Ferns. Best mortar.

I have a retaining wall in my back garden with loads of ferns sprouting between the large stones. I really like this rustic look although I am considering getting the wall straightened out as over time it is looking pretty ramshackle. The wall is probably about 75 years old. One option is just to straighten the stones but for both strength and longevity I am thinking of having them mortared. If I go this route is there a mortar that is best suited for ferns to grow? From what I've briefly Googled, lime mortar may be the best option. Any advice is greatly appreciated. Thanks.

 

I think ferns growing in old walls are nice, but surely its something that happens over years and not something you can plant as such.

Yes lime mortar maybe better for encouraging ferns in the future but I dont think they will move into new mortar very quickly.

I'd be very wary of altering things if you like the ferns.

 

Would think Lime Motar being more porous would be better for letting plants grow around it, though we have small ferns growing around brickwoork using standard sand and cement.

However in both cases thats for motar thats set and been well weathered as the Lime will be more locked in.

Putting fresh motar around or near existing plants is likely to kill them, as we have found when cementing in fencing posts and nearby plants that were not in direct contact with the cement soon died or took a year or two the recover.