You know the sort of thing- there it is at the start of so many old gardening books. “For your garden choose an open sunny site with a gentle south facing slope and a deep rich loam….” Oh if only life was as simple. Few of us ever have the good fortune or large enough fortune to be able to choose a perfect site on which to make our ideal kitchen garden. Generally we take what we can get and have to make the best of it. But if we do have any choice at all which are the most important parameters -and what should we avoid at all costs?

In many ways it is far easier to make an ornamental garden than a productive plot. Most importantly it’s the range of plants; ornamentals can be found to suit almost each and every condition as long as at least some weeds will already grow there. Vegetables, herbs and fruits are far more limiting in their needs for soil, sun and moisture. They are the horticultural world’s Olympic athletes, bred and raised to give above average performance. An onion, carrot or cabbage as nature made them is a poor thing, it takes generations of selection -and much improved conditions to get them to perform adequately. So you could create an enticing flower garden in the bottom of a shady damp hollow -but in the same place few crops would survive or give a good harvest. Likewise barren windswept places could be improved with some attractive plantings but hardly any fruits or vegetables would thrive there.

Of course a good gardener can grow almost anything anywhere, but the effort required may be worth far more than the prize. There is the challenge, and much pleasure to be had triumphing against the odds. But for a less stressful and more easily productive time it’s only sensible to grow things that do well in the conditions nature already provides.

Most of us are forced to grow on the flat but given the choice a slope is better in several ways. Most importantly cold air runs off just like water. Provided it has a way out of the garden it will drain away keeping frost off for longer than in a garden where the cold air can pool. For this reason walled gardens on slopes should always have grills or grilled gates at the lower end. (Warm air rises and so there is a slight tendency for the high end to become hotter than the bottom but this is only pronounced if the slope is steep or the air confined; say in a polytunnel, as otherwise warm air rises vertically.)

A slope can also be warmer because of the way it is angled. If it faces towards the sun then more sunlight falls on every square foot than if it lies flat or slopes any other way. (In the UK a South slope gets the most sun but in Australia it’s the reverse) This effect is greatest use to us in winter when steep slopes are much better lit by the low sun than others. (Thus the similar value of tiered staging) And all barriers casting shade do so over a lesser area if the slope is steep and faces the sun.

So the sun comes up and shines on everyone- but not for long down in the bottom of valleys and never directly on a north facing slope in the UK. True the earliest and latest light in midsummer may just glance on a north slope but such a place will always be cooler and shadier than any other. And few of our vegetables do well in shade. True some of the various saladings, spinaches and leafy crops may enjoy the coolness of some light shade in midsummer but for the rest of the year a shady place is never a good choice for a vegetable plot -and especially not for the majority of herbs, though mint would survive. Some fruits may crop on a shady slope though they are likely to be late and not as sweet as those in full sun. The toughest pears, currants and bramble berries can crop on a shady slope but usually do better when given more sun. Obviously some can be trained upwards to catch more sunlight but then they increase the shade on those behind them. In hotter drier regions such as East Anglia, in dry thin soils, a few; blueberries, raspberries and Tayberries are happier on a cool north slope than when angled towards the sun. BUT if you have a south facing slope you will probably have some shady north facing walls or hedges to place these awkward few -and much better conditions everywhere else for everything else.

An East facing slope gets little benefit from afternoon sun but the cleaner air of morning often makes for brighter conditions than the dusty evening air so it often grows many crops better. But then these also risk more frost damage when the sun strikes their frozen parts and defrosts them too quickly. A West slope is shielded from the morning sun and so ought to be better for earlier frost prone crops but traditionally it is reckoned the worse! So a South facing slope is not just perfect and first choice, but given any choice it is the only one. Yet you do not want to be at the bottom of it as there all the cold air and flash floods will be at their worst. On the very top may also be unfavourable if it is windswept and bleak. From Roman times it has been reckoned to be best to set your garden below the brow of a south facing slope.

A slope does have drawbacks; the work is more tiring going up and down all day, rain and mulches can rush to the bottom leaving the topmost parts dry and bare. But the good old advice is quite right choose a south facing slope, and if you can’t have one it is probably better to be on the flat. After all you can always make raised and angled beds to create your own small South facing slopes.

You really do not want to be down in a declivity; cold damp air fills all low lying places making crops late and almost everything there will be prone to moulds and rots. The only exception is where there is a still lower place to take away the problem so low spots beside rivers are better favoured as these ‘suck away’ the cold air. But rivers also create a dampness of their own with a high water table which may be excellent for salads, summer crops and soft fruits though death to large fruit trees. And a river can keep the area too cool in summer with too much humidity, to say little of floods…

After the lie of the land the next crucial factor has to be water. You just cannot garden productively if there is both a shortage of rain and no other supply. A river or stream nearby may seem attractive but better to choose a garden in an area suited by rainfall to your proposed crops. The South East of England is too dry most years to grow spinaches, swedes, Chinese cabbages and so on unless you irrigate or your soil is unnaturally moist. Equally; heavy rainfall in the West make fruits such as cherries and strawberries mould away but is favourable for most vegetables. (And the relative warmth in the West also makes it less suitable for many fruits especially such as pears, peaches, apricots and so on as these need a long cold spell to go dormant and wake up from. In equable climates they grow on too long lose vigour and fade away. To say little of the lack of summer sunshine to ripen the fruits.) Water is so important that all rainfall on roofs, paths and drives etc. ought to be easily stored, not only for preference but as the hose is likely to be unavailable when you need it most. Wells are a great asset though their water is cold, if old and dried out they could be converted to storage cisterns. Likewise ponds and springs are immensely valuable though the latter may indicate waterlogged areas and can cause cold soil conditions. Not only must you have a reliable source of water but you must be able to get it to the crops and thus any garden where it is difficult to move about will be irksome when watering. Crowded or narrow footways, slippery surfaces and uneven ground can be most disconcerting.

The next most important factor is probably your soil. Although you can improve poor soils amazingly it’s obviously easier if you can have a deep rich loam to start with. The sort of thing you have when you dig up an old water meadow. (Though how you are going to find the soil from an old water meadow on a south slope up near the brow of a hill I’m not sure…) Generally it’s best to avoid thin acid sandy and silty soils as though they can be got to grow excellent root crops and they are a joy to dig they require inordinate amounts of well rotted manure or compost to keep them in good heart. However a wet heavy clay is far worse. It may be inherently richer in plant nutrients, it may hold more moisture longer, but it’s a colder soil, late to crop and very very tiring to work. Especially avoid soils that have bluey grey clay near the surface as the colour tends to indicate anaerobic conditions and waterlogging. A clay that looks reddish may have a build up of iron especially if it’s in a thin band (which may indicate ‘panning’ and need breaking up). But reddish clay subsoils show air is getting to them and they should be good to crop. That rich deep loam will suit most fruit and vegetables and is effectively much the same as rotted down grass turves grown on good soil. Both are composed of plentiful humus and fibre to hold moisture, plenty of sand to give a grittiness and aeration and enough clay to make it fertile and moist but without making it too heavy and prone to cracking. That gorgeous dark moist crumb texture of the richest loams is simply years of accumulated worm droppings which are water stable creating good granulation as well as full of fertility.

The relative acidity or limeyness or ph of your soil will make some crops thrive or fail. Neutral to slightly limey soil suits most vegetables and top fruits with most soft fruits happy in neutral to very slightly acid. But if you want a blueberry plantation you must choose a wet acid soil not just a wet one. The stone fruits, cabbages and legumes enjoy lime and loathe acid conditions so if these are your forte choose a deep rich limey loam. However beware a thin soil over chalk which is incredibly hard to crop well.

We all want a walled garden, but it need be a big one. A small one should be called a cell and will be as confining. Walls may be sunny but they also cast heavy shade and cause colder soils. (Many sorts of hedge allow some air and some light to pass through and may be a better choice for orchards and fruit cages in windy areas). Walls also create gusts and eddies of wind causing more damage however putting trellis atop will reduce the problem. Then there is air circulation. Thick hedges and high walls can cause stagnant spots and these will not be good for most crops and are particularly bad for gooseberries which need good air flow. On the plus side good walls or appropriate hedges will keep off much wind which will significantly improve the soil temperature and increase crops (the majority do not thrive in wind speeds of more than six miles per hour). A wall gives shelter to several times it’s height so it pays to think big and even to have internal walls or hedges as well. Indeed if you have the cash then have your walls made or lined with red brick, even if stone is free, as brick holds more heat and can be hosed down to create warm moist air which discourages many pests such as red spider mites. (Most types of stone stay colder and water hosed on runs off.)

Beware gardens nestling amongst dense trees however pretty; these will rob the soil as well as shade you out all winter and drive you mad with drips. And the wildlife will be prolific and thieving. You are unlikely to overlook accommodation for yourself but it’s absolutely necessary to be on site and not elsewhere, and if the garden is large then your home should be near centrally placed. But also make sure there is space for a greenhouse or plastic tunnel in full sun as cover is such an important aid. And so is electricity; ensure there is an adequate supply safely available.

And finally; if you do manage to find that ideal spot can you afford to buy me another next door?