Garden Zones for Ohio

What garden zone am I in? This information will tell you what plants are hardy in your area and therefore can be grown with assurance that they will have the best chance of surviving and even thriving in your local environment. By starting with your garden zone and then evaluating for the micro-climates in your yard, you can identify areas where individual plants will do better… you may even find a sunny spot against a south-facing wall where you can grow a plant variety that is normally rated for a warmer zone.

The USDA published its updated plant hardiness zone map in 2012, in which they incorporates improved accuracy and detail, along with recent warming trends. Many areas were shifted an entire zone from the 1990 map, and even more from what I have come across in old gardening books from the 60’s and early 70’s.

Ohio Garden Zones and Micro-climates

USDA Plant Hardiness Zone Map of Ohio showing the 2012 zones by county.

Local and Micro-climates are important to watch, because even a small move can make a significant difference. Ohio overall is in zone 6a, with large patches of zone 5b scattered throughout the state. Most of the north coast gets a “lake effect” warming benefit that brings it up to zone 6b. This benefit extends up to around 8-10 miles south in some areas, though the local conditions are such that it is entirely possible for two adjacent neighborhoods to be in different garden zones.

By way of example, in my previous home my garden was rated solidly in zone 6b, with my garden in (naturally) the coldest and shadiest part of the yard (partly shaded by a row of arborvitaes to the south and pine and maple trees to the east and west). I also had a sunny spot close to the house and surrounded by a (heat holding) concrete driveway, which meant that I could sneak in a zone 7 plant (with fingers crossed and proper libations to all the weather gods).

My new house is about 6 miles west and is in a more wooded and wetlands filled area, as well as being further from Lake Erie (4 1/2 miles instead of 2 miles, as the crow flies). These differences put me near the border of zones 6a and 6b. I will be watching my new yard closely for micro-climate impacts from the nearby patch of woods and our 6 foot fence (shade for some areas, but white for light reflection and heat for other areas). I also will evaluate the zone based on development changes: when the 2012 zones were drawn up, this part of Avon, Ohio was minimally developed and heavily wooded. In the interim it has dramatically changed, with much new construction including shopping centers, residential developments, new roads… all of which are associated with trapping and retaining additional heat. Not enough for me to grow avocados and grapefruit in the backyard (darn!), but maybe enough, just maybe, to grow something rated for zone 7? I can dream…. (And yes, I know, All gardeners are in zone denial. Me included.).

Climate Classifications and Garden Regions

Besides the general garden zone, additional information available to define the gardening region includes the Koppen-Geiger Climate Classification, which divides climates into five main climate groups: A (tropical), B (dry), C (temperate), D (continental), and E (polar), along with the seasonal precipitation type and level of heat.

Avon, Ohio is in Koppen-Geiger Climate Zone: Dfa – Humid Continental Hot Summers.

Ecoregions and Soil Types

Much of the north coast of Ohio is in Ecoregion: 83a – Erie Lake Plain.

The Lake Erie Plain extends along the borders of Lake Erie and is a fertile crop growing region for both fruits and vegetables, as well as being renowned for it’s vineyards and wineries. It is formed from the sediment of glacial lakes, along with rocks, gravel, sand, and soil left behind by glaciers. In gardening terms that means that underneath all that nice topsoil, there’s lots of clay to deal with and also that it’s a good idea to think of uses for all the rocks you dig up!

Soils in eastern Ohio are likely to be acidic as they are derived mostly from sandstone and shale. In western Ohio the soil is less likely to be acidic due to it being formed from glacial deposits. Ohio soil in general may also have a tendency towards acidity due to the high levels of rainfall. You will still need to test your own garden soil, as your milage may vary.