In this guide
The balcony looks bright from the living room. There is sun on the railing, and the afternoon feels warm enough for tomatoes. But the pot beside the door might spend that same afternoon beneath the upstairs balcony’s shadow.
To work out your balcony’s light, check the spot where the leaves will sit at different times of day. Note when direct sun reaches it and when it leaves, along with anything that blocks it. Compare that pattern with the needs of the plant you want to grow. A few notes and photographs are enough to begin describing the spot, though they will not give you a precise rating for the whole balcony.
Check where the plants will sit
Start with one or two usable positions. Even in a sunny strip, a pot needs to leave the door clear and its saucer within reach. Allow room for walking and sitting, as well as ordinary plant care.
Give each position a simple name, such as “beside the door” or “outer corner.” If you already have plants, watch the light on their leaves. If you are planning a container, consider the height at which its foliage will grow. A floor-level shadow does not necessarily describe the light reaching a taller plant, and a sunny railing does not establish that the pot below it gets sun.
A covered balcony can have several different growing conditions within a few feet. Look for the obstruction that matters at each position: the slab above, a solid railing, a side wall or a neighboring building. A compass direction helps orient the space, but it cannot tell you which of those obstacles blocks the light.
Tell direct sun from bright shade
Direct sun reaches the foliage without a roof, wall or other opaque obstruction in its path. On a clear day, a sunlit leaf or object often casts a distinct shadow, a useful clue that direct rays are reaching the spot.
Bright shade can still look inviting. An open balcony may receive daylight from the sky even while its roof keeps direct sun off the plants. The Royal Horticultural Society’s shade guidance distinguishes direct sunshine from diffuse light and describes open-to-the-sky positions screened from direct sun as light shade.
Light passing through tree leaves or an open screen may produce moving patches of sun. Note that as filtered or dappled exposure rather than assuming the whole period is uninterrupted direct sun. Reflected light from nearby surfaces can also brighten a position; record it separately from the periods when direct sun reaches the leaves.
Plants still receive useful light in shade. These descriptions help you record what is available, but a shadow alone cannot tell you the total amount of light a plant receives over a day. If clouds soften the shadows or you cannot confidently identify the exposure, note the uncertainty and check again.
Record when direct sun reaches each spot
Pick a day when the weather lets you see the building’s sun and shade pattern. Keep the date with your notes. Check the same positions across the daylight hours, including evening if sun can reach the balcony then. Include any period when you already suspect sun comes around a corner.
The UC Master Gardener Program of Alameda County recommends observing a proposed growing location at several points through the day and accounting for obstructions and time of year. You do not need to watch every minute to begin understanding the pattern.
Record whether direct sun is on the intended foliage position, not just somewhere on the balcony. When you notice it arriving or leaving, write down the approximate time. If a wall interrupts the exposure and sun returns later, keep those periods separate. A photograph from the same viewpoint can help you compare the shadow edges.
The table below is hypothetical; it does not describe a measured balcony or predict yours. It assumes you have watched the transitions often enough to estimate when sun arrives and leaves:
| Growing position | Direct sun observed | What the note tells you |
|---|---|---|
| Outer corner at foliage height | About 9 to 11 a.m., then about 1 to 2 p.m. | Roughly three hours in two periods, with shade between them |
| Beside the door at foliage height | No direct sun seen during the day’s checks | Describe the remaining brightness and check whether you missed a short sun period |
Two sunny observations do not establish that a spot stayed sunny between them. If you saw sun at 9 a.m. and again at noon, a nearby building could have interrupted it. Check the uncertain period before recording three continuous hours.
If you can only look before and after work, those observations are still useful. Mark the middle of the day as unknown rather than filling it in. Repeat on a day when you can check it. Illinois Extension’s garden sun-chart activity also recommends watching the chosen spot over several days.
Compare the result with the plant label
Compare each pot’s exposure with the light requirements of the plant you want to put there. A single label for the whole balcony can miss those differences.
For reference, RHS’s UK guidance defines full sun as more than six hours of direct sun per day at midsummer and partial shade as three to six. Its light-shade category also includes bright positions without direct rays. Use those definitions alongside the particular plant’s requirements and your local conditions. Keep the season in your notes when making the comparison.
For an edible example, University of Maryland Extension recommends six to eight hours of direct sun for warm-season container crops such as tomatoes and peppers, and three to five for cool-season crops such as lettuce and spinach. A spot with roughly three observed hours therefore suggests different crop possibilities from one with a long sunny period. It does not guarantee a harvest, or make every cooler-season crop suitable during hot weather.
Also note when the sun arrives. A short period of hot afternoon exposure can create a different care problem from morning exposure. If the proposed plant needs protection from afternoon sun, a total of “three hours” is an incomplete description.
When a plant’s guidance and your observations do not fit, check another usable position or choose a plant suited to the spot. Raising or moving a pot is only worth considering if the new foliage position receives appropriate light and you can still tend it comfortably. Our guide to watering balcony plants without an outdoor tap can help you judge the care routine alongside the placement.
Recheck when the season changes
Your notes describe the balcony at the time you made them. The same position may receive different direct sun later, even if none of the pots has moved.
In much of the United States, the sun travels higher across the sky in summer and lower in winter. The US Department of Energy’s passive-solar guidance explains how an overhang can block higher summer rays while allowing lower winter rays beneath it. That geometry can matter on a covered balcony too: longer summer days do not automatically mean more direct sun reaches a plant tucked under the slab above.
The result depends on location, orientation, the overhang and the plant’s position. Your balcony might show a different pattern. Nearby trees can add shade when they leaf out, while neighboring structures cast changing shadows. Repeat observations at the positions that matter when those conditions change, especially before planning a different season’s planting.
Keep the notes with a photograph or use our small-space garden planner to record the broad light pattern and arrange the pots. The planner helps with placement; it does not calculate sun hours or predict future shade.
Before buying the next plant, choose its position and check its light needs against your notes. If the deciding period is still unknown, observe that period first. You only need to understand that workable spot to make this choice.