Growing medium for a crevice garden

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Anne Spiegel
Title: Member
Joined: 2010-01-26

Janet, my site gets very dried out by wind, which also makes it considerably colder in the winter.  Eriogonums and astragalus, penstemon, convolvulus and oxytropis usually do well here as a result.

Peden
Title: Member
Joined: 2012-01-04

Janet wrote:

Michael, your tufa garden looks realy nice. It looks like you've gotten the stones very close.

That's one of the big problems with a lot of tufa. It is so roughly outlined that it does not lend itself to use in a crevice garden. My idea to use it was to set it on ground from which moisture would wick up into it. A mix that drains too well foils all of this. Tufa is often used set in a pan of water for this very reason. As for growing dryland plants, the tufa might better be used as root-run material, mostly buried in the construction. The mix I've used is fairly fine textured and moisture retentive and I have noticed that it is getting the unsettling habit of becoming unsettled and settling out of the crevices! Roots will anchor the raised soil in time but we are talking Androsaces here. They don't grow all that fast. A berm may not be all that necessary for technical reasons. As I recall Anne's beds are level though terraced on her ledges. I've personally seen no better example overall of dryland perennial cultivation than she displays, in the east but recall that Mike Slater once showed several fine dry sand beds -no tufa- he had made in Pennsylvania. Mike probably still does that. There's lots to aspire towards! Regarding this all; it might be best to aim at a certain type of micro habitat; alpine; dryland; etc. and mix mix accordingly. The chemistry is also very important; of this I become more and more certain as I dabble on into the unknown.

Michael Peden
Lake Champlain Valley, zone 4b
Four and a half months frost free
Snow cover not guaranteed

Anne Spiegel
Title: Member
Joined: 2010-01-26

Thanks, Michael.  I don't, however, use tufa for drylanders.  The tufa here supports androsace and asperulas, daphnes etc.  The tufa is roughly a crevice garden but because of the irregularities you'd never know it from the surface.  Underneath, they're quite tight together and the irregularities leave small channels for delving roots.  When I've made a planting hole in tufa I frequently have drilled all the way through.  Most of the larger pieces are at least 2/3 buried and underneath it stays reasonably cool and moist.  I'm not able to water plants in the garden and the wind tends to dry things out too quickly for plants to establish in the tiny holes that are often recommended for planting in tufa.  I think if you do that you'd have to keep it misted or watered during periods of drought until well-established?  The great thing about gardening is that there are as many recipes for success as there are gardeners.  You always end up doing what works for you.  When I started rock gardening I tried to grow the traditional alpoine plants I read about.  It quickly morphed into something entirely different called "what does well here."

cohan
cohan's picture
Title: Guest
Joined: 2011-02-03

Great information here, folks! I have no tufa, but it's still interesting to read the technical musings...

west central alberta, canada; just under 1000m; record temps:min -45C/-49F;max 34C/93F; http://picasaweb.google.ca/cactuscactus  http://urbanehillbillycanada.blogspot.com/

Novak
Title: Member
Joined: 2009-10-07

An article by Zdenek Zvolanek has lots of good information on crevice gardening, with the advice that the medium in the crevices can be ordinary loam. It's not what I would have expected, but I can't argue with his success in creating crevice gardens. This is for crevices that are around a half inch wide and near vertical. In my tufa garden, the crevices are bound to be larger and at irregular slopes, so I'll be using a leaner mix, though I haven't yet decided exactly what to use.

The article was originally published in 2003 in the Rock Garden Journal, but it's available for downloaded on the SRGC site (http://www.srgc.net/forum/index.php?topic=4656.msg125155#msg125155).

Janet
Philadelphia, Pennsylvania, zone 7a
Webmaster for the Delaware Valley Chapter (dvcnargs.org)

RickR
Title: Moderator
Joined: 2009-09-21

Baldasarre Mineo give the same advice for very narrow crevices.

Rick Rodich    zone 4a.    Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA

Peden
Title: Member
Joined: 2012-01-04

Janet wrote:

The article was originally published in 2003 in the Rock Garden Journal, but it's available for downloaded on the SRGC site (http://www.srgc.net/forum/index.php?topic=4656.msg125155#msg125155).

What a fantastic art form! Thanks Janet for refreshing the link to this SRGC thread.

Michael Peden
Lake Champlain Valley, zone 4b
Four and a half months frost free
Snow cover not guaranteed

IMYoung
Title: Member
Joined: 2010-01-31

A little "advert" for the resource available on the SRGC site      ;)

http://www.srgc.org.uk/monthfeature/feb2004/content.html
describes a revamp of some raised beds after inspiration from ZZ. These beds can regularly be seen in Ian Young's Bulb Log Diary .

All SRGC Journals, from the first up to July 2010, freely available online. There is a full  Index as well - all on this page :
http://www.srgc.net/site/index.php/extensions/journal

A tremendous resource - and not just for crevice gardens!  I commend it to you. 

Cheers,
Maggi

Ian  and/or Margaret Young ( -here it is usually Margaret)

Aberdeen , North East Scotland, UK
Zone 8a

www.srgc.net

McGregorUS
McGregorUS's picture
Title: Guest
Joined: 2009-12-18

Using tufa for crevice gardens is completely different to using much less porous rocks. Tufa will allow an exchange of moisture from itself to the compost surrounding it. The exposed surfaces of tufa will have higher evaporation than a non-porous rock so the moisture dynamics of a tufa rock garden are very different to a crevice garden built from something much less porous.

To go all the way along this route - image a crevice garden built with peat blocks. The peat will hold and give up moisture. Using loam in the cracks is one way round the problem but it does not encourage deep root growth down the crevice in the same way that a better drained compost and less porous rock will.

Malcolm McGregor
Global Moderator/NARGS Editor
East Yorkshire, UK

Peden
Title: Member
Joined: 2012-01-04

RickR wrote:

Baldasarre Mineo give the same advice for very narrow crevices.

Good thought. I think if you use too much native soil and rocks are not close together you may run the risk of creating a tufa glorified perennial bed. You must ask yourself while building your new garden; "what am I doing differently". If you wish to grow plants other than those you are already growing in your other rockeries or raised beds or wish to grow plants that are always dying in those same conditions, you must ask yourself this. A narrow crevice suggests more rock, more raw mineral surface as well as less native soil and that IS different. I've questioned the common usage of sand with the same thought in mind; if the crevices become spaced too far apart is not simply a glorified sand bed being created? There may be good consideration in the SHAPE of the planting space that mitigates these concerns, people who grow plants in pots may think more about this than we who grow in gardens do. The tight, quickly drained/dried planting pockets created by the crevice garden may, indeed, have quite a bit to do with its success regardless of the fill mix, and crevices/pockets over an inch wide may actually be just fine. These larger pockets might essentially approach the growing conditions in a rock walled raised bed, which is, indeed, a tried and true method for growing rock plants.

Michael Peden
Lake Champlain Valley, zone 4b
Four and a half months frost free
Snow cover not guaranteed

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