Starting a Balcony Garden

Check the space before buying pots

The first step in starting a balcony garden isn't choosing what to plant but understanding what kind of space your balcony is. Even within the same apartment complex, light and temperature vary completely with the floor, orientation, buildings across the way and type of windows. A plant can't change those conditions, so the right order is to pick crops that suit them. Spend a day or two checking in the morning, at midday and in the afternoon whether direct sun reaches the floor and shelf height of your balcony, and write down the times. Keep in mind that the sun sits at a different height in summer and winter, so the sunny spots shift with the seasons.

What to expect from each orientation

A south-facing balcony gets sun for most of the day, so you can try even fruiting vegetables. An east-facing one gets morning sun and afternoon shade, which suits leafy greens and herbs well. West-facing balconies get strong afternoon sun and become very hot in summer, so watch that leaves don't scorch at midday. North-facing balconies get almost no direct sun and make growing food hard. Rather than forcing fruiting crops, it's more realistic to grow microgreens and other quick crops, or to consider supplemental grow lights.

• South: cherry tomatoes and peppers are possible
• East: mostly lettuce, scallions and herbs
• West: watch for summer afternoon heat and leaf scorch
• North: consider microgreens or grow lights

Window glass cuts the light

A balcony with closed windows gets weaker light than the outdoors. Each pane of glass the light passes through absorbs some of it, and double glazing absorbs more. Insect screens and window frame shadows block light too. So even a home that looks sunny from outside may deliver less light to pots indoors than you'd expect. Opening the windows on fine days lets in both light and air and makes plants sturdier. Place pots as close to the window as possible and at a height where light reaches them well, such as on a shelf rather than the floor. If a plant leans to one side, turn the pot every few days.

Wind and temperature

Plants need some air movement to grow strong stems and to let moisture escape from between leaves, which reduces disease. A balcony that stays shut traps stale air, inviting fungal disease and insects, so ventilate at least once a day. On the other hand, open balconies on high floors can be so windy that pots tip over and soil dries out fast. Temperature matters too. A closed balcony at midday in summer can get far hotter than outside, and on winter nights it can drop close to freezing. Put a thermometer out and log the highs and lows for a few days; it makes it much easier to decide what you can grow and when.

Weight, drainage and safety

Pots full of soil get heavy once they're wet. Rather than lining several large pots against one wall, spread them out, and make sure any shelving can take the weight. Hanging pots outside the railing or setting them on a window ledge risks them falling, so avoid it. Always use saucers when watering, and don't let overflow water and soil clog the drain. If the balcony floor isn't waterproofed, or the balcony has been converted into indoor space, water can leak into the unit below, so it's safer to water in one designated spot.

Your first shopping list

At first, buying only the essentials is enough. Choose pots with drainage holes in the bottom and buy matching saucers. For soil, a bagged potting mix brings fewer disease and pest worries than soil dug from a yard. Starting from seedlings shortens the time to harvest and reduces failures. When picking seedlings, look for deep green leaves, thick, short stems and no insects on the leaf undersides. If masses of roots are poking out of the bottom of the nursery pot, the seedling may have been sitting around too long.

• Pots with drainage holes, plus saucers
• Bagged potting mix
• One or two healthy seedlings
• A watering can and a small trowel
• Plant labels and a notebook

Common mistakes and the value of notes

The usual balcony garden mistakes are planting fruiting crops in a spot without enough light, watering every day out of habit, and planting too much at once. Avoiding just these three greatly improves your odds of a first harvest. Jot down the planting date and variety, watering days, the first flower and each harvest, and you won't repeat the same mistakes next year. Using a date calculator to count days since planting also makes it easier to gauge growth stages. Your own notes end up being a more accurate guide to your balcony than anyone else's advice.