There are a variety of ways of achieving neat edges, depending on whether the grass runs up to a bed/border, or up to a wall, or up to a patio. Each has its own problems, and solutions, so I'll cover then in three sections:
Beds and borders need to have an edge, even in cottage style planting, otherwise they will always look scruffy and unkempt.
Firstly take an overall look at the shape - are the straight edges still straight? Are the curves regular, and "nice" to look at? Or do they waver in and out? Use pegs and string to check and adjust straight edges, or lay out a hosepipe to assign "nice" curves. Then cut the turf off to those lines - you can use a proper half-moon edger, or a small border spade to do it, just make sure you cut down vertically. After you have gone along the whole edge, go back and remove all the chopped-off bits of turf, which can often be useful for filling in any gaps in the newly defined edges, or to patch in any bald spots elsewhere in the lawn.
If you end up with a large pile of bits of unwanted turf, turn them into a loam stack: make a neat stack of the bits in alternating layers, green side up, then green side down. After a year or two, the heap will have turned into a freestanding stack of wonderful rich loam which can be used for potting, or can simply be spread on the beds as a combined mulch/soil improver.
Having re-shaped your edges, go round again with a hand trowel and ensure that you have a clear, sharp edge all the way round, flicking back the loose soil as you go - I am a big fan of what I call the "cliff and gutter" style of edging. That's where you cut a sharp vertical edge into the grass, 2-3" deep, and create a slight slope up into the bed or border. This gives a "gutter" which traps glass clippings and fallen leaves, making it quick and easy to maintain with long-handed edgers.
This cliff-and-gutter technique has the added advantage that couch grass - which is present in virtually all lawns - grows sideways, barely an inch or so under the surface. So if you cut a cliff edge about 2" deep, the couch grass roots find themselves waving about in mid-air and are chopped off every time you edge, thus preventing it from spreading into your beds or borders.
Clever stuff, eh? I am a professional, you know.
If you have very crumbly soil, or if you don't like having to keep recutting the edges, you can choose to install a permanent hard edging strip. Metal is clearly the best and most durable, it works well for straight lines or for curves, or for a mixture, but it is the most expensive to buy and install. Wood strips look very cottagey, but can only accommodate straight lines: they will also need to be properly installed with pegs at intervals, to which the boards are nailed or screwed, and they don't last forever. Finally, there are some rigid plastic edgings available now, one of which I had the fun of installing recently. I haven't finished writing up that little adventure yet, but when I do, I'll come back and add a link to it. Good quality plastic edgings can be very effective....
... but whatever you do, don't even try to use that hideous wavy plastic strip.
Yes, this stuff (left).
It never, ever goes in easily, it looks as though someone has been round your beds with a dough cutter, and within a short time it will have gone brittle in the sun and been smashed to pieces by your mower.
Please, just don't use it.
Right, that's beds covered, next are vertical edges.
2) Walls: (which includes log roll edging)
The problem here is that most mowers won't go quite up to the wall - or should I say, most mowers don't cut out to the edge of where the wheels go, so you always end up with an untidy fringe of uncut grass.
The answer is to insert a mowing strip: something laid flat at the base of the wall, projecting a couple of inches out, on which the wheels of the mower can run.
This can be stone setts, those nice red paviours, or good old ordinary bricks, set flat on the ground, frog (indent) down. Using the same colour material as the wall often looks neatest: on the other hand, a contrasting colour can look stylish. Whatever you use, butt them right up against the vertical wall, and ensure they are level with the grass. Being individually small, they have the advantage of being able to accommodate a certain amount of curvature, as well as making very sharp straight lines.
You can use "stone" in the sense of random bits of stone found in the garden, but if you have too many gaps, the grass will grow up between them and spoil the effect.
Here's a simple example pinched off the internet: a low brick wall, with a line of what looks like granite setts at the base.
It's just enough to let the mower's wheels run over the edging, so all the grass gets cut. No more long-handled edgers! No more strimming! No more having to get the shears out and go down on hands and knees.... and of course, if you are having a wall built, have a mowing strip built at the same time.
It has the added advantage that most walls are built on some sort of foundation which often extends a couple of inches either side of the wall to spread the load, and this often prevents the grass from growing properly, so you get a tatty strip of half-dead grass and bare weedy patches, combined with some areas of long scruffy grass. Not nice!
3) Finally, patios: in a way, they are one big mowing strip so they should not be a problem, but in many gardens they present an untidy, uneven edge.
The first job is to go along the edge with a daisy grubber, or a small hand tool and pull out any grass that is finding its way between the individual slabs or bricks of the patio.
Now look at the grass in relation to the patio - are they the same height? If the grass is higher than the patio, get out (or borrow) the roller, and squash it down until they are level. If the grass is a little lower, that's not normally a problem: if you wish, you can raise the lawn by either lifting the edges and tucking extra soil underneath (hard work and quite finicky to get correct) or you can sprinkle soil or compost lightly over the area every couple of weeks for the next several months, until it has risen to the right height. This looks a bit odd for several months, but is cheap and easy to do.
Next, go all along the edge again, making a very small channel between the patio and the grass: it needs to be just big enough for the long-handled edging shears to get in, so about an inch deep and maybe half an inch wide should do it. You might need to scoop out a little strip of soil to achieve this.
Once you've cleared it, take the edging shears, slot them into the channel, and trim the grass - just to check that you have cleared a channel correctly.
If the patio is crazy-paving with an uneven edge, then you are going to struggle to keep it neat: the options are to either take the time to lay a formal edge, mortaring in any gaps, or to accept that you will have to cut a straight edged channel right the way across it, leaving some earth-filled gaps on the patio side which will have to be weeded by hand every so often.
Most gardens have a combination of these three lawn edges - beds, walls/vertical, and patios - and it is well worth spending some time to sort them out, as it makes such an improvement to the general appearance of the garden, quite apart from the amount of time it saves you each time you cut the lawn.
The final advantage is that sometimes, if you don't have time to cut the whole lawn, just clipping the edges can make it look neat and kempt, in a fraction of the time it would take to mow it.
Did you enjoy this article? Did you find it useful? Would you like me to answer your own, personal, gardening question? Become a Patron - just click here - and support me! Or use the Donate button for a one-off donation. If just 10% of my visitors gave me a pound a month, I'd be able to spend a lot more time answering all the questions!!