When first starting our garden, I endlessly researched what I could plant in my garden hardiness zone. I do suppose you could manage to get most any plant to come up, but I wanted to grow the plants that would thrive and produce their most because the environment suited them.
USDA Garden Hardiness zones, or “planting zones”, refer to the areas in which America, and other parts of the world are divided into for planting purposes. These zones from 1a-13b, help categorize which types of plants are most likely to thrive in your climate, taking into account winter weather, summer heat and rainfall. Knowing this information gives you specificity when researching when to plant, how much to water, when to expect harvests and what will grow most naturally in your area.
What Is My Garden Zone?
You can determine which growing zone you are in by entering your zip code in the USDA Plant Hardiness Zone Website, or looking for your city on the U.S. growing zone map.
What Does a Garden Zone Tell Me About Gardening?
- Average low temperature during winter
- When your last frost date (spring planting) and your first frost date (fall planting) are. In between these dates is your anticipated growing season length.
- Seed starting begins according to your seed packet in conjunction to your planting date, and transplanting occurs on your planting date or beyond. If I know my last frost date, I can schedule my seed starting by 12 weeks out, 10 weeks out, 8 weeks out, etc.
- As long as “days to harvest” are between your planting dates, you can begin planting that plant at anytime.
How Do I Know What Grows Well in My Zone?
All gardeners want to grow with success and abundance, not battle with plants that don’t suit their climate. With good seed companies, you are lucky enough to be able to filter through their available seeds by your zone. Each plant has a “days to maturity” label which indicates the time from seed to fruiting. In order for your seed to grow successfully in your zone, you must have enough time to grow from seed to maturity after your last frost and before your first frost.
Other factors for successful plants is knowing whether a plant prefers hot or cool weather. Flowers, like stock, prefer cool days while they mature. Vegetables like cucumbers and tomatoes prefer warm days.
Some plants require long daylight hours, like onions. They need a certain amount of daylight (for photosynthesis) to grow to maturity. Onions come in three different varieties: short day, long day and intermediate day. These differentials help you find success in your zone. This also means it is much more difficult to start an onion in the fall versus the spring because the day length is shortening. To learn more about growing onions, read more here: Growing Onions.
How Do Microclimates Affect Garden Zones?
Learning about your specific microclimate takes time spent in that space. These are the slight differences between areas in the same zone. For example, Portland, OR and Austin, TX are in the same growing zone. However, Portland is heavily affected by coastal rains in the same way that Austin can be affected by drought. Though they have the same length of growing seasons, Oregon will be able to produce a higher volume of cool weather plants during that growing season in comparison to Austin. Finding a trusted source, like a farmer or experienced gardener or local nursery, would be a good idea for learning how your zone is affected by microclimates.
How to Plant with Garden Zones:
Let’s use the example of tomatoes and Zone 8a to show how you can use garden zones to help plant your garden.
“Amish Paste” is a variety of Roma, indeterminate tomatoes. Our seed packet tells us the following information:
- Germination takes 7-14 days
- Days to maturity is 80 days
- Ideal Temperatures range from 75-95F
My zone’s last frost date is March 21st, meaning that my tomatoes could be planted without risk of frost soon after that. I also know that by end of June, our days and evenings could be in the 80’s which will slow down flower production. So earlier in the ground is better.
With this information, I’ll calculate back 90ish days from March 21st to determine when I’ll start my seeds: December 21st.
I also know that my anticipate first frost is November 15th and that temperatures will from the 100’s to the 80’s again by September or early October. So again, I can calculate back 90 days from November 15th to determine when I would start seeds: August 17th. However, I would like to harvest them for a few weeks before a risk of frost so I start my seeds for the fall on July 4th. Just an easy date to remember!
I can plan other shorter growing plants around my tomatoes, or time things to go into the ground as the tomatoes are coming out. The timing and planning produces abundance!
Zone 8a Garden Zone Tips
- Overwinter spring flowers: our spring weather warms the ground very quickly, often not giving cool weather flowers enough time to mature before heat oppression.
- Sowing carrots: plant carrots in the fall when weather begins to cool, and another round before last frost. These can overwinter in plastic hoop tunnels. You can plant a third succession in February.
- Cut flowers: while we may not be able to grow excellent dahlias, we can succeed in ranunculus! Other cut flowers include – zinnias, snapdragons, procut sunflowers, celosia, strawflower and statice.
- Plan for 2-3 seasons: the Zone 8a gardener can get away with overwintered plants for early spring harvest, an April-June harvest and a September-November harvest!
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