Start with the soil and the light

Before you buy a single plant, spend an afternoon working out what your border actually offers. A low-maintenance border is not an unplanned one; it is a border where you have matched your choices to the conditions so precisely that the plants need almost nothing from you. Two things matter more than anything else: how much sun the spot receives and how the soil behaves.

Watch the border across a full day. Note whether it gets six or more hours of direct sun, a few hours of dappled light, or only bright shade. Be honest, because a sun-loving lavender planted in shade will sulk, sprawl and need replacing within a year.

Next, test the drainage. Dig a hole about 30cm deep and wide, fill it with water, and see how long it takes to empty. If it drains within an hour or two, your soil is free-draining. If it sits there for half a day, you have clay or compaction on your hands, and you should either improve it with grit and compost or choose plants that tolerate damp roots.

• Sunny and free-draining: lavender, rosemary, salvia, sedum, hardy cistus, stipa grasses
• Sunny and clay-heavy: hardy geranium, echinacea, helenium, astrantia, cornus and viburnum shrubs
• Shade with reasonable moisture: epimedium, hellebore, ferns, hardy geranium, skimmia, sarcococca
• Dry shade: the trickiest spot, so stick with tough evergreens such as mahonia, liriope and tough ferns

Choose plants that earn their place

The plants that make a border easy are the ones that look after themselves. When you are browsing, ask one question of every plant: what does this do in the twelve months when it is not in flower? A good shrub gives you structure, foliage colour or scent for most of the year and flowering as a bonus.

Include a backbone of evergreen or semi-evergreen shrubs, ideally one for every two or three metres of border. Choisya, hebe, euonymus and sarcococca are all unfussy and give you a green frame that hides the untidy gaps. Around them, use long-lived perennials that do not need staking, dividing every year or deadheading every week.

Avoid anything labelled as needing rich soil, constant moisture or protection from wind unless you are prepared to provide it. Be equally wary of very fast spreaders such as some of the more thuggish hardy geraniums and golden marjoram, which will need controlling twice a year rather than once.

Group by water needs, not by colour

This is the single most useful design decision you can make. Instead of mixing thirsty plants with drought-tolerant ones, arrange the border in zones so that each area can be watered on the same schedule. The usual pattern works well: put the plants that want the most moisture near the house, the tap or the patio, where you are most likely to notice them and where a hose reaches easily. Move steadily towards the driest, most sun-baked end with plants that shrug off drought.

Three zones are plenty for a typical garden:

• Zone one, thirsty: astilbe, rodgersia, ligularia, hostas and moisture-loving ferns
• Zone two, average: most hardy perennials, including geraniums, astrantia and nepeta
• Zone three, drought-tolerant: lavender, rosemary, thyme, sedum, cistus, euphorbia and ornamental grasses

Within each zone, plant in generous groups of three, five or seven of the same variety rather than ones and twos. Grouping looks more deliberate, is far quicker to plant, and means each root runs into a network of the same moisture requirements.

Use layers and ground cover to smother weeds

Bare soil is an invitation to weeds, and weeding is the chore most low-maintenance gardeners want to eliminate. The answer is to fill the ground completely with plants, in layers, so that light never reaches the soil surface.

Start with a low carpet of ground cover: hardy geraniums, alchemilla, tiarella, epimedium, lamium and low sedums all knit together within a couple of seasons. Above that, add mid-height perennials and small shrubs, then a few taller shrubs or grasses at the back to give the border a horizon.

Allow plants to touch. A border where every plant stands alone with bare earth around it will need weeding fortnightly through the summer. A border that closes ranks by midsummer needs almost none.

Mulch properly and water sensibly

Once your plants are in, spread a mulch of well-rotted bark or compost to a depth of about 7cm across the whole border, keeping it clear of stems and crowns. This does three jobs at once: it suppresses weed seedlings, it slows evaporation from the soil, and it feeds the soil as it breaks down. Top it up each spring when the soil is damp and warm.

For watering, install a soaker hose or a simple drip line on a timer if you can. Delivering water slowly at root level is far more effective than standing with a can, and it encourages deep roots that survive dry spells. Water newly planted borders thoroughly for their first summer and then, honestly, aim to stop.

Autumn is the best time to plant, giving roots a whole mild season to settle in before the heat of summer arrives. Space plants according to their eventual spread rather than their pot size, and resist the urge to cram them in.

A light-touch rhythm through the year

Low maintenance does not mean no maintenance, just less of it and at sensible times. In spring, cut back last year's growth, top up the mulch and re-plant any gaps. In early summer, do one weeding pass so the border closes up cleanly. In autumn, leave stems and seedheads standing for the birds and for winter structure, then cut back the lot in late winter or early spring.

That is roughly two solid days of work a year. Everything else is just wandering out with a cup of tea and enjoying the fact that the border is quietly looking after itself.