Scottish Rock Garden Club Forum
General Subjects => General Forum => Topic started by: Tim Ingram on October 01, 2011, 06:28:09 PM
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Extending the sand bed
Gardening with trees and shrubs, or even perennials, requires more space to move into as your fascination with the subject expands. With alpines at least small incursions into the lawn pay big dividends! (If your other half is not there to remind you that there are many other more important things that need doing!). The relatively small sand bed in our front garden is now pretty full and new acquisitions this autumn really require room to show themselves off. To extend the bed is quite easy, as the photographs show, but even this very small area has required the removal of around half a ton of soil and infilling with fine sharp grit. A hard morning's work!
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The 'sand' used is very fine potting grit derived from shattered flint and the picture below shows this in close up. It would be interesting to compare results with sharp sand or ballast as more normally used. As I have mentioned before it is probable that these would hold more moisture and require less watering than I have had to do in dry periods. I have two large pieces of tufa left over from a previous raised bed and therefore have added these to provide some relief. It would have been very nice to use a lot more tufa associated with the bed, and David Sellars, a North American grower with experience of sand beds and tufa recommends that the two associate very well. I imagine there would be very good transfer of moisture from deep sand to blocks of tufa. Even the two blocks here make an appealing feature.
Positioning plants and planting them is very enjoyable and easy in sand. I don't wash the roots of soil as some growers recommend, but do pay close attention to watering the newly planted area over initial weeks. It can then take a year or even more for some plants to really establish and grow away, but as a consequence they stay tight and in character and much less prone to pests and diseases.
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Well done Tim !! I always find it exciting to have more planting space available ?? Especially with such a variety of gems waiting to find a suitable spot !! :D
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The 'sand' used is very fine potting grit derived from shattered flint and the picture below shows this in close up.
My, yes, that is very sharp looking stuff. You'd hope cats and slugs would find it very uncomfortable, wouldn't you? ;D
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Looks like something I should try .... we have pure sand only a couple of feet down already. Maybe I would need to pay attention to watering for longer than a year! In spring 2011 plants which had been planted out almost a year earlier began to curl up as drought took hold.
Where do you buy that lovely looking sand? Here the sand at garden centres is relentlessly (sandy) orange in colour.
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Tim, I presume the sand will weather to the same colouration as the rest of the bed?
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Thanks Luc - things can happen quickly on this forum! I have been inspired by your tufa blog but have yet to get my tufa!! So for the time being I am devoting my attentions to the sand bed. Maggi - It is certainly true that slugs seem deterred as all of the campanulas on the bed are untouched! Fortunately we have no cats around; I think they might find it more amenable! I think the great variation of particle size is a good benefit and must help in holding moisture by capillarity. Tony - the 'sand' is left over potting grit that we had in bulk for the nursery. It is heat shattered flint (Canterbury Spar) and, I think, is the fine stuff left over when they have graded out the material used for rendering house walls and the like. I am not sure if it is readily available outside our area? Martin - as fast as I aim to reply I am beaten to it!! No what I have done is to surface the bed with 6mm gravel, partly because the fine grit is rather bright and partly to improve the aeration around the crown of plants. Each year I topdress with another layer of gravel so this gradually becomes deeper. I think it is a particular benefit for certain plants like the daphnes over winter.
This new area provided space for about 25 plants and there will be the opportunity to establish more in the tufa blocks (which have ready made holes in situ!). They should have a month or more of good growing weather to begin to establish and around the end of October the bed will be covered with Dutch lights through to early spring. Little if any watering will be necessary over this period unless we have long unseasonably dry and warmish weather (usually in late winter turning into spring).
What of the plants? They vary considerably and with a number I am being quite adventurous! They include several choice campanulas that generally succeed well in sand, silver saxifrages, succulents like Delosperma cooperi and Rhodiola trollii, dianthus, onosma (often short lived but very appealing), Pulsatilla vernalis (again! - I would really like to establish this), and a good number of others from various genera. With other sections of the bed drawings have been made to keep a record of the planting (particularly important when one wishes to propagate from the plants, as is a primary aim of the planting). In the digital camera age I have just begun recording newly planted sections of the garden photographically and appending plant names on a wide border around printed copies. However much one thinks names will remain in the mind they quite quickly become lost unless plants are being managed all the time. After what seems quite good success with many plants on the initial planting of the bed, I look forward to seeing how this new planting develops next spring (and keep my fingers crossed that no rabbits discover it!).
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Tim it seems that your sand bed is roughly at the same level as the lawn.Does it not drain the humidity from the surrounding area and fill with water at the bottom in the winter,or is your soil very free draining?
Till now I have constructed all my sand beds one foot above the ground but it is a core to water them in the summer and most of the time one is not even allowed to do so.Therefore I was thinking of lowering them down but my soil is heavy clay and I am afraid I may lose plants in the winter, even with a cover,because the roots may be too wet.What do you think?
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I wish I had space to make a sandbed!
Unfortunately I have to clear my woodland to get space but that is out of question or the time being - there are some choice woodland plants too ;)
However I had the same thoughts as John85: Your subsoil has to be very free draining. If I had made a bed like that (same level as the lawn) I had gotten a lake in fall even with a rather free draining subsoil.
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John - I deliberately made the sand bed below soil level because we do have naturally well drained soil and a dry climate and I hoped that this would keep the sand moister during hot and dry summer weather (not really too different to the traditional scree which is normally made at ground level). Even so I have had to water quite often this year, although this is largely because many of the plants are still small and haven't established a deep root system. In winter I have found cover is essential to prevent the bed becoming too wet, though that is mainly because I am trying some pretty choice plants in it. (Growing in tufa or a crevice garden would probably enable many more plants to be grown without cover). On heavier clay soil I would definitely construct a bed above ground level. Since watering sand is very easy and the plants so special I think it is as valuable to keep an eye on this in the garden as it is in the alpine house or troughs (I have the fern Asplenium ceterach on the bed and this is a good indicator plant of drying out, though I don't usually leave watering this long!). Again I would cover the bed in the winter and have even toyed with the idea of an all year round covered bed for plants from really dry climates (viz: Roy Elliott's famous tufa wall), but this would require some sort of dedicated watering system so becomes a more complex exercise!
Trond - I think sand beds can come in any size! From Peter Korn's quite epic scale down even to troughs or a small raised bed (but I have to admit I have neglected some other parts of the garden while I have had fun doing this, hence my wife's slight admonition).
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Cracking job there Tim. Can I just clarify please when planting do you plant into the sandy gravel or plant first and then dress with gravel?
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Both actually David. In the established bed extra plants go into the topdressed sand, whereas I initially plant them into the sharp sand when sections of the bed are made. Watering soon washes the finer sand down through the gravel.
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Fascinating to see the different (and successful) methods gardeners use. I've used sand beds for years, but they are mounded rather than flat. The sand has a lot of "fines", which are the small gravels that are screened out for mason's sand, which must be uniform. When it rains, the fine grains are washed down with the "fines" on top. People think it's gravel, but all you have to do is brush the "fines" with your havd and you would see it's sand. The sand beds range from 2' to 4' deep, and the base is rock. They are not watered except new plants. It has been successful for many dryland plants which don't usually want to grow in the northeast. Hope you will add more photos in the spring.
p.s. I'm awed by your sharp edging line.
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Anne - really interesting to hear that your sand beds are so deep. I was hugely stimulated by seeing pictures of the Kelaidis's front garden, just taken over by 'berms' and with so many incredible plants. I have rather a long way to go to emulate this (and have a rather annoying interest in many other plants too so my garden lacks the dedication that many alpine growers have). I have always been fascinated by dryland plants of all sorts. I don't know how often NARGS members with similar interests visit the UK, but it would be great to organise a conference for AGS and other gardeners on these plants and ways of growing them. This style of gardening, and the wide range of plants that people grow, might have a broader appeal amongst keen gardeners than alpines alone (I think of gardeners like Beth Chatto who has had such a huge influence on so many of us).
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Tim,
I'd be intrerested in that conference! ;D Maybe something to suggest for Alpines 2021 in Scotland!
We use sandbeds in our garden to grow some of the Aussie plants from Western Australia that demand the extra drainage, but I'm also trying out Juno and Aril iris to see if they can stay dry enough that way over the summer even if we get a downpour.
cheers
fermi
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That's an interesting idea, Fermi. I might try it. I've wanted to try growing Junos for some time.
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Our front garden is gradually changing in its planting after seeing how well many plants have established in the sand bed. This section of the garden has undergone a number of changes over the years and has become full of self-seeding eryngiums, lychnis and a few other such plants. These look good as a 'meadow' type planting for a while in the summer but the space is really rather wasted. I am slowly clearing many of these plants, leaving significant shrubs like Potentilla fruticosa 'Beesii' ( a very nice form with silver-silky leaves) and a fine specimen of the western American Berberis haematocarpa. The idea is to surface the bed with a deep mulch of gravel, mounded quite high in the centre, and plant much more choice dryland species. The top end of the bed has been cleared and planted in this way and now it is the turn of the lower section. The front edge of the bed has always had a planting of alpines and bulbs (including the Crocus kotschyanus 'Albus' shown), which has always been incongruous with the stronger plants behind, so at last the picture should change.
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Like John85 I was wondering about the flatness of your sand garden Tim and had expected it would need to be up somewhat above the surrounding grass, perhaps mounded, as Ann (Astragalus) suggests. Assuming the grass is mown, how do you keep the mowing off the sand?
I have extensive gravel driveway which has gradually become more and more narrow as grassy type weeds have taken over the edges and left just the actual car tracks still of gravel. I think a good effect could be achieved by simply dumping a truckload of fine gravel (several, in fact) at stragecic points. If only Roger would go away somewhere for a couple of weeks..... :-\
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Lesley - the beds look flat but I am raising them quite significantly with sand and gravel, and keep top-dressing year on year. We have very well drained soil so I think it is less important to raise them higher (but also a lot depends on the plants being grown and I am experimenting quite a bit here). I don't really see the sand bed as being greatly different to a more traditional scree and have written more about it for the forthcoming AGS Bulletin. Our driveway is solid under gravel so weeds are not too much of a problem but an acquaintance developed an alpine planting in the middle of his drive, between the wheels of the car! Rather ingenious and making the very best use of space.
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Tim,what is the plant Crocus kotschyanus is growing through?
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Like John85 I was wondering about the flatness of your sand garden Tim and had expected it would need to be up somewhat above the surrounding grass, perhaps mounded, as Ann (Astragalus) suggests. Assuming the grass is mown, how do you keep the mowing off the sand?
I have extensive gravel driveway which has gradually become more and more narrow as grassy type weeds have taken over the edges and left just the actual car tracks still of gravel. I think a good effect could be achieved by simply dumping a truckload of fine gravel (several, in fact) at stragecic points. If only Roger would go away somewhere for a couple of weeks..... :-\
Lesley, that actually works very well. My suggestion would be to make the gravel mound high and sculpt it to your liking. I've used 1/4" gravel (which contains a lot of coarse sand), and it worked very well. You never have to worry about drainage and most sensible weeds prefer something with actual soil. The american western plants shine in this situation (eriogonums, erigerons, penstemons, astragalus etc.).
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Thanks Ann, I think I'll be requesting a load of fine gravel for Christmas. So much more useful (to me) than household appliances, perfume etc.
I like the garden between the tyre track idea too. Surely an ideal place for a collection of crocuses. :D
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In our driveways we have slabs for the car wheels to run on and over the last twenty or more years we've been seeding plants and bulbs into the gravel of the surrounding area. These areas were too hard packed to allow any proper cultivation of the soil and so the seeds have had to make their own way in life in conditions that are far from ideal.... there are photos in various Bulb Logs over the years of the wonderful floral feature this has provided. By comparison a sand bed must be real luxury for the plants!
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I just finished a new sandbed. Today I planted a lot of bulbs, Allium, Muscari, Juno, Onco, Tulips and some other. In the winter I will sow a lot of species directly in the gravel and then fill it with mostly cushion plants in the spring.
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I just finished a new sandbed. Today I planted a lot of bulbs, Allium, Muscari, Juno, Onco, Tulips and some other. In the winter I will sow a lot of species directly in the gravel and then fill it with mostly cushon plants in the spring.
Just a little one, then, Peter?!! :o :o 8)
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Suddenly all the other beds were tiny.
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Ian says he remembers that the area of exposed rock at the top left that you had dug out was over 2 metres high..... :)
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I had to dig out 0,5-2,5m of soil to find the cliffs. It will be a 6-7m high southfacing scree and a small northfacing scree (up to 2m) on the other side of the ridge.
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I had to dig out 0,5-2,5m of soil to find the cliffs. It will be a 6-7m high southfacing scree and a small northfacing scree (up to 2m) on the other side of the ridge.
OH!!
This is more than gardening, it is truly landscaping.
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Landshaping...
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I started to dig in the autumn 2007.
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I started to dig in the autumn 2007.
Wow, Peter, that is phenomenal! I last saw your garden in spring 2007 and I hope we can get over to Sweden after the Prague 2013 Conference!
cheers
fermi
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Maybe before the Prague event :)....
" Every ten years, Sällskapet Trädgårdsamatörerna (the Swedish Society of Amateur Gardeners) arranges a conference with an alpine theme in collaboration with the Alpine Department at the Botanic Gardens in Gothenburg. The next occasion will be from 30th May to the 1st June 2013. The conference includes exhibitions of plants and plant photography, visits to local gardens, plant sales and a series of lectures".
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I must admit to being truly astonished by Peter's 'landshaping'! This is gardening on another scale and immensely inspiring. Even in my much smaller and less dramatic garden though I have got huge satisfaction from our sand bed, and so much comes from discovering the ways that give plants what they need - easier said than done often!
John - the groundcover beneath the crocus is a thyme whose name I have lost. At Sissinghurst they have a small bed devoted to thymes which is fascinating to watch in the summer when bees are attracted to the flowers. I am not sure they grow them on sand though and have to renovate and replant fairly regularly.
Maggi - I shall make a note of the dates of the conference in Sweden, but two years is a long time to wait!!
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Maggi - I shall make a note of the dates of the conference in Sweden, but two years is a long time to wait!!
Ahh, but forward planning is a wonderful thing! ;D ;D
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Tim, I have the Nerds day the 5th of May next year. Then you don´t have to wait that long...
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Tim, I have the Nerds day the 5th of May next year. Then you don´t have to wait that long...
So thoughful of you, Peter!! ;) ;D
http://www.srgc.org.uk/forum/index.php?topic=8026.0
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Curses! We are opening our garden on the 6th and 7th May. I would have loved to come to your Nerds day. I will try to persuade the family we need a holiday in Sweden next summer. Good wishes for the day.
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We are having a glorious and warm autumn in south-east Britain, but around this time I normally think of covering the beds containing more choice alpines. Many would probably be alright without but our relatively mild stop-start winters can be a real problem. So the sand bed is being covered with a simple structure of dutch-lights, nice and airy and open. Looking up from below you can almost 'feel' the enjoyment of the plants (if that is not being too poetic!).
When doing this it is advisable to carefully mark what goes where (!), so that it all goes together again easily the following year. A few bracing joints between the posts at the ends, make the structure fairly rigid. And then it will stay until around March time next spring, dependant on the weather.
Many gardeners may think it a hassle to go to such lengths but it does allow so many more more choice species to overwinter in the absence of prolonged snow cover, and only takes a few hours to put together.
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The mild winter has made it possible to do a lot of planting in the new bed. Now I just have to cover it with gravel.
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I have nothing but admiration for your accomplishments Peter ... having seen your excellent lecture at Birmingham I am now determined to visit your magnificent garden in person at the earliest opportunity.
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You are welcome.
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Peter - how is it you are able to grow so many choice plants without some form of winter cover? I'm thinking of species like Lewisia tweedyi and Pulsatilla vernalis, and also many of the dryland alpines. Is it because your sand beds are on such a scale and top-dressed with coarse gravel? It reminds me very much of Alan Furness's garden in Northumberland, which is made in a similar way but with varying grades of gravel, and with the same sensitivity to the requirements of the plants. If only I was starting my garden again....!
However long will it take you to top dress this last sand bed?!!
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Tim, in the beginning I covered my plants in the winter but I have not done it for the last 12 years. P vernalis is native to Sweden so there are no reasons to cover it. Lewisia tweedyi likes a dry summer and then it can take a lot of rain in the autumn. I have lost some plants when I stopped covering them but very few. A big bed makes a difference... And it has to be a slope. Why don´t you start your garden again?
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I am sorely tempted if we could buy the field next to us!! It would really wake up alpine gardening in the UK to see growers breaking new ground like this. Hope to visit in the summer.
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Buy the field and build your own mountain range...
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Buy the field and build your own mountain range...
... If you need any Alp! :D
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Everybody needs a alp.
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Well the garden is covered in snow at the moment - time to tidy up the greenhouses and sow lots of seed (even if a little late for some to get a long enough cold spell). Couldn't resist posting this image of Silene hookeri on the sand bed last year, having got it out for another reason. I probably won't be building a new Alp, but do intend to start extending the beds in the spring - our garden may change in the next year or two!
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I have enjoyed making the small sand bed in our garden so much, and it has been so much more successful at growing some of the more choice alpines, that extensions are underway! This is only a small part of our garden but holds such an inordinate amount of interest. Because I cover the bed in winter (from November to March), I have invested in 50mm Metposts to hold the supports for the dutch lights, and this has made a vast improvement to the look of the bed, even though quite costly. Many of the plants on the bed are familiar and not too difficult to grow, but the sparse growing conditions (just like a scree) keep them slow growing and more in character.
Some examples:-
Polygala calcarea 'Lillet'
Androsace laevigata and its wonderful hybrid idahoensis x laevigata (both from Aberconwy)
Primula marginata 'Clear's Variety' and 'Shipton'
Pulsatilla ambigua from Desirable Plants in Devon
Woodsia obtusa, one of several small rock ferns that do well on the bed
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This (the Metposts) seems like a good idea, Tim. This way you need only have the actual posts in place when the covers are needed. How will you stop the post bases getting clogged in the meantime?
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Metpost make plastic and steel caps that fit snugly over the posts, Maggi.
Tim, your garden and images are equally beautiful.
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Metpost make plastic and steel caps that fit snugly over the posts, Maggi.
Ahhh, that makes sense. :)
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Tim,
that P. ambigua is stunning and not often seen!
Very lovely. 8)
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That's new to me - thanks Cliff. The bottom of the Metpost slots do have holes for water run off, so smaller grit etc will get washed through.
Armin - yes I am very taken by pulsatillas and try to grow as wide a range as possible, some less well than others. Species like alpina and vernalis I don't find easy, ideally needing cooler and moister conditions. I don't know how variable ambigua is in colour - really the only form I have seen is the lovely soft pink variety which is often exhibited.
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I don't know how variable ambigua is in colour - really the only form I have seen is the lovely soft pink variety which is often exhibited.
That soft pink form is a beauty...a photo by Liam McCaughy of it featured on the cover (and inside in a piece by Harold McBride) of IRG issue 14 February 2011........
http://www.srgc.org.uk/logs/logdir/2011Feb241298591020IRG14_Feb_2011.pdf
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Tim,
I've only just discovered this topic. Impressive! (to say the least). I'd have to build a sand bed on top of the ground here.... our clay subsoil would just make a lovely sandy swamp were I to dig a sand bed into it. ;D You have so many lovely jewels growing in yours! :o
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Species like alpina and vernalis I don't find easy, ideally needing cooler and moister conditions.
Tim,
I agree, difficult to please. Beside cool conditions P. vernalis & P. alpina (ssp. apiifolia) like calcareous free soil.
I wish you a good seed set on the P. ambigua.
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I'm glad you menmtioned the line-free soil Armin. I have young plants to go out and probably would have added some lime as P. vulgaris likes it. ::)
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Lesley,
if you have seedlings P. alpina ssp. alpina (white flowering form) they grow in nature over lime stone and should not make troubles.
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I have seedlings of both (I hope) the white which came as P alpina and as P. alba, and of P. alpina ssp apiifolia. Does it prefer to be lime-free Armin?
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A lot more plants are coming in to flower. I particularly like the groupings of species that develop over time - for example Polygala calcarea 'Lillet' with raoulia, dianthus, campanulas, asperula, dryas and primulas. The polygala vies with the best gentians for that true blue on the bed and is a lot easier to grow. Foliage is always interesting close up and Arabis androsacea more than lives up to its specific epithet. The smaller androsaces are very slow on the bed but mucronifolia x semperviviodes is flowering nicely. Even more striking though is the superb dianthus hybrid 'Conwy Star' from Aberconwy; wonderful flowers and also very fine glaucous foliage. Finally an overall scene of our front garden - not all tidy but lots to see.
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Excellent Tim.
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Absolutely brilliant, Tim. It looks great.
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Many thanks - a lot of inspiration has come from North America, but also from gardeners like Jack Elliott and reading Duncan Lowe's wonderful book. Curiously though few visitors to our garden over the years have become hooked on alpines, which I find very surprising. We hope that if we have more plants for sale from the garden this might begin to stimulate gardeners to experiment more in Kent. At least it will be interesting to find out.
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Very interesting Tim. Some growers seem to have had a lot of success growing Crocuses in sand beds, I wonder how Narcissi would fare?
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David - initially I didn't think of planting bulbs in the bed because I imagined they would need richer fare. However, there are a couple of crocus (not increasing greatly) and several small narcissi (bulbocodium and romeuxii). These latter grow and flower well and are self-seeding. On the whole though I think most bulbs would prefer a more traditional scree or raised bed, with fertile loamy soil to put their roots into.
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Really beautiful, Tim. I'd like to try the polygala. What a great blue!
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A few more plants are coming into flower now. Probably the largest flowered selection of Androsace studiosorum, 'Salmon's Variety'; Daphne x hendersonii 'Blackthorn Rose' (forms of x hendersonii have been a good success on the bed); Rhodanthemum 'African Eyes'; and a very attractive Aubrieta glabrescens MESE 536, from Parham Bungalow Plants, only small as yet but a glowing colour. My thoughts are turning again to a new combined tufa and sand bed as this original has no more space - an old raised bed built 25 years ago is sitting waiting!
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Complete with tufa Tim? Covet, covet!!
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First find your tufa! I'm still working on that...(actually first is to persuade my wife that we need a new alpine bed - that has worked well because we are aiming to propagate from the plants, and growing them as successfully as possible is a must).
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The sand bed has been rather eclipsed for the time being by flowering of Yucca whipplei in our front garden. Truly an extraordinary plant! The blue in the foreground is Lithodora x intermedia, a favourite for many years and below the yucca is Triteleia ixioides, a really good early summer bulb.
On the sand bed itself there are a number of nice things - Penstemon rupicola 'Conwy Rose', Onosma echioides, Hypericum cerastoides, Thymus 'Peter Davis' and Astragalus angustifolius. Makes me think that a small outdoor garden at Chelsea on this principle could be a welcome change!
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Must be a tad tricky to concentrate on much beyond that fab yucca!
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I do so enjoy this thread Tim and one of these days must try to get round to constructing one of my own.
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Many thanks David. I have to say our gardening is probably rather extravagant (having started very young), but I think the great thing about sand beds, crevice beds and so many other ways of growing alpines, is how they adapt to any sized garden - the trick is making something that satisfies you rather than following too much the strictures of others. Of course once success in growing the plants comes your way, the garden seems to expand without you noticing...!
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Yes that Yucca is pretty stunning. I saw lots of Yuccas in Texas and thought I must try some some so when seed has been offered in different exchanges I have ordered some packets over the years. The first one has come up to flower - lost tag in meantime - and it is a fairly common one around here!!!!