dirtdorphins said:
What is the deal with troughs???
They are a classic method of alpine gardening, and a great way to create the sharp drainage, lean soil, or particular special conditions* needed to grow certain plants that require it, without having to resort to building larger scale, in-ground beds.
* E.g. To create acidic conditions in an area with alkaline soil and groundwater, where in-ground beds could not be maintained, as they would become alkaline with time due to the groundwater (or vice versa - alkaline beds in acidic areas).
dirtdorphins said:
What is the difference between a trough and planter?
Both are "planters" but troughs have the advantage of durability (for decades* or centuries**) as well as providing mass for insulation. Size ( perhaps better stated in terms of volume and vertical height) is also a factor in providing the necessary insulation in a cold climate... and I suppose also in warmer climates, to reduce temperature change effects there too?
* E.g. Hypertufa troughs, if made properly.
**E.g. Stone troughs, for those so fortunate as to have such things.
dirtdorphins said:
Where does the word trough come from and why is it that alpines are planted in troughs as opposed to containers or planters?
In the UK, in the heyday of the alpine gardening craze in the early 1900's, when plant explorers were returning from collecting trips with exotic alpine species, stone troughs (for feeding and watering livestock) and discarded stone sinks began to be used as planters, presumably for the same reasons as stated above (creating a small area of special conditions; durability and mass).
dirtdorphins said:
Why couldn't one create sharp drainage, lean soil, or special conditions in general in something other than a trough, per se?
Sure, no reason why not, while keeping in mind the benefits of durability and insulation.
dirtdorphins said:
What are the mystical/magical properties of tufa troughs or hyper-tufa troughs? Could one use a concrete trough? (I planted stuff between the rows and in cracks of concrete in my old barn foundation--some were raised/some were not--were these troughs and crevices?) Could one use other soft stones i.e. pipestone or really soft sandstone?
The mystical/magical properties are mainly drainage (troughs are elevated above the ground surface) and the essential fact that it is a separate container that allows you to create conditions that may not be naturally present in your area. Hypertufa troughs can be made to look quite a bit like natural stone, which is also very desirable.
An actual "tufa" trough would be a real stone trough made out of a particular type of very porous limestone deposit (tufa)... these are probably rare as hen's teeth, since tufa deposits are similarly rare in the UK (where the benefits of alpine gardening in troughs were first realized).
The linkage of the word "tufa" with "troughs" refers to man-made troughs, where one is using a "hypertufa" mix to try to achieve the porosity and relative light weight of tufa, while getting the other benefits of a real stone trough (durability and mass). The use of hypertufa mixes make the troughs a little lighter and easier to move around (but don't kid yourself, they're still bloody heavy when filled with soil and rocks!), as well as the trough itself being permeable due to the somewhat porous material which helps drainage.
All hypertufa recipes contain cement (and the crappy ones don't contain enough!!) Sure, you could make troughs of cement and aggregate - concrete in other words... just don't ask me to help move 'em.
(My hypertufa ones are heavy enough
).
Sure, cracks in your concrete barn floor could be thought of as crevices (though I imagine any roots would have very quick access to regular soil beneath) but they certainly weren't troughs.
Yes, one could use soft stone to make troughs. With all the effort it would take, you'd certainly want to choose the right stone. For example, a sandstone that was soft because it was very muddy and poorly lithified might actually break down surprisingly quickly (there are some deposits here that are poor material for construction and even for rock gardens due to this). By contrast, a highly-quartzose and well-lithified but porous sandstone would probably make a really good porous and durable trough.
dirtdorphins said:
What are your troughs made of? (They look like they've held up well for many years. I've heard that hyper-tufa can fall apart after a winter or two. What can you tell us about 'winter-hardy' trough construction?)
Yes, crappy hypertufa can indeed fall apart rapidly... and unfortunately, has given hypertufa in general a bad rap. Good, durable hypertufa depends on two things - the hypertufa recipe (the proportion of cement to other materials) and how the mix is handled (as I mentioned previously in answer to a question from Fixpix in the Photos thread).
We have hypertufa troughs that are perfect after 16 years outdoors in a zone 3 climate with frequent freezes and thaws. Other alpine gardeners here have older ones. These would be examples of using both a good recipe and good handling of the mix during construction.
We also had the "chocolate brownie trough" - a crappy hypertufa recipe off the internet that DH used against his better judgement. (He couldn't fathom how the recipe could be claimed to make anything durable, so he gave it a try...) Not enough cement in the recipe - you could crumble the sides with finger pressure - and an overdose of brown concrete colouring gave the trough its nickname. Even so, I did plant it up, and it took many years of slow decomposition before I finally figured I'd best move the plants out. In retrospect, it may have been largely "angle of repose" holding it together.
We also have a couple of troughs that have spalling occurring at the top edge - these are examples of good hypertufa mix but bad handling. We ran out of mix while filling the forms and had to mix up another batch to fill the last couple inches, which did not bond completely to the first one (a bit of a flaw in the volume estimation there, I guess...) So, to repeat, durable hypertufa troughs are very achievable but depend on the proper mix
and proper handling.
Re. recipe, can't remember but I'll get it from DH and post it here later.
dirtdorphins said:
Do the troughs have drainage holes or do they just 'leak' some other way?
Hypertufa troughs are normally made with drainage holes in the bottom. (I presume that real stone troughs were probably drilled through to provide drainage prior to planting use.)
Fish-box troughs are another version of alpine troughs that many people find useful and durable. I have no experience with them, but maybe Rick can talk about them?
Edit: I realized I transposed "cement" for "concrete" and went back and corrected it... and then thought of other things to add.
