and now …..

No longer an empty space. I decided to move the young Yucca faxoniana because there’s already one in the front yard, and two might seem like a Statement.

Note my complete lack of shame in taking pictures with the Coolpix in the blindingly bright Denver sun and posting them.

The formerly prostrate opuntia is now woozily adjusting to life as an upright plant, and I added an Agave palmeri in back, because, like any truly sophisticated gardener, I happened to have an extra one.

You may think I haven’t studied feng shui (you’d be right), and that four of something is wrong, since it’s supposed to be an odd number, which four is not. (That much I know.) But there is, in fact, a fifth agave, Agave parryi var. huachucensis, off to the left. (There were two more of these but they rotted after being smothered by rabbitbrush leaves in winter.)

The stump of the rabbitbrush is still there, of course. I must have my gardening staff dispose of it.

The choice of Agave parryi was easy. I already have a flock of A. havardiana

and, even though there are about forty plants of parryi in the back yard, pupping like crazy, I wanted the “Salman No. 2” especially, and they were on sale.

The most important factor in this decision (really an impulse, but “decision” makes it sound like thought went into this) is that this species will tolerate being covered with snow for weeks on end. Some won’t.

Since I have nothing to do in the winter except think about things, I wondered why certain agaves were cold hardy and others were not. The habitats of the hardy agaves are not especially cold, even by Denver standards (which is not as cold a place as people make it out to be, though it can certainly get cold, occasionally); the Agave havardianas come from the mountains of west Texas, which are not much higher than the nearby town of Alpine. The record cold temperature there is 17 above.

So I sent an email to Wendy Hodgson, the agave expert at Desert Botanical Garden in Phoenix, to see if she had any insight. Well, of course, people in Phoenix don’t concern themselves much with winter hardiness, but she did direct me to two books by Park Nobel, both of which I acquired, and sort of read.

The gist of it seems to be this. Agaves do not go fully dormant in winter. Cold hardening takes place within a few days of exposure to cold, but the roots are still capable of pulling moisture into the leaves. (In fully dormant plants, this doesn’t occur.)

Dry soil blocks the root hydraulic conductivity (Nobel’s term), preventing the solutes (the “antifreeze”) in the leaves from becoming diluted. If the roots are able to pull moisture into the plant, and subfreezing temperatures follow, the result is that the plant, to use a technical term, is mush.

The second critical factor is hardiness of the leaf cuticle. Some species are able to tolerate cold if they’re in bone dry soil, but the leaf cuticle is unable to repel this constant assault against it, with the result of yellow or white dry spots, usually at the tips of the leaves. Continual cover of wet snow, thawing during the day, freezing at night, will cause increasing spotting of the leaves, to the point where they eventually just dry up.

What all this means for a person like me, who needs more species of agaves and refuses to acknowledge that there’s no room for them in the garden, is that I have to design some sort of protective covering, a roof or cloche or something, to keep snow off the ones I would like to try. (Examples, Agave parrasana, A. montana, A. macroculmis.) Or just buy a snow thrower and then it’ll never snow again.

Anyway, that’s the story, briefly. I’m probably the only person in the world who cares. Typical.

While I was taking pictures, I noticed a creature who cares nothing about agave hardiness, or anything else that humans worry about. I should take a cue from this.

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6 Responses to and now …..

  1. Lucie says:

    Don’t tell me you took this one with your Coolpix, Bob. Charming! So glad you put forth in writing your agave knowledge…I could hardly absorb your brainy explanation when I met you at your place last month.

  2. Susan ITPH says:

    Glad you posted this, as it’s been very much on my mind as I’m nursing a few Salmon no.1s and a neomexicana along in pots under cover here in Utah. The norm is always some snow cover, so I’m trying to devise some strategies myself. Old clear plastic playground domes as giant cloches are my favorite fantasy solution.

    • paridevita says:

      Snow cover is okay for agaves, so long as the air is cold, because then the snow is dry. What they really don’t like is snow that thaws during the day and then freezes at night, over and over again. The leaf cuticle has a hard time enduring this.
      Sun on the plants warms them up faster than the surrounding snow, which aggravates the problem. Bottom line, very cold, with snow, good; not so cold, with snow, not so good. The plants want to be bone dry around the crown and roots.


      • Susan ITPH says:

        We tend to land on the not-so-cold with snow side of things. All one can do is plant on a sandy slope and pray, hence my cloching fantasies.

      • paridevita says:

        Making sure they don’t take up water when it gets cold is the critical thing. It varies widely with species, and maybe provenance, so you have to experiment. A. utahensis seems to be the hardiest….though I rarely like to talk about hardiness until after winter is over.
        I thought about cloches too. Something opaque, that I could put over them (I’d need about 50), that weighed 300 pounds so the winter winds wouldn’t be able to lift them up and send them to Kansas.

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