Growbag Blog

How should Caroline tackle her sloping garden?

A flat garden, like having straight hair, would be a blessing according to Caroline. What do you think?

If you feel that you too could create a Sissinghurst or Dixter if only your garden wasn’t at a 45 degree angle or plagued by episodes of mounds and dips, you’re about to be inspired. You’ll realise that your slopes are indeed a gift and those iconic gardens have simply learned the tricks of using them to advantage.


Like a pea on a drum my house here in Scotland sits on 700 tonnes of in-fill. If you’ve ever built a house on a sloping site you’ll know that when the lorries roll up, the diggers get going and money is literally evaporating before your eyes, plans for your Italianate courtyard garden slip away at a similar rate.

However I’ve seen some wonderful sloping gardens such as Branklyn in Perth and Inverewe at Gairloch.  I’ve noted that by creating terraces, steps and paths (NB you need the latter for your wheelbarrow and lawnmower), you can create a charming garden journey peppered with planting pockets that distract you from the mild angina attack you may be experiencing as you ascend.

Tackling the issue head-on, I’ve now got a network of paths and steps and I’m starting to plant up some shrubs to create a bit of structure (and cut down on that vertical strimming) but ‘free-draining’ is an understatement at the top of my vertiginous slopes. Water just tumbles down the surface to the bottom. Not one to give up (at least not immediately) I’ve created dips just above each shrub – in effect ‘wells’ to allow water to dwell and hopefully drain into the roots below. I’ve also cut off squash bottles and plunged them into the soil above a plant into which I tip a litre or so of water, and I underpin my precious plants with a large brick or stone to create a crude dam below.

How hard can it be? I asked myself. Extremely hard was the answer. Don’t attempt to create steps yourself unless you’re Mensa material. It’s significantly harder than playing tennis as it turns out.

So far, so good although but going back to the steps – my attempts at creating them would have made Brunel weep. Like tennis it’s much more difficult than it looks involving physics and geometry. Speaking of which my clever sisters are about to tell us what to actually plant on these slopes….


Yes, well, there is no doubt that Caroline is the sister with the most experience is this department – parts of her garden would be more suited to crampons  and ibexes than robotic lawnmowers and fragrant nooks.  I do think she has the right idea by dividing up with flat paths – in effect, ‘terracing’ it somewhat.  Frankly, you have to give yourself some way of getting ‘at’ the garden in the first place!

I do have some thoughts about what she should plant on her exposed and sloping site (will she listen? Not a chance). While water flowing downwards and therefore away from the plant roots might be a problem in some gardens, I don’t think that’s going to much of an issue in her Highland hideaway, to be honest….I think it’s going to be more critical  to stop the topsoil being washed away by planting things whose fibrous roots will hold the earth steady even in heavy rain.  

The fibrous roots of ferns will really help to hold a bank together

Plants like ferns, Perovskia (Russian sage) Vinca (periwinkle) and Lamium (deadnettle) would do this job for her, and provide an attractive and robust ground cover to shelter and protect other plants such as Hemerocallis (daylilies), violas, Phlox or Rudbeckia.

Daylilies will grow well on a sunny slope

And what about the height of the plants? Putting taller plants at the bottom of the slope and short ground-huggers at the top would be the logical approach.  If the site catches a lot of wind, taller plants will get flattened and look a right mess, though.  In that case, it’s best to look for lower plants that have a creeping or weeping habit – I’m thinking of lovely things like Ceonothus thyrsiflorus var. repens, Euonymus fortunei “Harlequin’, ornamental grasses of all kinds,  and Pachysandra. Cytisus praecox (Warminster broom) can look totally wonderful dripping down a slope, for instance.

Cytisus (broom) looks fabulous tumbling down a bank


I’ll tell her not to plant the ground-cover roses which are so often recommended for a sloping garden, however – they are a total NIGHTMARE to weed!


My sisters like to portray my approach to horticulture as old-fashioned and nerdy , but my suggestion for Caroline’s slopes is much more progressive and actually much simpler and cheaper. I would like her to have a shot at a pictorial meadow.

Developed by one of my gardening heroes Nigel Dunnet (he of the Olympic prairie plantings in Lee Park) a pictorial meadow is based on the principle of dense plantings of either annual or perennial flowers, generally a combination of the best native and non-native species, that give the most bang for your buck in terms of colour, nectar and bird seeds over the following winter.

Pictorial meadow
The dense planting of annuals smothers out pesky weeds giving wall to wall colour and nectar. A typical mix will include poppies, cornflowers, cosmos, tickseed, sunflowers and toadflax.

Caroline should go for an annual mix to start with. You just sow them in spring (April is best) on a clear area of soil and tread them in. Pictorial meadows are sown at a much higher seed rate than conventional ones so the density of seedlings overpowers most weeds – our feature picture this week is a great example of this. After this there is very little maintenance required at all until the next spring when the area is cleared and prepared for the next summers meadow. A properly thought-out seed mix will give a succession of flowering ‘explosions’ from early summer through to autumn as each of the species hits their zenith.

And the great thing is there’s no need to have such a low soil fertility as is normally required by a purely native wildflower meadow (because many of the species are native weeds of arable fields such as poppies and cornflowers which are adapted to richer soils). Before Caroline starts bleating about the seeds being washed down her slopes, this doesn’t seem to have been a problem on the steep sides of the moat at the Tower of London where the Superbloom planting consists of just such an annual pictorial meadow – I’d love to see it, have any of you been?

Pictorial meadow at Tower of London
Superbloom at the Tower of London moat is just hitting its stride – well worth a visit I should think

To test my proposal out I encouraged Caroline to download the Tower Superbloom App which can give you an augmented reality experience of what your patch of ground might look like when sown as a pictorial meadow and here is the result……

NB Here are the details of the ‘Superbloom’ event at the Tower of London and if you want to create a virtual pictorial meadow in your own garden you can download the Tower Superbloom App.

If you want to have a shot at creating one for real (I’m certainly going to have a bash next spring) head to the Pictorial Meadows website.

Another NB Louises plant of the month is a superbloom all of its own, a climber with a two tone flower in the best possible taste. Click on the box below to find out what it is.

More NB If you’re not already a subscriber and you’d like a bit more gardening chitchat from the3growbags, please type your email address here and we’ll send you a new post every Saturday morning.

By the3growbags

We're three sisters who love gardening, plants and even the science of horticulture but we're not all experts. We'd love everyone even remotely interested in their gardens to be part of our blogsite.

4 replies on “How should Caroline tackle her sloping garden?”

Managed to see the Superbloom on Friday evening. It really is lovely and you can tell that the flowering is going to go on and on with some areas yet to get going while other parts are already a mass of colour. It is a great idea and I hope it is going to be around for a while.

Oh Allison you lucky thing – it’s Laura here and it’s lovely to hear from you. I’m very envious of your visit to the Tower Superbloom – I’ve heard that it’s just hitting its stride after a slow start due to the vagaries of our cold spring weather this year. I think you also spotted me up a ladder in the latest RHS Garden magazine on one of Henchman’s splendid ladders didn’t you!! Thanks for being such a supportive follower of our various activities, we should try to meet up soon – I recently went on a visit to Denmans gardens down your way and was really impressed by their renovation – well worth a second visit if you fancy it ?? Best wishes Laura

Hi Caroline, I too have a 45° slope ending in a retaining wall. I also live in Scotland, in Sutherland so we have a good variety of weather thrown at us ! The slope was created, many years ago before we lived here, by tipping rubble and “soil” so it’s not the best….it was a mess ! Full of horsetail and good variety of other weeds !! My answer was to cover the whole slope with heavy duty weed resistant matting and then plant in holes in the matting…it seems to be working well, I still get horsetail but, in time I’m hoping the plants will cover the matting and fight back ! I’ve planted cranesbill geraniums ( several varieties ), blue grasses, Phlox Sublata ( lots of these for colour ), pink wild strawberries, Hosta….in fact anything I thought would colonise and spread ! It’s been a full year now and it’s taking shape ( photos are available ! ). I have to say that the idea was mine but I had a wonderful lady gardener who risked life and limb to scramble down the slope, she was amazing !! Good luck with your slope, I hope it goes well !

Diane how absolutely fabulous to read your comment. Caroline here and I too, lived in North-west Sutherland for a while 79-82 to be precise – shows you how ancient all the Growbags are! From your description you can definitely ‘feel my pain’ as it were. I have the same ‘builders rubble’ ground at a terrible angle. You’ve done exactly the right thing by the sound of it and I rather wish I’d done the same on my steep slopes. Strimming them is a nightmare and I can generally only descend them on my backside so I sympathise with your lady gardener friend. I wish I’d taken your advice BEFORE planting my shrubs, I don’t think it would work putting matting on in retrospect. The scent from Azalea Luteum always reminds me of Sutherland – such a magical part of the world. Good luck with your fantastic project Diane, (which sounds as if it’s coming on very well) and thank you so much for bonding over our sloping issues! XX

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