Sunday, January 18, 2015

Cold tolerance of agaves

Yesterday’s post, ASDM: Agaves in the snow, prompted me to do a little bit of research into the cold tolerance of agaves. There’s a wealth of information available online and in books, but much of it is in bits and pieces. I attempted to compile a list that is as complete—and hence as useful—as possible. The tab “Sources” in the spreadsheet below lists the sources I relied on most; where they disagreed with regard to the cold hardiness of a given species or cultivar, I picked the mean value and rounded it up.

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Agave ovatifolia, the whale’s tongue agave, is one of the best choices for cold and wet winters

My hope is that this list will be a useful reference for your own trials. Please bear in mind that cold hardiness depends on more than just temperature. For the majority of agave species, the most crucial factor aside from the absolute air temperature is how wet or dry the soil is when a cold spell hits. Completely dry soil allows agaves to withstand colder temperatures than they would be able to tolerate if the soil is wet. The worst-case scenario would be a deep freeze following rain, especially if the soil is heavy and has poor drainage.

You can give your agaves the best chance at winter survival if you plant them in loose, well-draining soil. Many gardeners aren’t blessed with such conditions so don’t be frustrated. Agaves have a shallow root system so you only need to amend the soil to a depth of 8-12 inches. Adding coarse inorganic material such as pumice, decomposed granite, chicken grit, or even small rocks or pebbles is a great way to improve your soil. Better yet is to plant agaves (and other succulents) on a slight mound so the rain runs off more quickly; that’s the approach I prefer.

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Agave montana, another good choice for wet-winter climates

Finally, some agaves are able to handle cold, wet winters better than others. Agave montana, Agave ovatifolia, and Agave parryi ‘JC Raulston’ have proven themselves under these conditions.

I would love to know what your own experience is. Which species work well in your climate? Please leave a comment below.

P.S. I’ve added the table below to a page called “Agave Cold Tolerance.” You can access it at any time from the menu bar at the very of top of the page.

 

16 comments:

  1. Fantastic idea Gerhard, and VERY helpful!

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    1. Glad to hear that. I hope having the °C column helps non-Americans.

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  2. Great information Gerhard! I've shared the post with a friend who has had to deal with frost damage to her succulents this winter. I'm lucky in that our temps rarely get into the 30s.

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    1. Kris, I hope your friend will find the info useful. You're so lucky to live in a climate where it rarely gets into the 30s. We hover around the 34-32°F mark a lot in the winter--too cold for me but fortunately not cold enough to do much damage.

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  3. I highlighted column B, went to data, and clicked on sort A thru Z which gave me an easy way to see which ones are below my cutoff range of 27 degrees. Am pleasantly surprised to see how many I can grow without too much worry. Sue

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    1. Excellent! I'm glad you were able to do that.

      The actual date lives in a Google Docs spreadsheet where I can easily maintain it. This post, and the "Agave Cold Tolerance" page, then get updated automatically.

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  4. Wow ! Great info Gerhard. Thanks do much. This is one big question that many of our Succulent Fanatics group ask all the time. Sharing.

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    1. Laura, thank you for sharing. I'm hoping that with public input we can make this list even better. If needed, I will add a comments/notes column.

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  5. You rock! I've been trying to get through to read this post since I saw it on FB yesterday but I was having that issue again where I can't get through and it looks like your blog is down. Oddly I was also having the same issue with Mark and Gaz's this time.

    Anyway this is fabulous! I agree completely with your saying that Agave montana, Agave ovatifolia, and Agave parryi ‘JC Raulston’ are best suited able to handle cold, wet winters. Unfortunately I lost my A. monanta due to it remaining covered longer than it should have (years ago, when I was injured). Agave bracteosa is another that seems to fare well under those conditions.

    (I would also add that size at planting is an issue. That A. montanta was a good gallon size, where as I've planted smaller ones over the years that just haven't been able to get established)

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    1. Loree, I agree with everything you said. The larger the plant when you put it in the ground, the better its chances of surviving its first winter. The time of planting matters too. With agaves, I found that planting them in early summer (May here in Davis) helps them hit the ground running and get established before their first winter.

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  6. Thank you for the useful information and making it easy to access in the future. Here in Houston when clients want agave we often put them in a raised bed made with ledge stone and filled with a sandy soil. It seems to work well. I love your photos too!

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    1. I'm convinced that planting agaves in a raised bed or on a raised mound is the best thing you can do to help them survive wet winters because excess water drains away from their shallow roots.

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  7. Thank you so much for doing all of this work. I am planning on planting my first agaves outdoors this (late) spring and have been fussing and fretting over the best options for Portland. This confirms and expands on the choices I was already leaning towards. You're a star!

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    1. Hey, you're making me blush! Loree's blog (dangergarden.blogspot.com) is a great resource for agaves in Portland. Also see her comment above.

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