I thought I'd start a thread on this as it was a theme running through the marvellous Landscape Conference last week. Claudia West and others challenged us to plant up the ground layer rather than using mulch under our perennials to bring in additional biodiversity, cool the soil and to avoid the mulch making the soil too rich (resulting in some plants taking over and diversity being lost). I have had the excellent book Claudia wrote with Thomas Rainer (Planting in a Post-Wild World) for a while - so I've been experimenting with this and it's challnging to find suiitable ground layer plants. They must be enough of a competitor to cover the ground (but not smother the emerging perennials, grasses and bulbs; deal with a the full light range (full sun in winter and early spring followed by full shade in late spring and summer when the perennials and grasses overwhelm) and must in my case also be dry tolerant (or dormant in summer).
So here are some initial thoughts (I am in Oakleigh East in Mebourne - approx 600mm annual rainfall, wet winters, dry summers when I only water 3-4 times deeply, about 3 frosts per year, soil is sandy loam to sandy clay loam on a yelow clay base)......
Ajuga reptans - may work for some, but I find the dry kills most of it off in summer
Banksia Blechnifolia - I'm keen to try this - you can see it at Burnley gardens coping with pretty much complete light range - and the architectural foliage is a bonus if you like it - as long as it's repeated enough it should look OK -has anyone tried it under perennials / grasses?
Bergenia cordifolia - good for the edges - would it surve full shade further back in the border? I'm not sure- does anyone know?
Campanula poscharskyana - this one does well for me but it's never as lush as I'd like for the green mulch purpose - it survives being swamped by the perennials and grasses though.
Clivia minata - we all know this one and once established it provides a good dense ground cover and survives being overshadowed - the issue for me is that it is so good at smothering that it can't be planted enmass with perennials as it out competes them - so only really good in clumps or under subshrubs and shrubs in my view - but maybe others have had different experiences.
Cyclamen hederifolium - this does well for me - dormant in summer and pops up nicely to flowerr provided I cut down the perennials over it early enough (thats the problem - sometimes I can't bring myself to do it that early).
Dichondra repens - this is a good doer as we all know - I confess I have not used it as I thought it might not be sufficenienty dry tolerant (I'm probably wrong?) - what about 'Silver Falls' fully imersed in the border as Michael was wondering in the conference workshop? Does it survive?
Epimedium grandiflorum 'Rubrum' - this is one I'm keen to try - Andrew Laidlaw has it planted at the Bot gardens and it is making a dense ground cover with that lovely burgundy tinged foliage - it shoud theoretically cope with a wide light range - has anyone tried it?
Helliborus - what's not to like here - glossy green architecturasl foliage, winter flowers and a summer dormancy - these do well under perennials for me
Lamium galebdolon - this one is a winner for me - the silverly leaves are a bonus and it will grown in the dark pretty much. Be careful though - it's pretty weedy - so you have to be prepared for it to spread and root everywhere or to contain it...
Viola hederacea - This does well for me (too well actually) in any area that is always in semi shade to full shade (it will grown in the dark) - but if it gets the sun on it at he front of the border when it is dry in summer it burns and looks awful. Where it does well it is such an excellent competitor that it will smother a lot of perennials. I find Anemone x hybrida does well with it in a semi shades spot and I ad diversity with shurbs and bulbs...
Michael suggested at the conference that some other violets may be suitable for the ground plane - what have people had success with?
And what about smaller grasses - there must be some that would work?
Thanks in advance to all those I hope will respond.
Here are a couple that work for me - I'd love it if others would add to the list what works in your experience (and if you could indicate your location and climate please).
The Tricky Ground Layer - What Plants Do Well?