Garden 
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Measure it, do not estimate it: on one clear day, check the balcony every hour from sunrise to sunset and write down whether direct sun is actually landing on the floor. Add up the full-sun hours. That number sets everything else. Four hours means leafy crops, six means most fruiting crops, eight means anything. Compass orientation tells you what to expect before you measure; the hourly log tells you what is true.
Nearly every disappointing balcony garden traces back to this number being wrong. A pepper in four hours of sun grows into a healthy-looking plant that flowers and then quietly drops every flower, and the owner usually blames the fertilizer. It was the light.
The Hourly Shade-Tracking Method
This takes one day and no equipment.
- Pick a clear day close to the season you plan to grow in. Late spring is ideal for a summer vegetable garden. A cloudy day tells you nothing.
- Make a simple grid — hours down one side, and if the balcony is more than a few feet deep, split it into three zones across the top: rail, middle, wall.
- Check on the hour, from sunrise to sunset. For each zone, mark S for direct sun, D for dappled or partial, and X for shade. Take a photo from the same standing spot each time; it takes ten seconds and gives you something to compare against in August.
- Total the S marks per zone. That is your sun-hour count, and it will very likely differ by two or three hours between the rail and the wall.
- Count D as half an hour at most. Bright shade is not sun. Reflected light off a pale wall is a real bonus for leafy crops and close to worthless for tomatoes.
If you cannot be home all day, a phone on a windowsill taking a photo every hour on a timer does the job, and so does asking whoever is home to glance out four or five times. The point is the record, not the ceremony.
Repeat it once mid-season. The sun's path shifts enough between May and July to change the answer, and deciduous trees leaf out. A garden planned in April on a balcony shaded by a maple in June is a common and entirely avoidable disappointment.
What Compass Orientation Predicts
Stand at the rail and look outward — that direction is your balcony's aspect. A phone compass takes five seconds. In the continental US, this is what each aspect typically delivers in summer:
| Aspect | Typical direct sun | When it arrives | Character |
|---|---|---|---|
| South | 6–10 hrs | Mid-morning to mid-afternoon | The best growing aspect. Hot, bright, long season. |
| Southwest | 6–8 hrs | Late morning onward | Excellent, but heat-stressed in July and August. |
| West | 4–6 hrs | Afternoon and evening | Intense, dry, hard on pots. Great for peppers and Mediterranean herbs. |
| Southeast | 5–7 hrs | Early to mid-afternoon | Gentle and productive — arguably the easiest aspect to garden. |
| East | 4–6 hrs | Sunrise to midday | Cool morning light. Ideal for salad, chard and herbs. |
| North | 0–2 hrs | Early morning / late evening edges only | A shade garden. Foliage, mint, some lettuce. |
Two adjustments to that table. Buildings and trees override aspect completely — a south-facing balcony with a ten-story block 40 feet away can get less sun than a clear east-facing one, which is exactly why you measure rather than assume. And west is hotter than the hour count suggests: afternoon sun arrives when air temperature and masonry heat are already at their daily peak, so a west balcony punishes containers far more than a south one delivering more total hours.
The Overhang Effect Nobody Expects
If there is a balcony above yours — and in most apartment buildings there is — the sun does not simply arrive and leave. It reaches a certain distance in from the rail, and that distance changes through the year in the opposite direction to what people assume.
The mechanics are simple. The sunlit strip along your rail is roughly the height of the overhang above your floor, divided by the tangent of the sun's altitude angle. A typical 9-foot ceiling height gives:
| Season (at 40° N) | Noon sun altitude | Sunlit strip from the rail |
|---|---|---|
| Summer solstice (late June) | ~73° | ~2 ft 9 in. |
| Equinox (late March / late September) | ~50° | ~7 ft 6 in. |
| Winter solstice (late December) | ~27° | ~18 ft — full depth |
So a covered balcony receives its deepest midday sun penetration in spring and fall, and its shallowest at midsummer noon, when only a narrow band at the rail is lit. This is why plants that thrived in May sometimes stall in July on a covered balcony, and why the fix is physical rather than horticultural: move containers out toward the rail for the six weeks either side of the solstice, and back in as the sun drops.
Noon altitude varies with latitude, so adjust: around 30° N (Phoenix, Houston, Jacksonville) the summer noon sun sits near 83°, which pushes the lit strip down to about 15 inches. Around 47° N (Seattle, Minneapolis, Bangor) it peaks near 66°, giving roughly 4 feet. The further north you are, the more forgiving your overhang.
What 4, 6 and 8 Hours Actually Permit
The mnemonic worth keeping is leaves 4, roots 6, fruits 8. Here is the honest version:
| Sun hours | What grows well | What will disappoint you |
|---|---|---|
| 8+ | Everything: tomatoes, peppers, eggplant, squash, melons, beans, all herbs | Nothing — but watering becomes the limiting factor |
| 6–8 | Tomatoes, peppers, bush cucumbers, beans, strawberries, basil, rosemary | Melons and full-size squash; big tomatoes ripen late |
| 4–6 | Chard, kale, lettuce, spinach, bok choy, scallions, radishes, beets, bush peas, parsley, cilantro, mint | Any fruiting crop — flowers set poorly or drop |
| 2–4 | Leaf lettuce, spinach, arugula, mint, chives, parsley; ferns, hostas, begonias, impatiens | Root crops stay small; herbs get leggy and weak-flavored |
| Under 2 | Foliage plants and shade ornamentals | All edibles. Grow for looks, not for the kitchen. |
Two things are worth knowing about the boundaries. Fruiting crops do not fail gracefully — a tomato at five hours does not give you 60 percent of a harvest, it gives you a large green plant and a handful of late fruit, because the plant spends what light it gets on leaves first. Penn State Extension puts the floor at six hours of direct sun a day for tomatoes and peppers to fruit well. And leafy crops in the 3-to-5-hour band are often better than in full sun, since lettuce, spinach and cilantro bolt in heat and appreciate an afternoon of shade — the same Penn State guidance notes that lettuces and kale specifically prefer some shade rather than full sun.
Squeezing More Light Out of What You Have
You cannot move the building, but four things reliably add usable light.
Reflect it. A white or pale wall behind containers bounces a surprising amount back onto the plants. A sheet of white board, a light-colored outdoor rug or simply painting a permitted screen white all help, and this is the cheapest improvement available on a dim balcony.
Put the tall things where they belong. On a north- or east-facing space, tall plants at the rail block what little direct sun arrives. Reverse the usual layering and keep the tallest at the sides rather than the front.
Go vertical toward the light. Wall-mounted pockets and stacking towers move plants up into the band of the balcony that clears the railing solid panel — often the difference between two hours and four for the lower plants. The formats are compared in vertical planter vs grow bag vs raised bed, and our ranked vertical garden planters covers which designs handle the watering demands that come with height.
Use the rail itself. A solid balcony railing casts a permanent shadow across the first foot or two of floor, so the top of the rail is often the brightest real estate you own. Over-the-rail boxes put salad and herbs directly into it; fit and drainage are what separate the good ones, which is what our railing planter rankings weigh.
Move the pots. The most underrated tool on a balcony is a set of rolling plant caddies. Three dollars of casters turns a static container into one that follows the sun, and on a space with one bright corner it can double the effective light a tomato receives.
Where to Go Next
Once you have the number, everything else follows: pick crops that match it in vegetables that grow well in containers, size the pots properly using container sizes by crop, and deal with weight, wind and drainage in the balcony garden starter guide. More sun means more watering, so watering containers in summer heat is the natural follow-up. Everything sits under our small-space gardening hub, and our product rankings come from aggregated owner reviews rather than first-hand handling — the method is on how we rank.