why I was concerned about using the d.g. around them since I didn’t want them to burn up in the valley heat….

[Adam Trujillo]

Yeah, you make a good point about maintenance later down the road. Didn’t realize combining agaves would turn out to be so difficult when it came to deciding on a mulch….

[Yekaterina Yushmanova]

They are both Australian natives and adapted to a wide range conditions, but I’m not familiar with them enough to advise on their preferred growing conditions. As mentioned above you really need to match the water needs closely, otherwise there will always be a problem. You could also look into different kind of agave as some of them can take more water and organic matter than others.
If you use a light colored non-organic mulch it should keep the surface cool enough (will depend on the microclimate of course). I would also consider plant maintenance, trying to prune or trim around agaves can be a pain.

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