How Much Sun Does Your Balcony Actually Get?
Most container garden failures trace back to one misjudged number: how many hours of direct sun a spot really receives. Seed packets say "full sun" and balconies rarely deliver it. Here is how to measure what you have and match plants to it honestly.
The three-reading method
Do this once, on a clear day, and write the results down. You need nothing but a phone clock.
- 9:00 — stand where the pots will go. Note which areas are in direct sun.
- 13:00 — repeat. Note what changed.
- 16:00 — repeat. Note what changed.
Add up the hours each specific spot was in direct sun. Ignore bright-but-shaded areas: indirect light looks cheerful to your eyes and is worth very little to a fruiting plant. A spot that is only sunlit between 13:00 and 16:00 is a three-hour spot, even if it feels hot.
What each level actually supports
| Direct sun | Reliable crops | Realistic expectation |
|---|---|---|
| 6–8 hours | Tomato, pepper, aubergine, cucumber, courgette, basil | Full harvests, fruiting crops ripen properly |
| 4–6 hours | Beans, chard, kale, carrots, beetroot, dill, coriander | Good leaf and root production, fruiting crops give a reduced crop |
| 2–4 hours | Lettuce, spinach, rocket, parsley, chives, mint | Leaves grow larger and more tender than in full sun; no fruiting crops |
| Under 2 hours | Herbs grown for leaves, microgreens | Slow, leggy growth; treat as a windowsill herb garden |
Factors that quietly change your number
- Reflected light. A pale wall, white railing or light-coloured floor bounce can add roughly the equivalent of an hour. A dark brick wall opposite does the reverse.
- Overhead cover. A balcony directly beneath another gets zero rain and often surprisingly little sky light. These spaces run hotter and drier than their sun hours suggest.
- Glass. Behind a window, light intensity drops by roughly 20–40% depending on glass type and cleanliness. A windowsill that looks blazing gives your plants the equivalent of part shade.
- Season. The sun is higher in June and lower in October. A spot with seven hours in June may have three in September. Re-measure if you are planning an autumn crop.
Photograph your balcony at each of the three times and keep the photos. The shadow line is much easier to read in a photo than from memory, and it makes planning next season trivial.
If you have a shaded balcony
Shade is not a dead end, it just changes the crop list. Leafy greens genuinely do better in part shade — they bolt (run to seed) more slowly and stay tender. Work with it:
- Grow lettuce, rocket, spinach, chard, kale, parsley, coriander, chives and mint.
- Skip tomatoes, peppers, cucumber and courgette entirely rather than fighting for a handful of fruit.
- Choose compact or dwarf varieties; they need less energy to reach harvest size.
- Water less often. Shaded containers lose far less water, and overwatering is the second most common shade-garden mistake after wrong crop choice.
- Use pale containers and light-coloured saucers to bounce whatever light there is back onto foliage.
If you have too much sun
A south-facing balcony in a heatwave can exceed what plants tolerate, particularly in containers, where roots hit 40 °C in black plastic. Mitigations, in order of effectiveness: move pots into the shade of larger pots during the hottest hours, group containers together so they shade each other's sides, use pale or fabric containers, and add a 3–5 cm mulch layer of straw or bark on the surface to slow evaporation.
Common questions
Does afternoon sun count as much as morning sun?
Afternoon sun is stronger but shorter-lived. What matters is total hours of direct light, so three hours at midday and three hours in the afternoon are equivalent for plant purposes.
Can I grow tomatoes with only four hours of sun?
You can grow the plant, but you should expect a small, late crop. Cherry and currant types cope better than large-fruited varieties. With four hours, leafy and root crops are the better bet.
Do reflective surfaces genuinely help?
A pale wall can meaningfully increase the light a plant receives, and a dark wall absorbs it. It will not turn a shady balcony into a sunny one, but it shifts crops near the boundary.
I have a north-facing balcony. Is anything worth growing?
Yes: mint, chives, parsley, lettuce, rocket and spinach all produce in low light, and leaves stay tender for longer because they bolt more slowly. Skip anything fruiting.
Should I re-measure my sunlight later in the year?
Yes. The sun sits much lower in autumn, so a spot with seven hours in June may have two or three by October. Re-measure in early September if you are planning autumn and winter crops, and move containers accordingly.