Build a Farm to Fit

Photo via iStockphoto.

If You’re Working With …

A Rooftop
While guidelines for rooftop gardens have yet to be formalized in Boston, follow the code for building a roof deck and you’ll be in good shape. Then hire a pro: Somerville-based Recover Green Roofs can turn your black-tar topper into an edible garden with a view. At $30 to $40 per square foot, it won’t be the cheapest project, but the initial expenses are offset by lower home heating and cooling costs (up to a 20 percent savings annually).
>> Expert Tip: Your “microclimate” (sun, wind, etc.) will determine what you can grow on a roof. Brendan Shea of Recover Green Roofs suggests herbs or other low-lying greens for windy roofs, and hot peppers for roofs with maximum sun exposure.

A Windowsill
If your sill gets at least four and a half hours of daily sunlight, you have the makings of a pocket farm. Pick a south-facing window and buy a prefab window box from a hardware or gardening-supply store (be sure to anchor it properly). For best results, avoid thick terra-cotta boxes — which can get hot and “cook” plant roots with too much sun — or line them with foam, also available at hardware stores.
>> Expert Tip: “You could do salad for days out of a window box,” says Jessie Banhazl of Somerville’s Green City Growers. However, you won’t have much luck with fruiting plants like tomatoes or zucchini, which require at least a foot of soil.

A Balcony
Pretty containers are nice, but even an old recycling bin can hold a small garden (provided you’re certain the container has never contained anything toxic, and you poke drainage holes every 4 inches across the bottom). Use a mix of bagged soil and compost, and start with seeds for leafy greens and root vegetables, or sprouts for fruiting crops like cherry tomatoes or hot peppers. Water until the soil is fully soaked, every other day.
>> Expert Tip: Develop your green thumb by starting with herbs. “Buy plastic containers or terra-cotta pots and plant herbs,” Banhazl says. “Mint, chives, thyme, rosemary — those are pretty hard to kill.”

A Small Yard
Lucky you! But don’t just dig in. Boston’s industrial past means most of the soil in the city is unsuitable for farming — and it’s especially lead-filled within 3 feet of a building, says Wendy Heiger-Bernays, a professor at the BU School of Public Health. You will have to raise your crop beds: Pile at least a foot of soil mixed with compost, and find a south-facing space for maximum sunlight (you need six to eight hours a day for fruiting crops). Orient your garden so the long side goes north to south, then clear out your fridge: A 4-by-8-foot plot can yield 50 pounds of produce in a growing season.
>> Expert Tip: Maximize your productivity and dilute lead content by mixing new compost into your raised beds each spring, says Daniel Brabander, an associate professor of geosciences at Wellesley College. Also, remember to wash your hands after working with dirt that may be contaminated.

What’s in your dirt? For 10 bucks, you can send a sample to UMass Amherst, where they’ll test its pH, lead, and nutrient levels. “They tell you what you need to add to your soil to make it better,” says Courtney Hennessey of Higher Ground Farms.