Shallow rooting plants for a border, suggestions please.

soulboy

As well as my own garden I help a couple of my neighbours with theirs. I am just about to finish the creation of a wide and quite long border in one of them.

The problem is that the topsoil was very thin with a layer of hardcore underneath, which I don't have the time or resources to remove. I did remove all the topsoil and sieved it to remove all the stones and removed a little of the hardcore. I've now started to backfill with that soil and I will add compost to finish.

When it's done I would imagine that the depth will be about 8-12", 20-30cm.

I know some plants such as violas and aquilegia will be fine but I would like to hear what flowering plants you all think would be successful in these conditions, including small shrubs.

The border gets full sun for an hour or two in the morning and most of the afternoon.

B3

Californian poppies

Bijdezee

Sounds ideal for a lot of alpines and rockery plants. 

soulboy

Thank you both for your suggestions.

Loxley

A lot of drought-tolerant perennials such as Sedums, that prefer well drained soils, should flourish. Small shrubs could include lavenders, Perovskia, and Caryopteris etc which enjoy dry lean soil.

Nollie

Small shrubs with fibrous roots, rather than tap roots, would be ok... like Berberis - some never get to more than 30-40cm high, The berberis ‘Rocket’ types are upright varieties, gets to a metre or so and don't need much soil depth. Euphorbias can make good, large shrubs, Wulfeneii is very shallow rooting, I heard, but most would be fine. Anything ‘Mediterranean’ - santolina, salvia, agastache etc. seem to cope with poor conditions better.

I had a similar problem with 20cm over a buried plastic pipe, didn't want anything too deep-rooting or that would pierce the pipe with a big strong taproot. Look for anything that likes a well-drained soil. Finding out which plants were shallow rooting was a bit of a nightmare as this info is rarely given in plant descriptions. I resorted to emptying plants from their pots in garden centres to have a nose...

Loxley

Yes E. Wulfenii would be ideal. Plants will root into the hardcore; the shallow rootedness isn't the issue so much as the ability to cope with poor dry soil. In fact some plants send down tap roots as a way of dealing with such conditions: https://www.bethchatto.co.uk/gardens/our-blog/garden-news/how-the-gardens-are-coping-in-these-extreme-conditions.htm

hogweed

Have a look at Beth Chatto's book 'The Gravel Garden' I think it's called. She built it in a former  car park so doubt if she had a lot of top soil there. 

Lizzie27

I would just add that if you are doing it for a neighbour and planting euphorbia, make sure you tell them to wear gloves when cutting the stems, as the sap is an irritant to some. Also berberis can be very prickly.

Nollie

Oh and on the shrub front, Nandina Domestica and cultivars such as Obsession, Fire Power etc, seem to survive on nothing, are evergreen and have good leaf and berry colour.

soulboy

Thanks a lot everyone for all your suggestions and advice. I should have been more specific in my question as the border is going to be cottage garden/herbaceous.

So that rules out sedums etc, but the advice on shrubs and plants such as lavender and salvia are very useful. She is also limited as to how much she can spend as she's a single working mother. So that rules out things like a rockery.

I'll definitely be putting in some California poppies and sunflowers, as well as foxgloves. I'll also sow some wildflower seeds and see what thrives. I have some salvia in my garden so I'll take some cuttings from that.