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Understanding Hardiness Zones and Frost Dates

Selecting a plant for your landscape or vegetable garden can be a daunting task. Knowing and understanding your hardiness zones is a key factor in this selection.

Plants in nurseries and big box stores are bred and fed in the perfect growing conditions so that when they arrive to your local area, they are in prime condition and full bloom.

I would say that most people impulse buy when it comes to plants for their garden. All the beautiful blooms and foliage are very hard to resist.

Hardiness Zones on Plant Labels

If you want to know how to grow a particular plant in your garden, a good place to start is on the plant label. Some are more detailed than others.

Reading the plant labels though can be hard to understand if you don’t know what the numbers mean. One of the numbers on a plant tag is USDA Hardiness Zone.

It can be much easier to select a plant for your landscape by choosing one that does well in your USDA Hardiness zone.

drainage, soil ph, sunlight requirements,planting location,
hardiness zone

What Are Hardiness Zones?

First off, let me say, that with Annuals, hardiness zone doesn’t matter because they will bloom once then typically die in one season. Hardiness zones apply more to perennials and their ability to survive a certain temperature, as well as survive through or come back the next season.

The United States for instance is divided into 11 zones, starting up north and continuing down south to the tip of Florida. Each of these zones differ by about 10 to 15 degrees as their coldest temperature in Winter.

Basically, the zone the plant label displays is the temperature range the plant would typically thrive in. Anything below the displayed hardiness zoned would generally reach a temperature in Winter that would kill the plant if it’s a perennial.

There is always an exception to the rule. Some gardeners will be able to keep certain perennials alive through winter by putting them in a different location or overwintering them to help them survive through the lower temperatures.

understanding hardiness zones

Frost Dates in Your Hardiness Zone

Planting annuals and vegetables is a bit different. There are two other numbers to keep in mind when selecting these.

When planting annuals and vegetables its very important to know your Frost Dates. You can find your area’s frost date simply by Googling Frost Dates and entering your Zip code or city name to be given the information.

Frost Dates are calculated on averages of the last day a frost occurs in Spring and the first day a Frost occurs in Fall.
Every experienced gardener knows these dates can’t always be trusted, nor the temperature associated with it.

That late April freeze in southern Alabama has ruined many a crop over the years of an overzealous gardener who just couldn’t wait.

A gardener can use these temperature ranges as a guideline to know when it’s safe to plant seed or tender seedling in the ground.

Different vegetables require a certain soil temperature to germinate and longer days filled with sun to continue to grow and mature effectively.

What does “Days To Maturity” mean?

The Days to Maturity or Days to Harvest noted on a plant label, should be considered when planting vegetables.

Days to Maturity means how many days it will take the plant to become “mature” and have the ability to flower or bear fruit.

Frost dates are used to calculate a certain plant will have enough time to mature in your remaining growing season.

Do this by finding out your first frost date and counting backwards the amount of days to maturity listed on the seed packet or vegetable tag.

Keep in mind that many vegetables will have a hard time through the heat of summer so plant them early as possible. A tomato plant will grow fine in 90 degree temperatures, but it has little to no chance of setting fruit.

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