Gardening on a steep slope

Terracing allows for easier gardening after the initial cost and effort (but I think the steps are too steep to be comfortable)

Terracing allows for easier gardening after the initial cost and effort (but I think the steps are too steep to be comfortable)

I had a few days in Tauranga last week. It is always interesting for me, a country dweller, to stay in city suburbia. It reminds me that others garden in very different situations. In this case, I was staying with my sister who lives on a relatively steep hill and that certainly brings a whole new set of challenges for gardening.

If I was starting from scratch on a steep section, I would get wide steps in first and then start working around them in terms of the garden on the sides. Where space allows, wide steps look far more generous and remove much of the off-putting aspect of a steep slope.

Where space allows, wide steps look more generous and less onerous to climb

Where space allows, wide steps look more generous and less onerous to climb

There are rules for garden steps. The DIY home owner often makes the mistake of getting the tread width and riser depths wrong. The riser is the vertical piece and the general advice is that in a garden situation, it should not be more than about 15cm. To balance that, the tread (or flat part of the step) should be about 30cm. That is a gentler gradient than indoor house stairs. There is plenty of information around on this topic and it pays to take notice. The hand hewn steps in my sister’s garden were probably the other way around and very difficult they were to negotiate as a result.

If you decide to do a zigzag path crossing your section rather than steps, take the time to get the path almost level crossways. Most of us have two legs the same length. It is not at all comfortable to limp along a path that slopes sideways as well as wending its way up or down a bank. I say almost level. You want your path to shed water sideways rather than channelling it down the length so you need just a slight gradient across. Get the spirit level out.

Once the steps or paths are in, you can then decide what you are going to do with the sides. It is difficult on a steep slope. If you are a serious gardener, you will probably want to put in terraces. If you don’t, you are going to destabilise the slope every time you dig into it and the rain will wash the soil downhill. It is also physically uncomfortable to work perched on a steep angle.

Just remember that if you terrace and sow lawns, you need to make it easy to get the lawnmower down. If it is too difficult, you will keep putting off mowing the grass.

Weed mat is never a good look

Weed mat is never a good look

If you don’t want to tackle the effort and expense of terracing – the hard landscaping, retaining walls, finding topsoil to fill your terraced areas and the rest – you may choose to let nature take over your slope. One hopes not many of you will think it appropriate to clad your slope in ugly weedmat. That is a truly awful finish. In shaded areas, allowing ferns and mosses to colonise gives an attractive, natural look over time.

In sunny areas, you will need to give a helping hand. Whatever your opinion of agapanthus, it does a great job of retaining clay banks with the bonus of summer flowers. Alternatively, there are a range of sedums and sempervivens that you can plant and leave to smother a dry, sunny bank. Or you can establish our native iceplant (horokaka or Disphyma australe) which evolved to cope with these types of conditions. Renga renga lilies (arthropdium) prefer a little shade but will tolerate full sun and will grow in inhospitable soils.

A bare bank will erode so you need to stabilise it with something.

Professionals step fences to get them down slopes

Professionals step fences to get them down slopes

I would also observe that fences can define your station in life. A DIY fence often follows the lie of the land, undulating its way down the hill. A professional fence steps its way down. That is all on that matter.

The DIY fence is often obvious by its undulating line, following the contours

The DIY fence is often obvious by its undulating line, following the contours

I admit that I leaned on the decking railing at my sister’s house and looked at her steep section which runs down to a native bush reserve and then an estuary. I looked at my sister. Confine her gardening to the flatter, more accessible areas immediately by the house, I suggested, and let the lower slopes revert to bush. She will keep her lovely outlook without having to do major construction and continual garden maintenance on a difficult site. I think it likely she will heed my advice.

First published in the Waikato Times and reprinted here with their permission.

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