Which way should a vegetable garden face, and how many hours of sun does it really need

Poor soil can be fixed: time, compost, sometimes several seasons, but it is doable. A shortage of water can be fixed too. Light cannot. You cannot move the sun, your neighbour's wall, or the tree that has been growing along the boundary for thirty years. That is why aspect deserves to be settled before anything else, before you even decide what to sow.

Measure it, don't estimate it

Most gardeners are wrong about how much sun their plot gets, and always in the same direction: they overestimate. A glance out of the kitchen window at midday in June gives the impression of a garden flooded with light. That is one snapshot, nothing more.

The method worth using costs almost nothing. Pick a clear day and look at your plot three times: mid-morning, around midday, and mid-afternoon. For each part of the ground, note whether it is in direct sun, in solid shade, or in that in-between state where light filters through foliage. Three readings are enough to sketch an honest map.

The second step matters even more: do it again in a different season. The sun's height above the horizon changes enormously through the year, and the shadow cast by a tree or a building lengthens the lower the sun sits. A plot surveyed in March, when the sun is still low and deciduous trees are bare, is not the same plot in July, when the sun rides high but the neighbouring hedge has doubled in density. Those two effects pull in opposite directions: one opens the light up, the other closes it down. Only two seasons of observation will tell you which one wins in your garden.

Full sun, partial shade, shade: what the words cover

The categories printed on seed packets are horticultural conventions. They are useful because they are shared, not because they rest on any field measurement.

By convention, full sun means roughly six or more hours of direct sun a day during the growing season, partial shade somewhere between about three and six hours, and shade less than that. Different sources give slightly different cut-offs, which tells you what these numbers are: convenient landmarks, not constants.

What each category genuinely allows is worth stating plainly. Full sun opens up the whole vegetable garden. Partial shade narrows the choice but stays thoroughly workable, and in a hot climate it is an advantage, since a few hours of afternoon shade spare plants the worst of the day. Real shade closes the door on a productive plot: it will happily hold a compost bin or a few tolerant ornamentals, but expecting a crop of fruiting vegetables there is an expensive illusion.

Rank your crops by how much light they demand

There is a reasonably robust hierarchy, and it follows a simple logic: the more energy the part you harvest costs to build, the more light the plant needs.

Fruiting vegetables are the hungriest. Tomatoes, peppers, aubergines, melons, cucumbers, squash, pole beans: each has to flower, then set fruit, then ripen it. That programme is expensive, and it is paid for in sunlight. Putting them in partial shade will not kill them, but it delays and shrinks the harvest.

Roots and bulbs sit in the middle. Carrots, beetroot, turnips, onions, garlic and potatoes need light to fill their storage organ, but they cope with a less generous position.

Leafy vegetables are the most tolerant, which makes sense: the leaf is both the organ you harvest and the organ doing the work, with no costly transfer into a fruit. Lettuce, spinach, chard, rocket, corn salad, leafy brassicas and most soft herbs other than the Mediterranean ones are the natural backbone of a moderately lit plot. Several of them actually benefit from summer shade, which delays bolting.

Row orientation is a rule of thumb, not a law

The advice to run rows north to south turns up everywhere, and it has its logic. In the northern hemisphere, a row laid out that way sees the sun travel along its length from east to west, which spreads light across both flanks and reduces the risk of one tall row shading its neighbour all day.

That is a starting point and nothing more. On sloping ground, erosion and runoff take priority: you run the rows across the slope, whatever the compass says. Where light arrives from a single side because of a wall or a hedge, the geometry of that opening dictates the layout, not north. And in a small garden where rows are three metres long, mutual shading matters far less than access and comfortable harvesting.

The rule that survives every special case fits in one sentence: place tall crops where they will not shade short ones. In the northern hemisphere that means putting them at the north end of the bed, and it is a south-facing wall that acts as the warm wall. In the southern hemisphere — Australia, New Zealand, southern Africa, most of South America — everything flips: the north-facing side receives the most sun, a north-facing wall is the warm one, and tall crops belong at the south end of the bed. Gardening advice published without stating its hemisphere is, quite literally, back to front for half its readers.

Walls, hedges and buildings: shade and its opposite

A vertical obstacle plays two opposite roles depending on which side of it you stand, and it is easy to notice only one.

On the shaded side, it subtracts hours of sun, and it subtracts more of them the taller it is and the lower the sun sits. This is where the two-season survey earns its keep: a building that blocks nothing in July can write off an entire strip of ground in March and September, precisely when you are starting crops off and stretching the season at the other end.

On the lit side, the same obstacle becomes an asset. A wall that catches sun for much of the day — south-facing in the northern hemisphere, north-facing in the southern — stores heat and releases it slowly into the evening. Its foot is the most favourable microclimate in the garden: put the tender crops there, the earliest sowings, the Mediterranean herbs, rather than salad rows that would do just as well anywhere else. A hedge behaves differently: it lets diffuse light through, but its roots compete for water well beyond the spread of its canopy.

Working with a plot that does not get much sun

If your survey lands on three or four hours of direct sun, the honest answer is not to hunt for a miracle variety. It is to reorganise the plan.

Three levers genuinely exist. The first is pruning: one low branch removed, one hedge brought back to a sensible height can hand you back an hour or two of light, and that is often the only substantial gain available. The second is relocating: the best square metres of a garden are not always the ones you had earmarked, and a vegetable strip along a well-lit path beats a beautifully drawn bed in a dark corner. The third is crop choice: commit to a leaf-and-herb plot instead of repeating the same disappointing tomatoes every year.

You also have to accept what will not work. A three-hour garden will not ripen melons, and no technique closes that gap. Saying so plainly saves whole seasons.

What Marmanda does with aspect

In Marmanda, the orientation and exposure you record are part of your garden's description, alongside soil type. That information feeds into where crops are suggested: a bed you have marked as partial shade will not draw the same proposals as one in full sun. Every fact the app shows states where it came from and how far it holds, including when the honest answer is that a figure is a horticultural convention rather than a measurement. Marmanda does not calculate the shadows cast across your ground and does not model the sun's path over your garden: the three-times-a-day, two-seasons survey remains your work, and it is what gives everything else its value.