Scottish Rock Garden Club Forum
Specific Families and Genera => Saxifraga => Topic started by: WimB on July 11, 2008, 04:15:39 PM
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Last week I visited an open garden of a member of the VRV (Flemish Rock garden society) and there I saw a beautiful trough with only saxes. So I ordered 10 Botanic saxes from Alpigena nursery to put in a trough.
Now my question is: what is the best soil-mixture for growing saxifraga's?
@Maggi: if you think this topic would be better with the topics of composts you can place it there but I was in doubt about where to put this topic.
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Wim, I think the topic can stay here... if you don't get enough response , then I can move it later!
I can tell you that we use the same mixture for our troughs with saxifragas as for others with alpines.... it is simply our general bulb mix, too! http://www.srgc.org.uk/bulblog/log2007/260607/log.html
By volume: two parts gravel ( 6mm grit) one part leaf mould, two parts sand, we find many plants are very happy in this mix.
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Dear Wim,
Think: Lean/Mean/Well-drained.
Try: Saxifrages from Scratch, by Malcolm McGregor (available from Saxifrage Society- http://www.saxifraga.org/ )
or Saxifrages- A Gardener's Guide to the Genus, by Winton Harding (available from The Alpine Garden Society http://www.alpinegardensociety.net/ )
If you don't want the expense of buying these, I could send you photocopies of the relevant pages.
Giles
The first, has cultural information; the second has lots of colour pictures. Its worth getting both if you can afford it.
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I more or less agree with Maggies compost mix. My own variation would be 1 part loam, 1 part leaf mould and 1 part (or more) grit.
Some saxifrages like some lime in the soil to encourage the silveryness of the leaves. My soil, and I guess Maggies also, is so neutral that we can grow anything in the garden without having to worry too much about pH. You probably need to check your own pH, Wim, to make sure that it is not too far from neutral before mixing your plants in the one compost.
As I said, I don't have to take much interest in pH and so am not an expert on the needs of plants but would guess that if the pH is less than 6 or greater than 8 then the compost will need correcting, or you could use two containers.
If you are going to get serious about saxifrages then Malcolm McGregor has a new book coming out in August/September and should be well worth waiting for (Advert - I will have it in stock as soon as possible).
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Thanks for the info. I think I'll use the recipe of Maggi.
@ Giles: I would very much appreciate it if you could mail or email me the pages from those books. I'll PM you.
@ David: I've already ordered the book of Malcolm McGregor at Timber Press; normally it will be out in August.
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Wim, I think the topic can stay here... if you don't get enough response , then I can move it later!
I can tell you that we use the same mixture for our troughs with saxifragas as for others with alpines.... it is simply our general bulb mix, too! http://www.srgc.org.uk/bulblog/log2007/260607/log.html
By volume: two parts gravel ( 6mm grit) one part leaf mould, two parts sand, we find many plants are very happy in this mix.
Maggi,
Does it matter what kind of leaf mould? I assume it is finely chopped? I primarily have maple leaves---but they are very well chopped and semi-composted.
I have historically had a really hard time with my trough soil mixes---major issue is drying out in summer--and if I don't constantly water (most years except this one) the plants are terribly stressed---I wonder if David's mix might work better for me in my climate (very hot, sunny summers)??? I don't know enough about your climate to try to work this out.
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Yes, Kristl, more loam might work better for you..... we moved to the higher sand/grit content because we ran out of good loam and our weather is never so hot for so long that this is a problem.
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I made the trough and planted 10 saxes in it. Hopefully they will grow...
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Wim,
really surprised that no one mentioned limey grit. Many encrusted saxifrages love the stuff.
I have found some red porous volcanic rock quite good and have finely crushed limestone 3mm or 1/8" size. You can also get powdered agricultural limestone to add on top to supplement if you want to enrich the mix.
I guess its only granite that is more neutral. You have a nice looking topping similar to a three coloured limestone which I use.
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David
Rightly mentioned lime...
and Maggi's bulb mix does throw in a small amount volcanic rock which I found to be alkaline... it is not critical but helpful to add more as the growth will really improve as most of these plants grow quite slowly at least in my northern shorter growing season.
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Here's the same trough one year and some months later. I used the following potting mix: one part loam, one part compost, one part grit and one part riversand. Although our soil is quite pH neutral I mixed in a bit of limey grit and they seem to grow very well.
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They look quite healthy and happy to me Wim !!
Remember to post a picture when they're flowering next Spring ! ;)
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I'll try to remember, IF they flower :)
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I'll try to remember, IF they flower :)
They will when they look like that
Göte
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Really healthy looking plants, Wim, well done. We'll expect more pictures next spring.
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Wim - What generous troughs! Your saxs look as happy as clams.
johnw
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They all look very nice - the trough itself too Wim. There will certainly be flowers. :)
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Here are some pictures of the same trough, seven (of a total of ten) are ready to flower and one is already flowering, so first two pics of the trough and third a picture of the sax which is flowering already, Saxifraga marginata f. milica
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Reading from the top of this thread has made your 'one year and a few months later' post really inspiring Wim - the whole trough is absolutely enchanting and it's great so see the beginnings of your flowerings, many congratulations :)
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Reading from the top of this thread has made your 'one year and a few months later' post really inspiring Wim - the whole trough is absolutely enchanting and it's great so see the beginnings of your flowerings, many congratulations :)
Thanks :D
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There will certainly be flowers. :)
I told you so! :D
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There will certainly be flowers. :)
I told you so! :D
;D :P
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There will certainly be flowers. :)
I told you so! :D
Me too ;D
Göte
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I am unsure wether this is the right thread but I have a question.
I have no experience of growing in throughs but I find that in my climate I need to grow plants like this on sloping ground or in some kind of crevices.
In mild spells of the winter the soil tends to be still frozen (thus nil drainage) but the snow on top melts and/or it sometimes rains. The result is that water will collect in any pocket or depression and later freezes solid.
This seems to damage many small alpines. Now: a through is but a great pocket where water will collect. I would expect to have 2-5 cm of solid ice at the end of the winter.
Any comments?
Göte
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Göte,
I can't help you with that, we don't have temperatures which go as low as the temperatures in Sweden. Maybe you can make a trough with insulation?
Here's another sax in that trough which was flowering today:
Saxifraga burseriana var. crenata
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I love the way the flowers pop up from that tight knit cushion Wim - how big will the cushion be?
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Robin,
I don't know how big it will get but now the cushion is only 7 cm in diameter.
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I don't know that I can comment intelligently Gote except to suggest that the trough should have a really free-draining, gritty mixture in it and good holes in the bottom so that while the water is still unfrozen, it doesn't accumulate anywhere and by the time it freezes, there's no "free" water in the trough, only dampness in the compost itself. Building up the surface of the trough should keep water off the surface but in your frozen winter, plants close to the top which become frozen may suffer root damage. I don't know.
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Thank you both for thinking about the problem.
Unfortunately it is not possible to insulate against the cold. That will only work for the odd cold night in the spring when the daily mean temerature is above zero C. (unless I install soil warming).
This winter we had many days if not weeks when the temperature was hovering between -10 and -20°C
If the soil is frozen, any free water on top will freeze when trying to drain down, much as icicles forms when water moves from above zero to below, and the open spaces will soon be filled.
As I wrote: My general way of handling the problem is to make sure the water can run off the frozen surface. The problem rfers to evergreens. plants that go dormant below surface do not seem to suffer.
Snow is now receeding and exposing Eranthis, Galanthus and Leucojum in flower or at least bud. :) I am anxious to se what happens when the hellebores can be seen.
Cheers
Göte
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And another one flowering in the same trough:
Saxifraga marginata from the Betcho-pass
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a through is but a great pocket where water will collect. I would expect to have 2-5 cm of solid ice at the end of the winter
Gote,
In Ontario, where the winters were much colder than yours, and mid to late winter thaws and re-freezing were common---I actually found that plants in troughs did better than those in the ground. In fact over the 20 years or so I had a large trough collection, losses could be counted on both hands---and these were rarely winter losses, but mid-summer heat & humidity rotting of saxes.
In the very hot conditions of our summers there, I tended to use a richer, slightly heavier soil mixture in the troughs, topdressed with rock mulches. I have no idea if this contributed in any way to the successful overwintering.
Also, as Leslie has mentioned, I always plant *very* high initially, so that even after years of "sinking" the plants are still above trough lip level.
Here are some examples of troughs photographed this morning, planted perhaps 10-15 years ago and you will see that most of the saxes are still reasonably high---although for aesthetics, I would prefer for them to be higher still.
After record breaking heat the past two weeks, we are returning to lows of -15C in a few days.
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Those look very good Krystl, and the saxes obviously not planted yesterday. I have great hopes of my new trough crevices which are up to 15 cms above the surface level of the troughs. Once the roots bury down, they seem to be fine and the tops so much safer. Planted at surface level without rocks, they simply burn to death and very quickly. One good hot, windy day will do it.
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Planted at surface level without rocks, they simply burn to death and very quickly. One good hot, windy day will do it.
Not only that.... troughs planted in that way look so boring!
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a through is but a great pocket where water will collect. I would expect to have 2-5 cm of solid ice at the end of the winter
Gote,
In Ontario, where the winters were much colder than yours, and mid to late winter thaws and re-freezing were common---I actually found that plants in troughs did better than those in the ground. In fact over the 20 years or so I had a large trough collection, losses could be counted on both hands---and these were rarely winter losses, but mid-summer heat & humidity rotting of saxes.
In the very hot conditions of our summers there, I tended to use a richer, slightly heavier soil mixture in the troughs, topdressed with rock mulches. I have no idea if this contributed in any way to the successful overwintering.
Also, as Leslie has mentioned, I always plant *very* high initially, so that even after years of "sinking" the plants are still above trough lip level.
Thanks for advice
This about planting high makes a lot of sense to me. I have been reluctant to plant in containers also because the soil gets colder than in the ground but if it works in Ontario I feel tempted to try.
We had 23.6 one night this year. but that is pretty unusual
Cheers
Göte
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Gote,
The plants in the troughs have historically survived up to -40C, even totally exposed,
although the average was -30 to -35C. Go *much* higher than you feel naturally comfortable with when you first plant them. They really sink a lot, especially in the first 2 years.
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Gote,
The plants in the troughs have historically survived up to -40C, even totally exposed,
although the average was -30 to -35C. Go *much* higher than you feel naturally comfortable with when you first plant them. They really sink a lot, especially in the first 2 years.
I am afraid that I have now swallowed the bait we will see if hook and sinker follows ;D
Göte
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Two more flowering here in the same trough:
Saxifraga sempervivum f. stenophylla
Saxifraga x luteo-purpurea
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And flowering here again this year :D :D