Why mixing edibles and ornamentals works so well

A border that feeds you and looks after itself is not a compromise. In a small garden it is the smartest use of space you can make. Chard has leaves as glossy and architectural as any bergenia, nasturtiums spill over edges with the generosity of a good trailing petunia, and a clump of chives in flower is a purple pompom worth planting for its own sake. Add thyme, sage and marjoram and you have a border that smells wonderful when you brush past it and gives you something for the pan every time you step outside.

The trick is to treat edible plants as design ingredients, not as crops in rows. Choose varieties for leaf colour, flower shape and habit as much as for flavour, then set them out with the same spacing and repetition you would use for any herbaceous planting. Get that right and nobody will read the border as a vegetable patch.

Plants that earn their place twice over

Some edibles are simply too good-looking to hide away. These are the ones I reach for first:

• Rainbow chard — crimson, gold and pink stems give vertical structure and colour from May to the first hard frost. Cut outer leaves only.
• Nasturtium — peppery leaves, edible flowers, and a scrambling habit that softens the front of a border. Choose a compact or variegated type in small spaces.
• Calendula — bright orange daisies over a long season. Petals brighten salads; the plants self-seed politely if you let a few flowerheads ripen.
• Borage — blue star flowers with a cucumber taste. It grows tall and floppy, so plant it where it can lean on something.
• Purple or curly kale — a ruffled, bronze-purple rosette that looks superb against gravel or dark foliage.
• Herbs — chives, flat-leaf parsley, golden marjoram, variegated sage, fennel with its feathery bronze haze, and rosemary for winter structure.
• Scented violas — small, cheerful and completely edible. A few plants will flower for months.

Keep mint in a sunk pot, or it will run through the whole border within two seasons. Dill and coriander are best sown in gaps as cut-and-come-again crops rather than given permanent positions, because they bolt quickly in heat.

A planting plan for a sunny border

Take a border about 2.5 metres long and 70 centimetres deep. In the back third, plant rosemary or sage at one end for year-round shape, then a group of three chard plants spaced 30 centimetres apart, and a fennel or borage at the other end. The middle band is for colour and cutting: calendula, chives, marjoram and a couple of parsley plants, set in loose drifts of three or five rather than singles. Along the front, let nasturtiums trail over the edge, with violas and a row of red-leaved lettuce tucked in between.

Repeat one or two plants along the length — chard at both ends, say, or chives in two separate clumps. Repetition is what makes a mixed border read as designed rather than assembled. Leave a few gaps for successional sowing of rocket, coriander and small salad leaves.

Design rules that stop it looking like a veg patch

Three rules do most of the work. First, vary the leaf shapes: fennel's feathers against chard's broad paddle against sage's soft grey oval. Contrast in texture reads as ornamental instantly. Second, hold a colour palette. I find that a base of blues, purples and soft greens — borage, chives, rosemary, sage — with hot orange calendula and nasturtium as accents looks deliberate and never muddled. Third, let some plants flower. Chives, thyme and marjoram are all far more beautiful in bloom, and the bees will thank you.

If you want a tidier look, edge the front with a low, tight line of parsley or violas and keep the middle looser. A mulch of gravel or dark bark makes edible plants look intentional and helps keep the leaves clean.

Keeping the border productive and looking good

Water deeply once or twice a week in dry spells rather than little and often — shallow watering makes chard and lettuce bolt. Feed leafy crops with a general liquid feed every fortnight, but go easy on herbs; too much richness makes them soft and tasteless. Pinch out flowering stems on basil and coriander to keep leaves coming.

Slugs are the main enemy of young seedlings. Plant slightly larger plants where you can, keep the surface dry around the tender stems, and go out with a torch after rain. Cut back spent flowerheads on calendula and nasturtium to keep blooms coming, and lift and replace tired lettuce every few weeks. A quick tidy at the end of summer, plus a scatter of hardy herbs, will carry the border through winter.

Harvesting without wrecking the display

Pick little and often, and always from the outside in. Snip the outer chard leaves at the base and the plant will keep producing from the centre. Take no more than a third of any herb clump at once, cutting above a pair of leaves so it regrows bushy. Gather nasturtium and viola flowers early in the day, and pinch calendula petals straight from the head. If a plant is looking scruffy, cut it back hard rather than pulling it out — most will reward you with fresh growth within a fortnight.