NOTES FROM MY garden

Alexandra Campbell investigates the challenges of planting on a slope.

SLOPING garden advice tends to be all about either “mat-forming” plants or plants with deep tap roots. But my friends, Richard and Lesley, grow all the same plants as those of us with flat gardens.

Their steeply sloping herbaceous border is full of roses, euphorbia, lilies, cannas, dahlias and persicaria.

When I asked them about mat-forming plants, they looked blank.

However, Lesley does say that if you’re gardening on a slope, you need to think differently. You can’t just go on pretending the slope isn’t there.

I have a slope of about 12 inches in one part of my garden, and I’d agree with her.

If I try to wedge a plant in there without thinking about how I plant it, it dies because the water runs off.

The first thing to remember, Lesley says, is that you can see a sloping border or a sloping area from more angles than you see a flat one.

Potentially, you could see a border from the front, back, two sides, looking downwards and looking upwards.

That means that the traditional “tallest at the back, smallest at the front” arrangement of plants often doesn’t work.

“Sometimes you’ve got to be brave and put a really tall plant at the front,” Lesley says.

However, the extra height going up the slope also means that you can still see shorter plants in the middle.

When Lesley started out, she did place smaller plants in the front, and she thinks it looked as if the border was slipping down the hill!

There are two key things to do if you want your plants to grow well on a slope – mulching and knowing how to plant on a slope.

Firstly, Lesley suggests covering the soil with a coarse mulch, such as bark.

This allows water to seep into the soil and prevents it from rushing down the hill.

If she applies garden compost or well-rotted manure, she would add the

coarser mulch on top.

Mulch also breaks down to feed the soil and it improves its condition, making it easier for water to be absorbed.

Secondly, when Lesley plants, she makes a mini terrace by digging a hole that’s deeper at the back than the front.

This holds water better, and she often also wedges a rock, brick or slate in front of the plant to hold water and soil in position until the roots get established.

It also helps to water quite slowly, so there’s more chance for water to sink in.

Staking is also more important on a slope than on the flat, she says.

Shady slopes are quite easy, because shade-loving plants don’t lean out towards the sun, but sun-loving plants can lean on a sunny slope even if the light is good.

Lesley uses a range of different plant supports, such as hoops, homemade twig supports and single shepherd’s crook stakes. She puts most of them in as soon as the plants emerge in spring. The slope looks like an industrial wasteland for a few weeks, but soon the plant foliage grows and covers up the supports.

It’s also very important to work out how and where the sun falls on the slope. Rather than thinking which plants are best for planting on a slope, you need to think about which plants are right for that amount of sun, and which ones grow best in your soil and climate. No need for mat-forming anything – whatever that means.

• Visit Alexandra’s blog online at themiddlesizedgarden.co.uk.