Garden Climate
What is the 'USDA Hardiness Zone Map'?
What we are usually looking at with zones are the USDA Hardiness Zones. Those are broken down throughout the United States and Southern Canada. We look at the average minimum temperature, which is usually broken down in 10 degree increments.
What is the 'AHS Plant Heat Zone Map'?
The plant heat zone map was established by the American Hort Society. It tells us the number of days that an area would experience temperatures above 86 degrees. This is just as important as average low temperatures, because many plants are intolerant of high heat or particularly high humidity.
What is the 'Sunset zone map'?
That's for 13 of the western states, and it breaks those areas down into 24 different zones. It's a little more accurate, actually, than the USDA zone because it takes into account some of the other climatic factors that are involved there.
Should I rely solely on zone maps when creating my garden?
No, we really wouldn't rely just on zone maps when creating a garden because, consideration to soil moisture, particularly drainage, is critical to plant heartiness as well. Plus we are often dealing with different areas in a particular garden that might have hot sunny sides or cold wet sides. All of that will affect your plant selection, not just the zone map.
What is a 'microclimate'?
A microclimate would be a small pocket or an area within a garden that would have a slightly different temperature, or it might have a slightly different soil. But normally we look at particularly low-lying areas that would be considered frost pockets, which would be dangerous for plants. And that would be a little microclimate. Or you might have an area close to the home that's sunny, that's warm, and where you could grow plants that might not be hardy in other areas of the garden, because of that increased heat.
How can I determine the microclimates in my garden?
As gardeners, we have to be observant and pay attention to the site. Every site really has an energy, and it has different things going on in it, so we need to really be aware of what's happening in the garden. So I urge people not to rush into their garden design, but to take time to observe how the sun moves across the site, what areas might be warmer, what areas might be little frost pockets or hold cold temperatures so that you can better select lower maintenance plants.
