A soil can be dry because it is light and gritty or stony and hence well drained, and in this situation addition of manure and compost can do much to improve the situation by aiding water retention. If, however the soil is dry because of nearby trees, then you will probably have to cope by judicious planting unless you want to remove some trees. Mulching is a great way of reducing evaporation of water, but will do little to slow drainage.
Useful trees for this type of situation are acacias and many of the conifers, especially juniper, Lawson's Cypress, and many pines.
Coming down in size to the larger shrubs try olearia macrodonta, eleagnus, callistemon, and abelias. Medium to small sized shrubs would include santolina, hebes, lavenders, nandina, perovskia and osmanthus.
Flowers seem to tolerate dry conditions much better, possibly, being smaller, they require less water than the larger shrubs and trees. So don't avoid anything that you would really like to grow, you can always water a bit at the driest of times. However, the following are perhaps more suited than most to drought. Acanthus and crambe cordifolia, always a spectacular candidates, allium, alstromeria, cistus, euphorbias, echinops, lychnis, gypsophilia, nepeta, gladiolus, salvia, nigella, with its interesting seed heads in autumn, nicotiana (evening perfume), helichrysum, dianthus. There are many more!
Climbers are not so easy, concentrate on jasmine and passion flowers, and try solanum and campsis. These respond especially well to mulching.
For real inspiration do visit Beth Chatto's garden in Essex. Her gravel garden is in one of the driest areas in the country and on an exceptionally free-draining soil and yet she never waters and the garden is always looking in peak condition.
Clay soil can be very hard to grow in unless it is broken up, but when it is it is one of the best. Firstly make sure there is not a pan below your topsoil by driving a 3 ft (1m) spike into a square yard of ground every 4 inches or so. If the markedly improves your drainage, you have a pan and you must break it up by digging through it and while you are doing this incorporate 4 ozs per square yard (85 gms per square meter) of garden lime. Also dig in as much compost and manure as you can, both these additions will help to prevent a pan reforming and will improve the structure of your clay soil. Even if there is no pan the compost and manure will be very beneficial, but use lime at the recommended rate for your particular pH.
Once you have reduced waterlogging to a low level, you will find your soil very fertile but it will be cold, so this means you should be planting 2-3 weeks later than if the soil were lighter.
Trees that generally thrive in clay soils include sorbus (especially the whitebeams), eucalyptus, birch, crab apples, oak, ash, willow and many conifers, especially junipers.
The best shrubs are possibly mahonia and viburnum for winter interest, weigela, roses, fuschias, euonymus, vinca and buddleia for the summer and berberis and hydrangea for autumn.
Most perennials will survive well enough, but the following would be amongst the best; geaniums, hellebores, persicarias, astrantia, anemone, sedums and for late season the asters and crocosmias.
Herbs Which to grow
Which herbs to you use most in the kitchen? Clearly these are the ones to grow. In our house the most commonly used are mint, parsley, chives, cilantro and basil and these are all grown just outside the back door.
However there are many others and if you have space it is well worth growing a wider range than just the bare essentials.
If you like chives, try garlic chives, which as the name suggests combines a hint or garlic flavour with that of the chive. Both varieties grow in much the same way.
Dill which grows up to 1 m tall is an annual which is good with fish, vegetables and especially useful for adding to pickling vinegar. It is the basis of the flavouring that was used in Gripe Water.
Basil, best known for complementing tomatoes and has some value in deterring flies, it is a medium height annual.
A couple of flavours you may wish to generate are lemon and aniseed. For lemon, try lemon balm (medium height perennial) or lemon verbena (a tall slightly tender perennial. For the aniseed flavour try fennel, there is a bronze fennel which is very decorative and is a perennial growing up to 1.5 m
Tarragon is a herb used in quantity by good cooks on the continent, either for spicing pickling vinegar or in sauces such as béarnaise or tartare. Sweet cicely has a sweet anise flavour as well as a very attractive foliage.
There are a number of varieties of mint make sure you grow either spearmint or apple mint which are the standard ones in cookery, others are interesting and worth growing if you have room, try ginger mint and chocolate mint for something really different.
Finally lets give a little thought to some edible flowers nasturtiums make an excellent colourful and slightly hot addition to a salad, marigolds and borage also add colour and flavour
Growing you own veg
One of the advantages of growing you own veg is to grow things you cannot buy or rarely see.
So here are a few you might like to try:
Jerusalem artichokes buy as tubers, the plants grow to 2 m high and have attractive
yellow flowers which you can cut in September. Dig up lots of tubers all winter. Boil, roast or slice and fry.
Globe artichoke - attractive enough plant for the flower border, large jagged
leaves. Boil unopened flower buds, and get tasty flesh from the
petal ends, and the choke. Do not try to eat the hairs on top of
Asparagus pea - grow like a pea, but they dont really need much support. Pick the winged pods when they are an inch or so long, they quickly get woody. Boil for few minutes or steam.
Cardoons - very similar plant to globe artichoke, so another candidate for the flower border. I n this case however, it is the blanched young stems that are eaten, boiled or roast.
Mexican tree spinach - tall leafy plant, young leaves are purple. Use leaves like spinach and collect the seeds when ripe. Sow the seeds in seed trays during winter and keep in greenhouse or on a windowsill and collect the young leaves as a winter salad
Salsify - a root, so grow just like you would a carrot. The root is eaten in autumn, boiled or roast. Sometimes called the vegetable oyster, maybe it tastes like an oyster???
Rainbow chard - very colourful stems and easy to grow. A definite candidate for the flower border. Eat leaves as spinach, stems also eaten boiled or fried.
Babbington leek - plant a bulb and leave it alone the first year. It will flower and produce a number of small bulbs on top of the flower which you use to increase your stock. In all but the warmest areas dig the bulb up at the end of September and keep in the greenhouse, planting out late in April. In the second year cut stems at ground level and they will re-grow. Use as leeks or as a garlicky flavouring