Ask anyone who lives in a big city, and they'll tell you - space is often at a premium, especially in the downtown core.
Which is why we've seen more and more rooftop gardens over the years.
It's a great, cost-effective way to grow vegetables, herbs, and other plants. Plus, it helps people eat healthier and create a sense of community.
Well, here's a really smart place to start a rooftop garden - at a hospital.
The Stony Brook University Hospital in Long Island, New York has done it, and it's worked out incredibly well.
And really, it makes perfect sense. Patients are sick. The idea is to get them better, or at least make them as comfortable. And yet, hospital food is generally lousy.
In fact, dieticians say hospital food lacks real nutritional value.
Paule Bernier of Montreal's Jewish General Hospital co-authored a study documenting how patients don't like the food and what hospitals can do to improve it.
Most hospitals devote about one per cent of their total budget to food, which breaks down to an average of $8 per patient a day.
"When someone is ill, their need for proteins and calories is much greater than when they are well, because they have wounds to heal and tissue to repair," Bernier said.
"The challenge I see is in having the proper budget to purchase quality food, a variety of food that is healing and preparing it in a way that it retains its quality."
That said, there's not any real scientific evidence to suggest that fresh vegetables help sick people recover.
But doctors at the Stony Brook University Hospital say the antioxidants can't hurt. Plus, they say fresh food has psychological benefits and sets a good example for patients for when they go home.
Dr. Josephine Connolly-Schoonen - the hospital's head of nutrition - told the New York Times "Swiss chard went over well, kale maybe not so much. When people are not feeling well, they want their comfort foods."
So, the hospital is growing all sorts of stuff - heirloom tomatoes, green peppers, lettuce, turnips, red and yellow potatoes, cilantro, basil, spinach, tender young collard greens, radishes, and broccoli with garlic to come in the spring.
The garden is 2,200 square feet. To help pay for it, the State Health Department approved a five-year grant worth $82,000, which is shared by several community gardens.
Hospital interns double as the farmers. They pick the food, bring it to the kitchen, and list everything on a board so the chefs can incorporate it in their menu.
The hospital even has room-service, if you will, so patients can order meals from a menu between 7 a.m. and 7 p.m. When they call, they can find out about any daily specials such as grilled chicken with spinach (sautéed in olive oil), along with whipped turnip (made with butter milk, salt and pepper)
Dr. Connolly-Schoonen says it's all about "creating a culture."
Canada seems to be lagging behind the U.S. on all of this but there are signs things are changing.
One example is a network called Farm to Cafeteria Canada, which is trying to get more local food into hospitals as well as into schools and universities.
In Ontario, the provincial government is making grants available so hospitals can buy local food.
St. Joseph's Health Centre in Guelph has received some of that grant money
Before 2005, nearly all the patient meals there were pre-made and outsourced. Now, the hospital prepares about 75 per cent of them from scratch.
As a result, most patients there say they're satisfied with the food, plus it's had "a huge positive impact on morale," said Leslie Carson, the manager of food and nutrition services at St. Joseph's.
Not only that, but St. Joseph's says it has cut down on the amount of food that ends up in the garbage. And it estimates that 20 per cent of its food is grown locally, contributing at least $140,000 per year to the local economy.