Culinary herbs are easy to grow as long as you treat them like the varied plants they are
Using fresh herbs for cooking is always a joy, the small pots from the supermarkets have a limited life on the kitchen windowsill and work out quite expensive. Growing some in your garden makes them always available with little effort and in much greater quantities.
From a gardening perspective, the term "Culinary herb" is an artificial category for a whole group of completely different types of plants, some are more vigorous than others, some are hardy or half hardy annuals, some are hardy perennials while others are shrubs. This means that they should each be considered on their own merits when growing them rather than treating them all in the same way because they are culinary herbs. What they do have in common however is that they mostly like to be grown in full sun which enables them to develop more of the flavours that we are growing them for in the first place.
Herbs to be used for cooking are best planted into your garden soil. You often see them presented in mixed containers, sometimes split into separate sections which look very attractive though they don't stay like this for very long because different herbs grow to different sizes at different speeds. These herb collections are better seen as more akin to a long lived bunch of flowers, they will soon grow out of balance and are only successful in the short term. Herbs can be successfully grown as one variety per pot but be aware that once you start cutting them for use, they will look quite tatty. I have a mainly-herb area right underneath the kitchen window, but also have herbs in the vegetable garden and in the ornamental front garden.
These are what work in my garden in East Anglia, they are also herbs I use regularly. There are many others available some of which I've tried and didn't like my conditions, others that did but I never used so I pulled them up. One thing I found is that if I grow a herb I like and it grows well, then I end up using it far more, I'd never made tabbouleh myself until I had a glut of flat leaf parsley, now there is no such thing as a glut of flat leaf parsley.
Mint - herbaceous perennial, 45cm tall, 45cm spread though can go further if you let them.
A must have for its uses and ease of growth, best grown from plants as it is not so easy from seed.
Mint has a habit of spreading into every nook and cranny once it gets going - IF it likes your conditions, if it doesn't it can be quite sulky. The customary advice is to plant it in a bottomless bucket sunk into the ground. If you do this leave the bucket rim sticking out of the ground by an inch or two.
Parsley - annual / biennial, 60cm spread, flower spikes 1-1.2m or more
Easily grown from seed, treat as an annual in spring-summer or sow in mid to late summer to grow through the winter in a cold greenhouse or conservatory, grows too big for a windowsill unless cut early.
Grow in the soil. If you don't have a vegetable patch, a sunny gap in the garden will do fine, maybe where spring flowering bulbs were. They can soon run to seed in hot summers, the seeds can also be very useful. If you aren't going to use the seeds, pull them up when they start to flower as they rarely produce many more leaves and get very tall and tatty.
Chives - herbaceous perennial, 30cm tall and wide.
Easily grown from seed it's almost a wonder they don't germinate in the packet. If you let a plant establish itself, you can divide it annually for ages, give them away and be everybody's mate. If the plant starts to look tired after a year or two throw away the old centre of the plant and replant the outsides. Pretty pink/purple flowers too. so even if you don't use them in cooking so much, they are a worthy garden border plant in their own right.
Oregano - herbaceous perennial, 45cm wide to about 30cm tall
Easy to grow and easy to propagate from seed, just put it in a sunny spot and ignore it until you want to pick it - always an admirable quality in a plant that you intend to cut bits off on a regular basis.
Later in the summer oregano produces masses of pretty pink flowers that are adored by bees and butterflies, so as far as I'm concerned it's a star plant. Good for the front of a herbaceous border.
Bay tree, bay laurel, sweet bay - evergreen shrub, to 7.5m+ if allowed, usually much smaller.
Buy as a young potted plant. A reasonably hardy shrub in all but the harshest of UK climates. They can grow large albeit quite slowly.
Can be successfully grown in large containers, often shaped or gently topiaried into pyramids, a standard ball or similar, they are less hardy in containers as the roots are more vulnerable to frosts. Best grown in the soil in a sunny or semi-sunny sheltered position.
Rosemary - evergreen woody perennial, 1-1.5m high and wide
Buy as a young plant in a pot or can be readily (if a bit slowly) propagated from cuttings if you know someone who has one. A versatile herb that is great with roast things especially lamb, potatoes. carrots, parsnips etc.
It is a useful garden plant in its own right, evergreen with attractive flowers that bees love. It can be pruned to keep its shape, whether you want it to spread or become upright. Can be usefully grown in containers if you wish to do that though ultimately gets rather informal - tatty if you're unkind.
Sage - evergreen woody perennial, up 75cm high, 2m spread if you let it
Easily propagated from seed as the plain and most highly flavoured native species. There are some more ornamental cultivars that are less strongly flavoured that can be bought as potted plants or propagated from cuttings if you know someone who has a plant.
Grows to a dense mound of foliage about 60cm (2 feet) tall and a little more wide. If you're going to use lots go for the species and keep it by the vegetable patch, if you're going to use it for more occasionally one of the cultivars in the ornamental garden will be fine.
Thyme - evergreen woody perennial, 20cm tall, spread 50cm
Easily grown from seed, there are many ornamental varieties though they are slower growing and will take a long time to recover if harvested for cookery, so for culinary reasons go for the green species version.
Thyme is another worthy garden plant in its own right with edibility as a bonus and pretty bee-magnet flowers. Often recommended to be grown in pots as they don't over winter well otherwise, mine overwinter MUCH better in the ground than in pots.
Basil - half hardy annual
Grow from seed or more easily split a pot from the supermarket (see below). Difficult to any worthwhile extent outdoors in the UK, It likes a temperature, degree of protection and level of sunlight that is just not readily found. It won't grow well enough outdoors to give enough for culinary use, maybe in the south with protection from wind and a sunny warm position you may have some success. A greenhouse or conservatory is ideal or a sunny kitchen windowsill during the brighter months, there's not enough light in winter to keep it going.
When gathering herbs, treat it like pruning the plant. You'd never prune by removing leaves and leaving a naked stem so apply the same principle to your herbs and you'll be rewarded with more and more leaves to pick and better looking plants.
Depending on the variety, try to pick whole or part stems that you then strip of leaves. Cut the stem at a point where there are emerging side-shoots. Basil has side shoots at leaf junctions and so tolerates leaf stripping to some degree, whereas mint doesn't and responds better to having whole stems cut at about ground level.
Herbs require energy to produce the substances that give them their tastes and flavours and that energy comes from sunlight. So herbs generally do better in full sun as they have more spare energy to go into the production of their delicious flavours and produce more of them. It does mean that you'll have to keep an eye on watering as the soft leafy types in particular can dry out quickly in such positions.
Making the most of supermarket herbs
While growing things from seed can be a very cheap and easy way of getting lots of plants, you may not have the space, the inclination or the need for so many plants. Supermarket potted herbs are a relatively cheap and easy way to skip the part between seed and small plants. The pots that are sold for immediate use are of overgrown, over crowded plants that should have been pricked out long ago.
This doesn't matter if you're going to pick all of the leaves and throw the rest away, though with a little bit of effort it is possible to make a pot of herbs last for months on end and keep a fresh supply on the kitchen windowsill all summer for the price of one pot.
Here's one of my favourite herbs, basil, as bought for £1.25, there are around 20-30 individual plants each of which are very leggy. Split the roots and compost in three or four equal parts by pulling apart gently.
Take each of these mini clumps and place one into each of the corners of a new plant pot, fill in the gaps with potting compost. The end result is three or four pots of herbs with more space for the young plants than the original one. Water them well and place onto a sunny windowsill.
Leave for a week (longer if you can) beore you begin to pick them and pick first from the densest pot. When this has been decimated, leave it some time to recover and move onto the next densest which should have put a fair amount of growth on by now, then eventually move onto the last.
Water and feed as you would house plants. If you put the plants on a bright windowsill, you will have a good supply for months on end. Sunshine is good, but may be a bit too much for the whole day in mid-summer, open a window for ventilation and don't let them dry out too much. Many herbs do best in the sun, basil along with other Mediterranean types need full direct sun to develop the best flavor.