Plant Hardiness

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by Joe Mudd on June 21, 2012

in Gardening Tips

Here in Kentucky it’s time to get started with plans for the fall garden. This second growing season is often the best. Many of the problems we have with insect pests are reduced as the weather cools, and we sidestep the insects live cycle.

So I’ve begun planning for the fall.

Timing on fall planting depends on plant hardiness. When will frost get here? The standard way to decide is to locate your plant hardiness zone in the USDA plant hardiness zone map.

Remember ┬áthe good old days when there were maybe six or seven zones? Well times have changed. The zone map now has 13 zones. Oh, and that’s not all – each zone is subdivided as well. All this detail makes the map complex and confusing.

To help see your area more clearly, the USDA has a map for each state. Just click your state on the main map, and you’ll get a larger map of your state, showing each county. If you’re in a county which is split between two zones, like I am, you still may not be sure what exact zone you live in.

USDA zone map for KY USDA zone map for KY

There is a box at the top of the page where you can input your zip code, and you’ll get your exact hardiness zone.

All this minute details seems over the top to me. I just don’t want to think that hard about my garden. This map really isn’t much use to us gardeners. It tell you what the average low temp is for your area. That’s an interesting statistic, but not very handy for garden planning.

If you’re planning a fall garden, what you really need to know is when to expect the first frost in your area. You can then take that date, backtrack using the days to harvest number on the seed packet, and figure out when to plant the seeds.

I’ve found a few online resources to help you get your frost numbers

Victory Seeds

The folks at Victory Seeds have a page for finding frost dates. Pick your state from the list and you’ll get a list for frost dates for several cities in your state. Choose the city closest to you.

Dave’s Garden

There is a frost date finder at the Dave’s Garden website. You start by entering your zip code. You’ll get the dates for frost danger in your personal zip code area. You also get a big chart of percentages that is pretty confusing at first glance. Read the examples below the charts and things will clear up for you.

The page for frost dates gives you the first and last frost dates for the USDA hardiness zones. Their chart only lists 11 zones, and the USDA now lists 13, but you can still get a general idea for your area.

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