Urban Farming for Your Microclimate
Although you can't change your regional weather or macroclimatic conditions to be ideal for urban farming, you can figure out how to effectively analyze your own urban landscapes at a microclimatic level and make important adjustments to improve your urban gardening success. Understanding your urban microclimate can help you save money and (literally) create your own "cool place" within your urban garden space.
How to analyze your garden site
One of the first things you can do when analyzing your site is determine how much sunlight your urban garden receives. If the site is sunny, is it intense afternoon sun or gentle morning sun? If it's shady, is the shade dense enough to keep anything except woodland plants from growing, or is it dappled shade with some sunlight filtering through that will allow for a wider variety of plants?
No matter what hardiness zone you live in, keep in mind different parts of your urban garden will likely have a few climatic variations of their own. By noting these different microclimates, you can determine how to locate plants in the most suitable spots and even how to broaden the array of plants you grow.
Do a good analysis of your specific site to understand the urban challenges you need to take into consideration when it comes to plant hardiness zones because of solar glare, warmer temperatures, winds, shade, and the Heat Island Effect.
How to put the right plants in the right sites in your garden
There are basic sun versus shade considerations everyone understands. Some plants that need shade will simply burn up if you plant them in full sun. A plant that thrives on full sun will stretch and languish if you plant it in a densely shaded area.
For the urban gardener, consider all factors when matching the right plant to the right site, especially when you're working with a variety of microclimate conditions that can affect your plants growth.
For example, a portion of an urban garden sheltered from the effects of winter winds may be a half zone warmer than the rest. Often, an exposed windy spot runs cold, whereas the heat radiating from buildings and pavement in a city can up-zone an urban location.
A garden in zone 6 may successfully over-winter zone 7 plants because of microclimate variations. Conversely, you may be able to develop your zone 6 garden that shivers through temperatures worthy of zone 4! Would this be gardener's luck or the result of your careful analysis of microclimate conditions?
How to extend bloom time in your urban garden
Did you know that a large rock, a fence, a stone wall, a patio, large tree, or an adjacent building can create a unique microclimate within your urban garden? You can take advantage of these different microclimates to have a longer flowering season.
For example, if you plant daffodils on the south side of your garden, they'll likely begin peeking out of the soil earlier than those that you plant in other areas. Then when the flowers on the south side start fading, the ones that are partially shaded in another part of your garden will begin to open up. And just like that, you get a bloom time that's twice as long!
How to push the plant hardiness zone borders in your garden
You can do more than just increase bloom time when you take advantage of the different microclimates in your urban garden. You can also grow plants that are borderline hardy in your region. For example, a stone walkway or patio absorbs heat and may allow you to grow plants nearby that are usually only hardy in areas that are one zone warmer than yours.
As an added bonus, the urban environment's increased temperatures and protection from harsh winter winds may allow you even more flexibility when selecting plantings. For example, some cites in the northern U.S. have successfully planted magnolia trees in areas where the additional protection against harsh winter winds and slightly warmer temperatures can sustain these plants in urban settings.
How to overcome the impacts of wind in your urban garden
Wind also influences the microclimates in your urban garden, both by lowering air temperatures and by increasing water loss through the foliage (transpiration). For instance, winter winds can easily damage some plants, such as rhododendrons and other broad-leaved evergreens, because they don't go completely dormant. As a result, they lose some water all winter long through their leaves and cannot adequately replace that water from the frozen soil.
Strong winter winds can exacerbate this problem; therefore, protecting non-dormant plantings (like rhododendrons) from chill winds caused by an urban wind tunnel or exposed northerly exposure may be helpful to your plants' survival.