Stone walls

Red Valerian

Having planted my few hawthorn plants the other day to start a country hedge on a section of the boundary where the short dry stone wall has collapsed, I've since had a dry stone waller come over to give me an estimate for rebuilding the tall retaining stone wall that is holding up much soil on level two in my terraced garden. 

He is due to start working on it in a few days, which is good because once they 
start collapsing they deteriorate very fast.  He is only taking down about the top third or two as the base of the wall is fine, and he will be able to remove the roots of the brambles and ivy when it is dismantled.  As this was the part of the garden that was bothering me a lot, I'm feeling pleased that this work will start very soon.

I want to have some idea also of what plants to grow between the cracks, as this helps to knit the whole thing together and prevent other plants from colonizing the spaces between the stone.  Since I removed a lot of the ivy from another much taller mortared wall outside my back door, the red valerian has colonized it and now that is growing everywhere, as it does in many of the stone walls in the local area.  I laugh when I recall that red valerian was the first plant I bought at the very first plant fair I attended when I moved to this area - I needn't have bothered because they grow like weeds everywhere.  As do the forget-me-nots, a plant I love but still have to dispose of some as it spreads everywhere.

So I'm going to compile a list of possible plants, especially local ones but also alpines, at the bottom of this post sometime, adding to it when I think of another one i could try.  Stone walls are wonderful as they are constantly changing throughout the year, those that have plants growing in them that is, so it is good to have something in flower each season.  The waller guy suggested primula, campion and allysum for starters.  

I have various photos of stone walls in this local area, both with and without plants.  I thought I'd dig some of them out to post here.  I'd previously considered taking a course myself in stone walling as I'd like to see this tradition preserved, but my own retaining wall is a bit beyond my skills as it means going around corners and it is holding up a huge volume of earth.  I laughed when I looked on a website which described stone walling as a bit like doing a 3 dimensional jigsaw without the picture.  I did manage to rebuild the top part of a raised bed which was a mess and it still looks good a year later, except that the very end/corner wasn't really sound enough.  

This a favourite stone wall which I often walk past, on a main road on the way to the supermarket. Next 3 pics are same wall.

The following is a stone wall with primula in the local park.

And one topped with heather (I think) in someones garden







And here is a dry stone structure along a bicycle route, and I have no idea what its purpose is for.

The following are not dry stone but mortared stone walls, showing what can be done with shrubs.  I'm going to plant shrubs at the top of mine if I can find somewhere sunny enough to move the roses to once they are dormant.

And this wall I liked for the wall alone, while out walking.

And finally, this one gave me an idea as to what I can do with the concrete pillar by my front gate.  Decorate it with stones.

PLANT IDEAS FOR GROWING IN CRACKS IN DRY STONE WALLS


1.  Allysum  - white.  Likes lime
2.  Arabis caucasica /Rock Cress (perennial) - white flowers in April  
2.  Aubretia (evergreen trailing perennial)  - mauve
3.  Campanula carpatica (perennial)  - mauve, blue or white
4.  Irish Moss

And from the bbc website:

Planting such walls is great fun but there are some conditions. The selected plants should be small, non-vigorous specimens that won’t cover the wall spoiling the natural look of the stones. They need to be tolerant of drought conditions and a restricted rooting area.

Trailing plants work well but need to be well spaced otherwise they smother the lower plants. Avoid ivy varieties that will become invasive.

Small alpines are ideal and some such as Lewesia cotyledon with rosettes of leaves are best planted on their side as this prevents rain lying on and rotting the foliage.

Snails may be a serious pest as they love to hide in such walls and constant attention and baiting will be needed to deter them.

If the wall is being built then that is the time to insert the small plants along with as much soil as the crack or gap will hold. If the stone above the plant is sloped backwards then rain will trickle down to the roots of the plant.

For existing walls it is essential that the plants are simply rooted cuttings or seedlings that will establish and grow to fill the root zone available. Larger plants will sulk and probably die.

Don’t be tempted to use any of the multi-purpose composts. They will be prone to drying out without much chance of a good soaking. Use a sterilized soil without any fertilizer.

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While your wall plants are getting established, they will need regular watering using a fairly fine mist. Heavy sprays of water may dislodge the plants or even wash away the soil completely. Have some extra sheet sphagnum moss handy to stuff cracks if you notice the soil is washing out. After planting, a wall may need to be misted about three times a week for a month or so – less often if you get regular rain, more often during the heat of summer. Watch for signs of wilting plants and let that be your guide.