There are several important points to be considered when gardening on an apartment balcony:
Weight Is Critical
The weight of the pots, soil, water in the pots and plants, can be considerable when added together.
For this reason, do not use real soil or potting soil on apartment balconies.
And consider using the new fabric flower pots as they’re very lightweight
Only use soilless peat-based soils such as ProMix or Fafard mixes. Remember that you have to carry everything up to whatever level you’re on, so the lighter the better.
Also be aware that there may be legal considerations depending on your lease and the building to gardening on an apartment balcony.
Pollination of Vegetables
If you are trying to grow vegetables on higher balconies, you may find that bees, moths, beetles etc are not regular visitors to your balcony.
You will have to do the pollinating yourself if, for example, you are trying to grow tomatoes. The easiest way to do this is to take a few minutes, think like a bee, and wander around the balcony humming in a buzzing sound and gently shaking each blossom set. Mind you, you could always gently shake each blossom set sometime in the early afternoon when the pollen is fresh or as soon as you get home from work and forget making bee-like sounds. It just adds a certain “something” to the balcony garden if you pretend to be a bee. 🙂
(hint: do not do this while the neighbours are on the balcony or your significant other is present.)
Some vegetables will wind-pollinate (tomatoes may do this if the blossoms move about enough) but most will depend on your assistance with a finger or small, flexible paintbrush. (I use my finger on lilies etc.)
Watering is a pain if you have to carry all the water. You can purchase flexible (curl-back-up again) apartment-sized hoses to run the water directly to the plants. The rules for watering any container are the same no matter whether they are on a balcony sitting on the ground or twenty stories over Manhattan.
Water until the water runs out the bottom of the pot.
Overwintering annuals have to be brought indoors. If you’re overwintering your tropical plants, then simply move them to the other side of the windows for the winter.
Overwintering perennial plants can be a bit dodgy. I have found that some roses and perennials(the hardier sorts like Explorer and Daylilies) will overwinter in a container if they are leaned against a warm wall and then insulated with old blankets on their cold balcony side and underneath.
In other words, protect them from the cold on the cold side but leave them open to the “leaking” warmth on the warm side of the balcony. This, of course, depends on both the severity of the winter and where you’re trying to garden. You won’t overwinter perennials outdoors on Alberta balconies but you might get away with it in Philadelphia.
In general, when gardening on an apartment balcony, treat all plants as annuals.