May 9, 2016

No Backyard, No Problem. Start Your Balcony Garden.

The confines of city living bedevil anyone who longs to call a patch of plants their own. In my own New York City life, I have gardened everywhere from a sunny bathroom, to window ledges, to terraces and a rooftop, and now to a backyard in Brooklyn. But the narrow herb box on my window ledge on Flatbush Avenue gave me no less pleasure than a larger space does. I was able to reach through that kitchen window to pick my own thyme, sage, and lettuce for supper. This small act of self-sufficiency tamed the city, and calmed me. 

Eager to start a window box or balcony garden of your own? Here is a seven-step primer to adding some green to your own corner of the concrete jungle.

1. Exposure

From a lush balcony to a flowerpot-lined entryway, your garden success starts with sunshine exposure.From a lush balcony to a flowerpot-lined entryway, your garden success starts with sunshine exposure.

Exposure is about direction, and determines how much sun your space receives. Different plants require different light: full sun (6-plus hours of direct sun), semi-shade (3–6 hours of direct or intermittent sun), or full shade (no direct sun).

But most cityscapes have micro-exposures, determined by surrounding buildings. Even a south-facing terrace can be in full shade, thanks to the 40-floor apartment building across the street.

Plotting the course of the sun across your outdoor space is essential to choosing the right plant for the right place.

2. Climate

Let it snow, won’t let it grow. Find winter-hardy plants that will survive through all seasons.Let it snow, won’t let it grow. Find winter-hardy plants that will survive through all seasons.

Not sure which seeds to get or when to plant them? Determining your USDA Plant Hardiness Zone is essential to helping you choose plants that will thrive in your region. This is how you will know when the first and last average dates are in your region, which will help you time your seed-sowing, as well as guide your plant choices. It also determines which plants are hardy enough to survive winter and return the following spring.

If you are planting from seed, the seed packet will tell you when to sow indoors or outdoors, based on the average frost dates in your zone. For example, cool weather greens like arugula, spinach, and cilantro like being planted in cold weather, but tomatoes, beans, and basil hate being chilly and must wait until the minimum temperatures are above 50’F (which is why many people start them indoors, to transplant as soon as temperatures warm up). For additional support, sign up for a seeds of the month club, like Grow Journey, which provides advice specifically for seeds they send you every month. And zip to your local nursery to choose perennials and shrubs adapted to conditions in your region.

3. Plants

For good plant advice, your local nursery is the best resource.

Annuals pack punch: flowers, herbs, and crops are a seasonal fix for tight spaces, like skinny windowboxes and pots, for one season’s dramatic effect.

Perennials (plants returning after winter dormancy) grow well in larger windowboxes and pots. Flowering perennials bloom for a period of 2–6 weeks, so choose a collection whose bloom is staggered over the growing year. Repeat some of the plants in different spots and use different heights and textures.

Perennials can be edible: If you have 6-plus hours of sun, ever-bearing strawberries are very rewarding, with new fruit every 3-4 weeks. If your garden is shadier, choose Alpine strawberries.

Shrubs grow well in pots 16 inches or more in diameter. Yes, you can grow your own fruit! Blueberries and black raspberries grow well with as little as four hours of direct sun.

Climbers use tight spaces creatively and make the most of what you have.

Trees prefer a larger container (square is the most stable). Figs love full sun, and serviceberries are an indigenous option if you love unusual fruit. Every few years, containerized trees benefit from a root-pruning to prevent girdling.

4. Containers

Your choice of containers can’t be contained to any one size, diameter, or material.Your choice of containers can’t be contained to any one size, diameter, or material.

As long as it can hold potting mix and has drainage holes, almost anything is a suitable container for a plant. Coffee cans, vintage coal scuttles, growbags, galvanized metal or plastic buckets, plastic, fiberglass, and wood planters are all lightweight options. Terra cotta and hypertufa are heavier choices if weight is not a prime concern.

5. Water

Three rules: Small pots dry out faster than large. Do not rely on rain. Soak, don’t sprinkle.

Most new gardeners overwater, because they worry. But overwatering is worse than underwatering. Feel the soil. Stick your finger in about an inch. If the potting medium feels damp and looks dark, you don’t need to water. If it feels dusty and looks pale, soak the container until water seeps from the drainage holes. (If using self-watering containers, the built-in wells must be dry before you top the water up again.)

To cut down on watering duties, add a hydrogel to the potting mixture when filling the planter. This absorbs and holds water in reserve. Follow the package instructions precisely unless you want a jelly-splosion the first time you water.

6. Potting Soil

Get dirty and eat clean with rich soil for organic produce.Get dirty and eat clean with rich soil for organic produce.

Despite its name, potting soil contains very little, if any, actual soil. (Topsoil is heavy and drains too poorly for a planter.) Instead, potting mediums are a mixture of products such as compost, coir, bark, worm castings, and perlite. Read the bag for a list of ingredients. If you are growing organically and sustainably, avoid bagged mixes that contain peatmoss and synthetic fertilizers.

7. Planting

May your outdoor garden—and green thumb—bloom for sweet success!May your outdoor garden—and green thumb—bloom for sweet success!

To minimize leakage of potting soil, lay a piece of bugscreen or landscape fabric over the drainage hole (but water must still exit freely). Fill the pot with potting mixture and make a well for your plant. Tip your plant out of its nursery pot (or its first pot if you grew it from seed) and loosen the roots. Place gently in the well, add potting mix, and tamp down so that the mix is flush with the flat top of the plants’ retained soil. Water immediately.

Happy planting! Post your tips in the comments below and share photos of your green-thumb progress with @Zipcar on Instagram.

Marie Viljoen gardens in Brooklyn and writes about food, flowers, and plants you can eat. Her gardens have been featured in the New York Times, Martha Stewart Living, and many other publications. Her blog is 66 Square Feet.