Growing alpines in a wall....

[SueStephens]

Could anyone help me with a method for growing alpines in a wall?

I have a very long 8' high stone wall with deep spaces in between the stones. I have tried growing some lewisias in the crevices but they don't look very happy. In fact, I think that they are almost at death's door. I must admit that I didn't do anything other than take them out of their pots and stuff them in and hope. I can almost hear your combined sharp intake of breath!

Perhaps I should have planted some less mature plants having put some compost mix in the wall to start with? Or tried sowing some seeds directly. I cant fill the crevices completely because the wall is also home for a colony of bats. Any advice would be really appreciated.

Sue

[Tim Ingram]

I think seed could be a good way if you chose plants that grow naturally in such places - eg: wallflowers, some campanulas, valerian (but this is probably too big!) and quite a few rock ferns. I've also seen Convolvulus cneorum growing wonderfully high up on a wall at Sissinghurst and silver saxifrages could be good. If there is enough soil and moisture for plants to establish probably many other things might do too. The good thing about seed is that plants will naturally establish in suitable spots, but it might take some time. Is there anything in the wall at the moment?

[SueStephens]

Yes, I think that valerian might be a little OTT... But I take your point about growing plants that naturally grow in walls. At least I would have a chance of success.

At the moment it has rather a lot of Cymbalaria muralis which was welcome to begin with but is now taking over. Luckily, it is easy to pull out.

If I used seed, then I wonder how I would go about it.... Perhaps I should fill some of the crevices with a sandy compost mix? But how would I get the seed in... I read somewhere that the the RBGE peat wall was seeded by blowing it into cracks. That seems a little too hit and miss to me. I wonder whether germinating seeds in vermiculite and then sowing them in the wall would give my a better chance of success?

[Darren]

Yes, I think that valerian might be a little OTT... But I take your point about growing plants that naturally grow in walls. At least I would have a chance of success.

At the moment it has rather a lot of Cymbalaria muralis which was welcome to begin with but is now taking over. Luckily, it is easy to pull out.

If I used seed, then I wonder how I would go about it.... Perhaps I should fill some of the crevices with a sandy compost mix? But how would I get the seed in... I read somewhere that the the RBGE peat wall was seeded by blowing it into cracks. That seems a little too hit and miss to me. I wonder whether germinating seeds in vermiculite and then sowing them in the wall would give my a better chance of success?

I'm told Farrer used a shotgun to sow seeds in his cliff at Ingleborough. There's an idea for you, but please don't tell the nice policeman you heard it from me 

The problem with mixing seed with compost would be the compost washing out or the seedlings depending on it and refusing to send seed out into the crevices as you would like.

How about mixing seed into a small ball of sphagnum moss and cramming it into the crevices to hopefully prevent the birds pulling it out again?

[Palustris]

The method suggested in the AGS Bulletin, many hundreds of years ago, was to wrap the seed in a ball of wet clay. This glued the seed in place and kept it moist until it germinated. Never tried it myself though, never having had a wall to plant up.

[SueStephens]

Yes, I was thinking that I would need to find a way of 'gluing' the seed in place. I could try moss... But there is a risk that the blue tits that nest in the wall would take it for nesting material...

[Martin Baxendale]

This may seem an obvious question but is it a retaining wall with soil/subsoil behind are free standing?

[SueStephens]

It is a retaining wall... Recently constructed but before we moved here... It is faced with rock but has breeze blocks behind so I think that the plant roots would have very little chance of finding their way to any soil.. This is a rather poor photo of the wall... But you will get an impression.

[Tim Ingram]

I've seen a wall halfway up Snowdon covered in a wonderful variety of ferns. These would need little sustenance so if you could get small plants and hold them in place with clay that would probably work - Asplenium ceterach, the Rusty Back fern, is tremendous and grows well in my sand bed. Rachel Lever at Aberconwy often grows a wonderful range of these. Campanulas could be good because they tend to run around and so again don't need a lot of soil - this one is in an old wall near us in Faversham. And succulents like sedums, sempervivums and Umbilicus would presumably establish. I like the idea of blowing seed at the wall - a good project for kids to try!

[John85]

I was also going to suggest sedums:I just pushed bits of it between the stones with ordinary garden soil and they rooted easily.
Why not drill some smalls holes through the breeze blocks?
What is the plant on your diaporama just before the frame and the ladder?Is it a valeriana?

[gote]

It looks as a wall built without mortar. Then it is not too difficult. Use a crowbar in a horizontal slot. Lift the stones a few millimeters and push the plant in. you have to be pretty sure that it has contact with the soil behind so you will probably have to push in some compost as well. an old table knife is a good tool. You wil have to be very unkind to the roots. They need to be teased apart so they stretch as far as possible The planting is best done when the weather is rainy and going to stay rainy and cool. Some plants should be pruned to make sure the roots are not overloaded. .  The following do well in a wall.
Draba aizooides and repens, Thymus serpylllum, Saxufraga hostii and aizoon (or whatever they are today), Asplenium trichomanes and ruta muraria. Edraianthus pumilio and others, Aubrieta sp. Sedum aizoon..... There are many more. The easiest subject is probably Corydalis (pseudofumaria) lutea It can be invasive but is easily pulled out. It is not true that it is a shade lover. It grows on old wineyards in Bavaria.
Hope you post photos of fantastic growth in a couple of years.
Göte
   

[SueStephens]

So many wonderful ideas... thank you everybody.

I love that photo of the Campanula and I am begining to think that that might be the way to go. I dont want to plant too many different flowering species because it might end up looking too unnatural...

Asplenium and Umbilicus grow in the wild all over the place here. I think that Asplenium trichomanes  has already taken up residence.

It has just occured to me (pity that I have already done my seed order) that I could have a wall that changes colour through the seasons... Draba aizoides for spring, masses of Campanula muralis for the summer, then some sedum for the autumn... Thought about dotting some Erigeron compositus around to give some continuity.... But I guess I would need to have a light touch or I might end up with a spectacle that I wouldnt really wish to have....

And how to achieve it... That's the question... I understand that if roots are pruned, then the plant is encouraged to produce lots of small fibrous roots which will help to establish it quickly. If this is correct, then I might try it after stuffing the holes with some soil... And will try seeding a patch too, to see which method works best.

John, you have incredibly sharp eyes! How on earth could you make that out? I cant even see the ladder, even though I know it is there. It isn't a valerian though. It is a honeysuckle... A great thug of a plant which was growing unhappily in a pot when we moved here. After transplanting it grew away like mad and I have to cut it back severely every year to keep it in check.

[John85]

We are not talking about the same plant.
I had a look at your others pictures and between the one of the stone with the inscription:let me rise as larks..... and the one of the frame and the ladder there are several pictures of that plant

[SueStephens]

I've had a good look John, and I am not sure which one you mean...unless you mean the one with grey/green leaves which is Centaurea montana I think... already resident when we arrived.

[John85]

i send you a PM.